Distributed generation - the reality of a changing energy market

Distributed generation - the reality of a changing energy market
UPTEC F11 059
Examensarbete 30 hp
September 2011
Distributed generation - the
reality of a changing energy market
A market based evaluation and technical
description of small wind power and photovoltaics
Linda Karlsson
Abstract
Distributed generation - the reality of a changing
energy market
Linda Karlsson
Teknisk- naturvetenskaplig fakultet
UTH-enheten
Besöksadress:
Ångströmlaboratoriet
Lägerhyddsvägen 1
Hus 4, Plan 0
Postadress:
Box 536
751 21 Uppsala
Telefon:
018 – 471 30 03
Telefax:
018 – 471 30 00
Hemsida:
http://www.teknat.uu.se/student
Renewable distributed generation such as wind power and photovoltaics are gaining
popularity all over the world. The overall aim of this Master thesis was to gather
experience and knowledge regarding small wind power and photovoltaic with both a
market based evaluation and technical description. Methods used have been literature
review, interviews with market participants, evaluation of a wind mill and a
photovoltaic system simulation with PVsyst 5.41.
It was found that the main common incentive today for the development and spread
of small wind power and photovoltaics for market participants is the symbolic value. It
was also discovered that the market situation is complicated for the producing
consumer.
The spread of small wind power and PV today are a few per mille of a future
potential, where politics largely control development and spread of small-scale
solutions. The market is unclear and solutions around net charge is still an ongoing
debate. Majority of the interviewed persons believes more in PV than in small wind
power due to facts such as wind power is size-dependent and not optimal to build in
urban areas.
Results show that power quality issues are dependent on the network system as a
whole and are often a matter of cost and can be prevented with different technical
solutions. One conclusion was that bidirectional power flow increase complexity of
problems around protection. Major energy companies are involved in projects to
gather knowledge how to deal with DG both in technical aspects and how to deal
with customers practically.
Handledare: Elin Löfblad
Ämnesgranskare: Cecilia Boström
Examinator: Tomas Nyberg
ISSN: 1401-5757, UPTEC F11 059
Sponsor: Siemens AB
Acknowledgements
I would like to express my appreciation to Elin Löfblad, Head of Business Development
Siemens AB, who has been the supervisor of this thesis. Elin Löfblad has been a great
inspiration and has always had time to help and support me no matter how busy she
was. I would also like to thank the trainees at Siemens in Upplands Väsby for
introducing me to Siemens and for their great company. An extra thanks to Jakob Haller
for his support and feedback during the thesis work.
The Master thesis would not have been possible to complete without the help from a
number of persons letting me interview them and thereby letting me take part of their
knowledge and insights. Anders Björck, Carl Dohlsäter , Christer Bergerland. Daniel
Salomonsson, Inger Niss, Joakim Widén, Lennart Söder, Lina Berling, Marcus Berg, Nils
Hammar, Thorsten Handler and Ulf Östermark; thank you all so much!
There were also a number of persons at Siemens of great value to me who I could
discuss and bounce ideas with; they all gave me valuable insights of the business.
I would like to express gratitude to Jan Hintze, Joakim Hagernäs, Krister Syrtén, Martin
Hammar, Mats Rehnström and Ronny Håkansson.
Many thanks also to Cecilia Boström, researcher at the division of electricity at Uppsala
University, who has been subject reviewer on behalf of Uppsala University and helped
me complete my thesis.
Finally, I thank Rickard Östergård for his great support during the whole project, for
coming with valuable ideas and for reviewing the thesis.
Table of Contents
1
Introduction .................................................................................................................... 5
1.1
1.2
AIM OF THE THESIS .................................................................................................................................... 6
LIMITATIONS ............................................................................................................................................. 7
2
Method .......................................................................................................................... 8
3
The electricity market ..................................................................................................... 9
3.1 THE SWEDISH ELECTRICITY GRID .............................................................................................................. 9
3.2 THE FUTURE GRID – SMART GRID ............................................................................................................. 10
3.3 CONTROL INSTRUMENTS.......................................................................................................................... 12
3.3.1
Financial instruments .................................................................................................................... 12
3.3.1.1
3.3.1.2
3.3.1.3
3.3.1.4
3.3.2
Renewable electricity certificate system ................................................................................................... 12
Energy tax ................................................................................................................................................. 12
Emission rights ......................................................................................................................................... 13
Support systems ........................................................................................................................................ 13
Administrative instruments ............................................................................................................ 14
3.3.2.1 Connecting to the grid .................................................................................................................................. 14
3.3.2.1 Building permit ......................................................................................................................................... 16
3.3.3
4
Metering and settlement ................................................................................................................ 16
Distributed generation.................................................................................................. 18
4.1 SMALL-SCALE WIND POWER .................................................................................................................... 18
4.1.1
Wind power technology ................................................................................................................. 18
4.1.2
Turbine-grid connection ................................................................................................................ 20
4.2 SOLAR PHOTOVOLTAICS .......................................................................................................................... 21
4.2.1
Photovoltaic technology ................................................................................................................ 21
4.2.2
Grid-Connected Photovoltaic System............................................................................................ 22
4.3 DISTRIBUTION OF SMALL-SCALE ELECTRICITY GENERATION ................................................................... 23
4.3.1
The wind power market today ....................................................................................................... 25
4.3.2
Potential small-scale wind power market ..................................................................................... 26
4.3.3 The PV market today .......................................................................................................................... 26
4.3.3
Potential PV market ...................................................................................................................... 27
4.4 IMPACTS OF DISTRIBUTED GENERATION .................................................................................................. 28
4.4.1
Power Quality ............................................................................................................................... 28
4.4.1.1
4.4.1.2
4.4.1.3
4.4.1.4
4.4.1.5
4.4.2
5
Long-duration voltage variation ............................................................................................................... 31
Harmonics................................................................................................................................................. 32
Flicker ....................................................................................................................................................... 33
Voltage sags .............................................................................................................................................. 33
Case studies on power quality................................................................................................................... 33
Reliability and safety ..................................................................................................................... 34
Presentation of interviews ............................................................................................ 36
5.1 THE MARKET ........................................................................................................................................... 37
5.1.1
Strategies and preparations for distributed generation ................................................................ 37
5.1.2
Interest from private persons and companies................................................................................ 38
5.2 MAIN DRIVERS......................................................................................................................................... 39
5.2.1
Costumers ...................................................................................................................................... 39
5.2.2
Distributed grid operators and power trading companies ............................................................ 40
5.3 IMPACTS FROM DISTRIBUTED GENERATION ............................................................................................. 41
5.3.1
Possibilities and benefits ............................................................................................................... 41
5.3.2
Problems and obstacles ................................................................................................................. 42
5.3.3
Power quality ................................................................................................................................ 45
5.4 THE FUTURE ............................................................................................................................................ 47
5.4.1
The spread of small-scale distributed generation within 10 to 20 years ....................................... 47
5.4.2
Valuable areas for distributed generation in the future ................................................................ 49
6
Case studies ................................................................................................................ 51
6.1
6.2
EVALUATION OF WIND MILL FROM WINDEN............................................................................................ 51
PRESENTATION OF PV SYSTEM SIMULATION............................................................................................ 56
1
6.2.1
7
Choice of PV modules and inverter ............................................................................................... 57
Results ........................................................................................................................ 58
7.1
7.2
7.3
INTERVIEWS ............................................................................................................................................ 58
WINDEN EVALUATION ............................................................................................................................. 59
PV SIMULATION....................................................................................................................................... 60
8
Conclusion and discussion .......................................................................................... 64
9
Future work.................................................................................................................. 67
References .......................................................................................................................... 68
Appendix ............................................................................................................................. 76
2
Acronyms
AC
CF
DC
DER
DG
DSO
EI
IEC
PTC
PVs
REC
SCB
SvK
TSO
Alternating Current
Capacity Factor
Direct Current
Distributed Energy Recourses
Distributed Generation
Distribution System Operator
Energy Market Inspectorate (Energimarknadsinspektionen)
International Electrotechnical Commission
Power Trading Company
Photovoltaics
Renewable Electricity Certificate
Statistics Sweden (Statistiska centralbyrån)
Swedish national grid (Svenska kraftnät)
Transmission System Operator
3
List of tables
Table 3.1 Participants on the electricity market and their function ........................................ 10
Table 3.2 Prices from Fortum for grid charges. ................................................................................ 15
Table 4.1 Total installed wind power approved for the REC system 2011. .......................... 25
Table 4.2 Approved plants for REC 2011 ............................................................................................ 27
Table 4.3 Main phenomena causing electromagnetic disturbances. ........................................ 29
Table 4.4 Categories and characteristics of power system electromagnetic. ....................... 30
Table 5.1 Presentation of interviewed persons. ............................................................................... 36
Table 6.1 Specification for WindEn 45. ................................................................................................ 51
Table 6.2 Loan conditions used for the case study. ......................................................................... 54
Table 6.3 Investment calculations for WindEn 45........................................................................... 55
Table 6.4 Distribution between replaced and sold electricity for the different cases. ...... 55
Table 6.5 Technical data and information about Steca Grid 2000 inverters. ....................... 57
Table 7.1 Economic gross evaluation performed by the PVsyst V5.42. .................................. 61
Table 7.2 Investment calculations for Solarit PV system .............................................................. 62
Table 8.1 Summary of the market today and future potential. .................................................. 65
List of figures
Figure 3.1 Electricity distribution from electricity producer to electricity consumer. ....... 9
Figure 3.2 Connections between the producing consumer and market parties. ................. 15
Figure 4.1 Development of wind power turbines between 1980 and 2015. ........................ 19
Figure 4.2 Picture of a vertical axis turbine and a horizontal axis turbine. ........................... 19
Figure 4.3 Variable-speed wind turbine connected to the grid. ................................................. 20
Figure 4.4 Electrical field and movement of the charge carriers. .............................................. 21
Figure 4.5 Schematic outline of how a photovoltaic cell operates. ........................................... 22
Figure 4.6 Schematic diagram of a grid-connected system.......................................................... 23
Figure 4.7 Installed power and number of plants each year between 2004 and 2009..... 25
Figure 4.8 Cumulative installed PV power in Sweden from 1992 to 2009 ............................ 27
Figure 5.1 Measurement from PV facility in Glava 2011............................................................... 46
Figure 6.1 Power curve for WindEn 45 .............................................................................................. 52
Figure 6.2 Energy curve for WindEn 45 .............................................................................................. 52
Figure 6.3 Average wind speed above altitude of 49 m ................................................................ 53
Figure 6.4 Average wind speed above altitude of 72 m ................................................................ 53
Figure 6.5 Average wind speed above altitude of 103 m .............................................................. 53
Figure 6.6 Zoomed in area for average wind speed above altitude of 49 m.......................... 53
Figure 7.1Possibilities and benefits from distributed generation. ............................................ 58
Figure 7.2 Problems from and obstacles for distributed generation. ...................................... 58
Figure 7.3 Main incentives for the development and spread ...................................................... 59
Figure 7.4 Valuable areas for distributed generation in the future. ......................................... 59
Figure 7.5 Accumulated profit for the three cases. ......................................................................... 60
Figure 7.6 Accumulated produced electricity minus meter and service cost. ...................... 60
Figure 7.7 Normalized production (per installed kW): Nominal power 4.2 kW. ................ 61
Figure 7.8 Estimated proportions between different cost. .......................................................... 62
Figure 7.9 Result from economical evaluation of the Solarit PV system package. .............. 63
4
1
Introduction
Almost all integrated power systems in the world have been relying on centralized
electricity generation such as large-scale hydro, coal, natural gas and nuclear power
plants. Power is distributed long-distance with high voltage from centralized sources to
the customer. But the existing scenario is changing with the growth of a demand for
clean, reliable and affordable electricity generation (Lidula & Rajapakse, 2011).
Due to climate changes the use of renewable energy sources, such as wind turbines and
photovoltaic panels, have been promoted and are gaining popularity all over the world.
Many renewable energy sources are spread and the technologies are smaller scale. Elliot
(2000) point out that:
“…the current financial, organizational and institutional environment is not
very well suited to their acceptance: there is, arguably, something of a mismatch between the new technology and the existing support infrastructure.”
A major challenge for society is to obtain a sustainable energy system including
increased renewable electricity production and electrification of the transport sector.
There is a need for new technologies and solutions; a so-called smart grid, which is a
concept for future power system. The smart grid will be able to deal with new issues
that may rise with increased small-scale electricity generation such as bidirectional
power flow and security. It will allow monitoring and control of the grid in ways that is
not possible today. Smart grid is still a future concept, but many things are happening
today in the area of small-scale electricity generation.
During the last few years in Sweden the concept of small-scale electricity production has
gained massive media attention. The desire to produce their own electricity is big
amongst private persons, which is supported by a poll made by Fortum (2009). The
research shows that 9 out of 10 are positive towards producing and selling their own
electricity. Companies like Volvo are aiming for carbon dioxide neutral fabrics and IKEA
are going renewable by for example investing on solar panels to cover 150 IKEA roofs
within five years (Volvo, 2011; Stråmo, 2010; IKEA, 2011).
Companies as Bixia are marketing their power trading company as a leader of buying
local and small-scale electricity generation. Various government reports on how to make
small electricity production affordable for the consumer to become producer have been
published (Sundberg et al., 2010; Söder, 2008). The question is if the power trading
companies and distribution system operators are ready for a possible increase of smallscale electricity generation and what their incentives are for developing and spreading
the small-scale technology. Today it can actually be beneficial from an economical point
of view for owners of holiday homes, which are far from power lines, to build small-scale
generation as it costs so much to install the necessary wiring. For others customers to
become producers, so called prosumers, such a large investment cannot be motivated
economically. What are their main incentives for installing systems such as small wind
power and photovoltaics?
The local distribution system where the small-scale electricity generation takes place is
closer to consumer loads, far from large generators, and, thus increasingly affected by
changing end loads. At the same time, the local production decreases the need for the
5
long-distance power transmission (Wallerius, 2010). A difficult and interesting question
is how the distribution network is affected by an increase of distributed renewable
generation.
Photovoltaic and small wind power might increase the living standard for some of the
poorest – the ones living in the development countries, which can be hard to solve with
conventional solutions. A large part of the world’s population lacks access to electricity
because it is too expensive to provide in the traditional manner; long power lines
transmitting the small amount of electricity one can afford. Photovoltaics and smallscale wind power can for this case be a solution. But in the Western world, especially in
Sweden where we have a stable power system, is it really reasonable to build small-scale
electricity generation? What will it contribute to? And who will actually benefit from the
small-scale electricity generation except the owner? And why should it be subsided?
This thesis studies current and potential market for small-scale electricity generation in
Sweden.
1.1 Aim of the thesis
The objective of this thesis is to give a brief technical description of the small-scale
distributed generation photovoltaics and wind power and its connection to the grid. In
order to have a future perspective on the subject, the distributed generation within
smart grid is studied.
The aim of this thesis is to investigate problems and possibilities with distributed
generation according to participant on the electricity market and study political and
economic factors that influence the spread of the technology. Electric utilities and end
users of electric power are becoming increasingly concerned about the quality of electric
power, which can have a direct impact on efficiency, security and reliability (Fuchs &
Masoum, 2008). The author has therefore looked deeper into the implications on the
electricity distribution grid that can be expected with increased distributed generation
such as wind power and photovoltaic focusing on power quality.
An important objective is to look into various incentives for customers, distributed
system operators and power trading companies for the development and spread of
small electricity production. Two case studies, one with solar modules and one with a
wind mill, is done in order to evaluate economically what is required for connecting
small scale electricity to the grid and what amount of electricity the prosumer receives.
The thesis also studies the market today and aims to analyse the potential market for
small-scale wind power and photovoltaics.
The overall aim of this thesis is to gather experience and knowledge regarding smallscale generation of photovoltaic and wind power. This is significant because studies in
this area are scattered. A summary can thus contribute to a common starting point for
further development, dissemination and discussion.
6
1.2 Limitations
In the area of distributed generation, the author has chosen the technologies of small
wind power and photovoltaics because these technologies will probably dominate
during an expansion of small-scale electricity generation and therefore have the greatest
potential (Sundberg et al., 2010). Photovoltaics are treated on a consumer level and
larger scale solar power plants are therefore not included. The thesis focuses only on the
Swedish market.
The thesis does not take into account the amount of wind power and photovoltaics that
can be connected to the grid before reinforcements are necessary. The focus is to gather
knowledge and have an overview of the problems and obstacles that may occur with an
increase of grid-connected photovoltaics and small wind power. Putting a system
boundary is a complex issue that depends on several factors and this issue falls outside
the thesis work limits.
This thesis concerns the local distribution grid only, due to the fact that smaller wind
turbines and photovoltaics are often connected to the distribution system (Manwell et
al., 2009, p. 434).
7
2 Method
The thesis method can roughly by divided into three different approaches that have
been used during the project; literature review, interviews and evaluation through
simulation and analysis. Literature review was conducted first in order to gather enough
knowledge to be able to prepare interviews and simulations.
The aim of the literature review was to present distributed generation (DG), with focus
on small wind power and photovoltaics, and give basic knowledge about the
technologies and existing market situation. A literature review was also conducted in
order to gather predictions and knowledge of the potential small wind power and PV
markets in Sweden. Information regarding the Swedish electricity market and
distributed generation have been collected from:




Academic journals; received from acknowledge databases such as ScienceDirect
and EmeraldJournals.
News; articles from for example Ny Teknik.
Official homepages; such as companies’ web pages, the Swedish Central Bureau of
Statistics, the Swedish Energy Agency, Swedish national grid.
Books; for example course literature books used at Uppsala University.
All data have been reviewed and are considered reliable. A series of investigations of
small-scale power generation has during the last years been presented; including work
from Elforsk, Energy Markets Inspectorate and a Governmental Grid Connection Inquiry.
All these investigations have also been the basis of this work.
Twelve qualitative interviews were carried out in order to fulfill the aim of this thesis; to
gather in-depth knowledge and understanding of DG. Representatives from distribution
system operators, power trading companies and researches were interviewed and they
were all familiar with the topic. The interviews were semi-structured interviews, where
a primarily question designed was used to have a starting point for interviews.
Questions could then evolve and be changed during interviews depending on the
representative and what information the author was interesting in collecting. The semistructured interview gave opportunities to ask follow up questions, ask for clarifications
etc. The duration of the interviews was between 30 and 90 min, where half of the
interviews were done face-to-face and the rest were telephone interviews due to
geographical distance. Interviews was recorded by a Dictaphone and then transcribed in
order to secure reliability by not missing information while analyzing the data. Relevant
information was chosen from the interviews to fulfill the thesis objectives.
The simulation was done last in order to evaluate what amount of electricity a
household or a company could receive from investing in photovoltaic or a wind mill. The
PC software package PVsyst 5.41 was used, which is a program for the study, sizing,
simulation and data analysis of complete PV systems. Economic data was collected from
Solibro AB, a supplier of photovoltaic systems. Through contact with WindEn, a
manufacturer and turnkey provider of wind mills, both technical and economic data was
received. A deeper description of the simulation and analysis method is found under
Chapter 6.
8
3 The electricity market
3.1 The Swedish electricity grid
Today’s grid consists largely of large-scale, hierarchical and centralized electricity
generation. The Swedish electricity grid can be subdivided into three levels (SvK, 2011):
 National Transmission Grid.
The transmission grid consists of voltage levels between 220 kV and 400 kV.
 Regional Distribution Grid.
The regional distribution grid consists of voltage levels between 40 kV and 130 kV.
 Local Distribution Grid.
The local distribution grid consists of voltage levels below 40 kV.
Electricity is distributed from the energy plant through the national transmission grid,
regional distribution grid and thereafter through the local distribution grid to the
consumer, see Figure 3.1. Heavy electricity consuming industries such as melting plant
and paper industry are often delivered electricity directly from the regional distribution
grid.
Figure 3.1 Electricity distribution from electricity producer to electricity consumer.
The local distribution grid is owned by local electricity operators, the distribution
system operators (DSO). They control the operation and maintenance of the local grid.
The consumer pays for investment, operation, maintenance and for the transfer of
electricity, which is entered as a charge for electricity grid on the electric bill.
Local system operators have monopoly on the electricity grid, which partly depends on
the fact that parallel electricity supply would be economical impossible.
However, the market for power trading is open and the power trading companies (PTC)
are responsible for this. Through the electricity market place, which in the Nordic
9
regions is called Nord Pool, the power trading companies buy electricity that they sell on
to their customers. Consumers of electricity are free to choose their PTC.
Table 3.1 summarizes the different participants on the electricity market and their
function.
Electricity Producer
Grid Owner
Electricity Consumer
Owner of the facility who sells production of electricity to power trading
companies.
Manage the grid operation and is obligated to transfer electricity and is
according to law not allowed to produce or trade electricity. Grid owner is
prescribed to perform calculations and measurement of transferred
electricity. They are required to plan and expand the grid for new demands
that may rise when more renewable energy are connected to the grid. The
grid operation monopoly are divided into geographic areas where there
exists one grid owner in each area
Have an agreement with a power trading company and a distribution system
operator regarding the electricity outlet in one bleeding point.
Power trading
company
Balance Responsible
Sells electricity to consumers in competition with other power trading
companies.
The power trading company is obligated to have someone that undertakes
the responsibility for the balance in the grid. The power trading companies
can either to it themselves and make an agreement with the Swedish national
grid (SvK) or hire a company that possesses such responsibility.
Swedish national grid
Responsible to transmit electricity from the major power stations to regional
electricity networks, via the national electric grid. Swedish national grid is
responsible to ensure that there is always balance between consumption and
production in Sweden.
Table 3.1 Participants on the electricity market and their function
3.2 The future grid – smart grid
There exists no clear and standard global definition of smart grid, different persons and
organisations use various definitions (Bollen, 2010). The meaning that is incorporated
in a terminology, as in the case smart grid, is correlated with national conditions, culture
and in what stage the development is (Ståhl & Larsson, 2011, p. 22). The general
understanding is that smart grid is a concept of modernizing the electric grid; it is a
vision of the future grid.
Even if there is no standard global definition various organisations have tried to define
smart grid. International Electrotechnical Commission (IEC) describes the smart grid as:
“…an electricity network that can intelligently integrate the actions of all users
connected to it – generators, consumers and those that do both – in order to
efficiently deliver sustainable, economic and secure electricity supplies. A Smart
Grid employs innovative products and services together with intelligent
monitoring, control, communication, and self-healing technologies.”
(IEC, 2011)
10
U.S Department of Energy (2009) describes that a smart grid uses:
“…digital technology to improve reliability, security, and efficiency of the
electric system: from large generation, through the delivery systems to
electricity consumers and a growing number of distributed- generation and
storage resources.”
There are various drivers towards a smart grid capable of addressing future challenges
and opportunities. The priority of local drivers and challenges might differ from place to
place. To mention a few of them (IEC, 2011; Electricity Advisory Committee, 2008;
European Commission, 2006; SmartGrids, 2011):





Aging infrastructure, security of supply and growing demand for energy.
Integrating intermittent energy sources.
Sustainability and environmental issues such as for example an increased public
awareness of environmental issues putting pressure on politicians to reduce C02
emissions and put in place regulations to increase energy efficiency.
Liberalised market and user-centric approach.
Politics and regulatory aspects.
Utilities of smart grid need to address the variety of challenges including central power
generation in parallel to large numbers of small distributed generation, fluctuating
energy availability of renewable, increased energy trading, additional and new
consumption models (electric car, smart buildings etc.) to mention a few (Electricity
Advisory Committee, 2008). For instance, in order to control the two-way flows of
electricity when connecting small-scale decentralised production directly to the local
distribution network, the current passive network configurations will need to be
replaced by active network management. This will require, in particular, innovations in
intelligent IT-based network control (Lehtonen & Nye, 2009).
To summarize this chapter on the future grid; smart grid comprises a broad range of
technology solutions that optimize the energy value chain. Key enabler for the smart
grid is the availability of two-way data communications across the grid; something that
will allow monitoring and control of the grid in ways that is not possible today (IEEE,
2011). The design and deployment of such advanced and reliable communications
infrastructure is certainly a challenge, but it is a fundamental requirement for making
today’s grid “smarter” (IEEE, 2011). The vision is that smart grid will improve reliability,
security, and efficiency of the electric system (Electricity Advisory Committee, 2008).
The future electricity network must be (European Comission, 2006):




Flexible: fulfilling customers’ needs whilst responding to the changes and
challenges ahead;
Accessible: granting connection access to all network users, particularly for
renewable power sources and high efficiency local generation with zero or low
carbon emissions;
Reliable: assuring and improving security and quality of supply, consistent with
the demands of the digital age with resilience to hazards and uncertainties;
Economic: providing best value through innovation, efficient energy
management and ‘level playingfield’ competition and regulation.
11
3.3 Control instruments
There are various types of control for how the government can cause changes in society
and the types of control are normally divided into four main groups: administrative,
financial, informational and research-based (Energimyndigheten, 2010a).
This section deals with administrative and economic instruments that directly affect
wind power and photovoltaics. Regulations, emission limits, environmental
classification, requirements for fuel, and energy efficiency are examples of regulatory
measures. Taxes, subsidies, grants and subsidies are instead examples of economic
instruments. A final chapter includes different law change proposals on metering and
settlement for small-scale electricity generation, which is still an ongoing debate.
3.3.1 Financial instruments
3.3.1.1 Renewable electricity certificate system
In 2003, the renewable electricity certificate (REC) system was introduced in Sweden. It
is a market-based support system for increased use of renewable electricity, in which
trade takes place between producers of renewable electricity and those with quota
obligations (Energimyndigheten, 2011a). The REC system will continue until 2035
(Energimyndigheten, 2010b).
The basic principle is that producers of renewable electricity receive a certificates from
the State for each megawatt hour (MWh) generated. These certificates can then be sold
to electricity suppliers, who have a legal obligation to buy certificates relative to their
sale and use of electricity. This creates a price of certificates that lead to increased
revenues for those investing in new renewable electricity generation (Regeringskansliet,
2011a). Since its introduction in 2003, the price of the electricity certificates has been
varied between 16 and 25 öre/kWh (Energimyndigheten, 2008, p. 18).
The electricity certificate system increases the possibility for renewable energy sources
to compete with non-renewable energy sources. The plant must be approved by the
Energy Agency in order to be connected to the REC system and even the electricity
production for the own consumption is eligible for certificates.
3.3.1.2 Energy tax
Wind power and photovoltaic are not only favoured from subventions, but also from the
fact that energy sources with large carbon dioxide and sulphur emission such as coal
and oil are imposed by penalty taxes; carbon dioxide and sulphur tax.
All electricity consumed in Sweden is according to law taxable (SFS 1994:1776), but
there are some exceptions. For example for electricity produced in a wind power plant
from a producer that does not delivering electricity professional and also for a producer
with a generator output less than 100 kW who do not deliver electricity professional.
Electricity power is not taxable if it, to less than 50 kW of power, is delivered without
compensation by a producer or a supplier to a consumer that is not in privity with the
12
producer or supplier. An activity is defined professional according to law if it is part of a
business operation or if it is carried out in ways analogous to any activity pertaining to a
business with compensation from the turnover exceeding 30 000 SEK in a calendar year
(SFS 1999:1229). This should not be an issue for individuals who produce their own
electricity (Sundberg et al., 2010).
Swedish Tax Agency has judged that only the circumstances when electricity producer
feed-in electricity to the grid does not necessary mean that the producer delivers
electricity according to the way it is referred to in the legislation of energy taxation. In
addition, the Tax Agency considers letting a third part through sale or other agreement
about electricity being signed over is a prerequisite for the producer to be considered to
deliver electricity (Skatteverket, 2008). Any use of electricity for households is
otherwise subjected to 25 % VAT imposed on the electricity prices including other taxes.
For business and industry, VAT is deductible (Energimyndigheten, 2011b).
3.3.1.3 Emission rights
The aim of emission rights is to meet the requirements of reduction of greenhouse gas
emissions imposed by the Kyoto Protocol. The emission trading system let companies
trade rights to emit carbon dioxide given a limited amount of emissions rights on the
market, where one emission right grants the possessor a right to emit one tone of
carbon dioxide into the atmosphere (Utsläppsrätt.se, 2011). Corporations and
companies are assigned a certain amount of allowances by the government. If they do
not use all their allowances, these can be saved to the next period or sold to companies
that have used up their rations. Wind power and photovoltaics do not produce any
greenhouse gas emissions and therefore gain from the emissions trading system.
3.3.1.4 Support systems
The Government believes that there is an urgency to encourage the use of energy
technologies which are favorable from a climate perspective and not yet commercially
competitive with the market established techniques. For the period 2011 to 2014, the
Government proposes that the appropriation level for 1:10 Energy in the state budget to
be 122 million per year (PROP. 2010/11:1).
Previously, there was an environmental bonus (öre/kWh) for electricity from onshore
wind, a tax subsidy, but in the current situation this exists only for offshore wind power.
However, there exists a support system for wind power called wind pilot’s support
which is a support for the market introduction of large-scale wind power. The wind
pilot’s support aims to reduce the cost for the startup of wind power and to promote
new technologies (Energimyndigheten, 2010c). During the period 2008-2012, the
Government has granted the support program 350 million SEK.
Energimyndigheten has a support system for all types of grid connected photovoltaic
systems. The grant is 6o percent (55 percent for large firms) of the entire solar
installation, including both materials and labor. The photovoltaic support took effect in
2009 and extends until 31 December 2011. The maximum support amount is two
million per building and for 2011 about 50 million is granted for the support system
(Energimyndigheten, 2011c).
13
3.3.2 Administrative instruments
3.3.2.1 Connecting to the grid
For a prosumer, consumer becoming a producer, there are various market parties that
the prosumer need to contact depending if they for example want to sell surplus
electricity or not. Due to responsibility and safety reasons, connecting distributed
generation to the grid must be approved by the distribution system operator (DSO) even
if it is within the buildings own electrical wiring. The prosumer is therefore required to
contact the DSO, which are also responsible for the metering of electricity from and to
the grid (Energimyndigheten, 2011d).
All electricity producers are according to law guaranteed access to the grid (SFS
1997:857), so DSOs are bound to connect production facilities to the network provided
they meet the technical requirements for an electricity generating plant. Electricity
network companies may only refuse if there are special reasons, such as lack of capacity
in the grid. In order for the electricity producer to receive compensation for electricity
sold some administrative measures are required such as feed-in subscriptions to the
network owner together with the associated electricity metering. The electricity meter
should measure electricity in two directions, the electricity being produced and the
electricity being consumed.
For measurement and transmission of electricity to the grid, the following rules applies
among others (Sundberg et al., 2010):



Measurement in the feed-in point, where the electricity is fed into the grid, shall
refer to transmitted electricity per hour. Hourly metering is also a requirement if
the plant owner wants RECs.
The DSO company is required to install a meter with associated data collection
equipment in the electricity generators' feed-in point. The general rule is that the
electricity producer will be charged for this cost, but small production units, with
the power output of maximum 1500 kW, are excluded the cost for the meter and
its installation. These producers should only pay a reduced grid charge and only
pay for the part of the grid charge that according to grid tariff is equivalent to the
annual cost of measurement, calculation and reporting on the DSOs grid. As of
April 1, 2010 (SFS 1997:857), an amendment was introduced which means that
an user of electricity with a fuse subscription of maximum 63 A and who
produces electricity with the output power of maximum 43.5 kW, does not have
to pay network charges for the input if he or she in a calendar year not take more
electricity from the electrical system than he or she enters to the electrical
system (Energimyndigheten, 2011d).
An example of prices for grid charges is showed below in Table 3.2, where price
varies if the costumer primarily consumes or produce electricity. Table 3.2 show
Fortums prices for grid charges including production compensation and
purchase price for a small-scale electricity generation with max 63 A (Fortum,
2011).
The electricity producer is entitled compensation from the DSO where the
production unit is connected. The compensation may be formed as an loss
compensation and a power compensation for production during peak loads.
14
Prices from 2011-04-01
Consumption (withdraw
from electricity grid)
is the main subscription
Production (delivery to electricity
grid) is the main subscription
Fuse max 63 A
0 SEK*
800 SEK
(<43.5 kW)
Fuse above 63 A
380 SEK
1 840 SEK
(max 1500 kW)
*Production compensation for small-scale electricity production with max 63 A is between
3.5 – 6.1 öre/kWh depending on which grid area the producer belongs to. Purchase price of
surplus production: Nord Pools hourly spot price minus 4 öre/kWh.
Table 3.2 Prices from Fortum for grid charges including production compensation and purchase
price for small electricity production with max 63 A.
Contact with a power trading company (PTC) is necessary if the prosumer wishes to sell
the surplus electricity. PTCs have different policies regarding buying electricity from
small-scale producers. If the prosumer also wants RECs, then contact with the Swedish
energy agency and the transmission system operator (TSO) Swedish national grid (SvK)
is needed. RECs are applied for at the Swedish Energy Agency and managed by SvK. The
production can be measured at the grid connection point or at the production unit to
obtain RECs, where the last option requires an extra electricity meter. The additional
cost for the extra meter makes the option with measurement at the production unit
unprofitable for small-scale producers and is therefore commonly not an option. The
connections between the prosumer and market parties are clarified in Figure 3.2. A
prosumer may also have to contact the Counties Agency in order to take part of the
subsidiary system for PV systems and apply for building permit at the County Building
Committee depending on design of the wind power system.
Power Trading
Company (PTC)
• Buys electricity
• Trading fee
• REC compensation
Distribution
System Operator
(DSO)
Municipality
• Subsidiaries
• Building permit
Producing
costumer
Swedish Energy
Agency
• Application for
approval of REC
• Small compensation
• Grid fee
Transmission
System Operator
(TSO)
• REC
• Transfer fee for REC
Figure 3.2 Connections between the producing consumer and market parties.
15
3.3.2.1 Building permit
In order to place wind power a building permit might be required depending on the
properties of the wind power station. The owner of the wind power stations needs
building permit if:



wind power turbine diameter is more than two meters;
wind power station is mounted in top of a building;
wind power is placed closer to the boundary of the building plot then the actual
height of the wind power tower.
(Energimyndigheten, 2008)
Building permit is applied for at the County Building Committee which evaluates the
application and the sites adequacy. There are for example restrictions such as shore
protection and valuable nature area protection. The laws required appear in the plan
and construction law. An environmental registration according to the Environmental
Code is required if the wind power turbines power is above 125 kW.
3.3.3 Metering and settlement
There have during the last years been two greater investigations dealing with issues
around metering and settlement for small-scale electricity generation, one government
Grid Connection Inquiry investigation with Lennart Söder, professor from KTH, in
charge and another one conducted by the Energy Market Inspectorate (Söder. 2008;
Sundberg et al., 2010).
During 2008 the results from the government Grid Connection Inquiry investigation was
presented, which dealt with connection of renewable electricity production and
proposed some amendments for small-scale electricity producers. The Inquiry’s
proposals were for example (Söder, 2008):


Small power plants of less than 63 A (which is equivalent to an output of around
44kW) can be connected without requiring hourly metering and the possibility
for small producers to net meter and net debit, which would lead to significantly
simplification and lower costs.
The 1 500 kW limit for reduced network charges should be replaces by a ceiling
on the network charge of 0.03 SEK/kWh.
During the fall of 2010 the Energy Market Inspectorate (EI) presented proposals on the
issue of net charge for small electricity producing plants, where net charge is a set-off
between electricity being feed-in and electricity being ejected for a fixed period. Net
charge can be done in two ways, either by the set-off taking place in the meter (net
metering) or by continuing to measure and report feed-in and ejected electricity
separately and instead letting the set-off take place through the billing (net debiting).
The first way, set-off taking place in the meter, is not reasonable according to EI because
of issues such as impaired balance settlement and it is not compatible with current tax
legislation. They made the judgment that the input and withdrawal of electricity should
continue to be measured separately and that the input should continue to be measured
16
hourly and also be deducted hourly. However, they had some suggestions for changes
regarding the offset between electricity being feed-in and ejected from the national grid:


Impose an obligation for DSOs to in the billing monthly set-off electricity being
feed-in with ejected electricity from the grid. This means that DSOs should base
the variable component of grid tariffs on the net between feed-in and ejected
electricity during one month. Possible fixed charges in the grid tariff are not
affected by the set-off. The set-off apply as long as the feed-in does not exceed the
ejection of electricity per month. DSOs are therefore not obligated to pay for the
surplus electricity that electricity consumer may have per month. The obligated
set-off only apply for customers with own generation with a fuse rating of up to
63 A. The customer should during the year also be a net consumer of electricity.
Introduce no obligation for power trading companies to in the billing set-off the
feed-in of electricity with ejection of electricity. Instead, it is up to the electricity
user with their own electricity generation to make an agreement about set-off or
sale of surplus electricity.
Energy Market Inspectorate presents in their report that their proposals would mean a
slightly improved economy for electricity consumers with their own electricity
generation. Proposed rule changes will not in any significant way change the conditions
for electricity consumers who have invested or want to invest in their own generation.
However, the inspectorate additionally proposes two possible ways how to improve the
profitability for small producers of electricity in its report. Their proposals are about
offsetting the energy tax and do adjustments to the REC system.
The Swedish Tax Agency has in a submission of comment to the Energy Market
Inspectorate report opposed themselves the task of investigating the possibilities to
change tax rules so that net charge can be allowed to include the energy taxation and
VAT in desired manner. This is according to the Swedish Tax Agency not compatible
with existing EU directives (Skatteverket, 2011).
Elforsk states in their report Konsekvenser av avräkningsperiodens längd vid
nettodebitering av solel that the way PV systems electricity contribution are handled
today give in general very small PV systems in comparison to what could have been
possible and appropriate. The problem exists due to the fact that the PV system owner
receives a zero or low value for the surplus electricity in relation to the electricity
purchased from the grid. Without net billing it is economically optimal to install only up
to about 2-7 m2 of the approximately 60 m2 that are available on the roof of a singlefamily house. Elforsk states that:
“For the further development of the PV market in Sweden it is of utmost
importance to make it possible, as soon as possible, for PV system owners to get
a reasonable compensation for their excess electricity. Net billing would be an
easy way to solve this problem. The most practical and easiest way to achieve
net billing would be if the grid owner could send a net value to the electricity
trader.”
(Molin et al., 2010)
17
There exists various discussions about net billing and the topic has received much media
attentions during the last year. The governmental inquiry 2008 advised net billing, the
government and the Ministry of Economy are working on the subject, but nothing has
happened despite the fact that three years has passed (Söderberg et al., 2011). The
latest news is that the government plans a new investigation how the system of net
debiting could be designed (Olofsson, 2011).
4 Distributed generation
Small-scale generation is also generally called distributed generation (DG), embedded
generation and decentralised generation. There exists no consensus regarding a
concrete definition of distributed generation in the literature (Pepermans et al., 2005).
Different criteria’s concerning for example voltage level at grid connection, generation
capacity (MW) and generation technology are used. In the article Distributed generation:
definition, benefits and issues (Pepermans et al., 2005) the authors favour the definition
of distributed generation as:
“…an electrical power generation source connected directly to the distribution
network or on the customer side of the meter.”
This view is rather broad and for the research question of this thesis it is necessary to
further narrow this definition, therefore the definition in the book Electrical Power
system quality (Dugan et al., 2003, p. 31) will be used:
“…generation dispersed throughout the power system as opposed to large,
central station power plants. DG typically refers to units less than 1500 kW in
size that are interconnected with the distribution system rather than the
transmission system.”
The limit of 1500 kW also comport with the definition of small-scale generation
according to the electricity legislation (SFS 1997:857). The small-scale generation,
primarily for household requirements, usually deals with smaller power output. DG can
both include renewable and non-renewable technologies (Glover et al., 2010, p. 34), and
this thesis is primarily concerned with the renewable technologies wind power and
photovoltaics. In the following subchapters, the technologies wind power and
photovoltaics are described together with information of today’s and potential market.
4.1 Small-scale wind power
4.1.1 Wind power technology
The use of wind energy as a resource of generating electricity is one of the fastest
growing renewable energy technologies worldwide (Boyle, 2004). The wind accelerates
the turbine blades coupled to a generator, which generate electricity. The two most
common types of generators used in wind power are induction and synchronous
generators. Majority of wind turbine drive trains have a gearbox coupled between
generator and turbine, to transform the slower rotational speed of the turbine to higher
18
rotational speed on the generator side. However, with the development of power
electronics, configurations without a gearbox have become more common. Commercial
wind power has through the years become more advanced, bigger and with higher
power output, see Figure 4.1. Maximal turbine size is redoubled approximately each fifth
year and today’s commercial turbines has the output power of about 5 MW and a rotor
diameter up to 120 m. The turbine sizes are expected to increase to about 10 MW with a
rotor diameter of 180 m during the years 2010-2015 (Ekström, 2009).
Figure 4.1 Development of wind power turbines between 1980 and 2015 (Ekström, 2009).
Small-scale wind generation is not near as cost-effective as large scale units. Even so,
during the last years the demand for small-scale wind power has grown, but the market
contains quality problems according to critics who are critical against suppliers (Hållén,
2009; Feuk, 2009; De Decker, 2009). Modern wind turbines come in two basic
configurations: horizontal axis and vertical axis, the former being the more common one,
see Figure 4.2. The wind turbine operating configuration can also be classified into two
categories, fixed-speed turbine and variable-speed turbine.
Figure 4.2 Picture of a vertical axis turbine to the left (Floating Windfarms Cooperation, 2011) and
on the right a horizontal axis turbine (Siemens, 2011).
The power produced by a wind turbine is naturally affected and varies with wind speed.
Every turbine has a characteristic wind speed-power curve that together with the wind
speed frequency distribution on the site can tell how much power the wind turbine
approximately will produce. Wind force between 4 and 25 m/s is normally the working
area of wind power. The terrain features on wind characteristics is of great importance
and can be of such great energy output that the economics of a project depends on
finding the proper site.
19
4.1.2 Turbine-grid connection
Different designs of wind-turbines are available on the market as mentioned in Chapter
4.1.1. For most small wind power turbines, permanent magnet synchronous generators
are the generator of choice today because of their higher efficiency and they do not
require any external excitation current. Direct-drive technology for wind power is
increasing because the gearbox (GB) can be eliminated (Baroudi et al., 2007; Carrasco et
al., 2006; Manwell et al., 2009).
For a variable-speed wind turbine with a synchronous generator (SG) the power
produced in the power output from the generator is initially variable voltage and
frequency AC. The output must first be rectified to DC and then converted back to AC
with fixed frequency and voltage for connection to the grid. The rectified DC power can
also be directed to DC load or battery storage. Figure 4.3 shows the scheme of a variablespeed wind turbine with a synchronous generator connected to the grid.
GB
SG
~
=
=
Transformer
~
Grid
~
Voltage source
converters
Figure 4.3 Variable-speed wind turbine with a synchronous generator connected to the grid.
The turbine-grid connection consists, in addition to the electrical equipment associated
with the wind turbine mentioned above in Figure 4.3, with the following equipment
(Manwell et al., 2009):





Switchgear: is used to connect and disconnect power plants from the grid and
should be designed for fast automatic operation in case of a grid failure or
turbine problem.
Protection equipment: to secure that turbine problems are not harmfully
affecting the grid and the other way around. If there is an over-voltage situation
in the wind power system, a short circuit or deviations from the grid frequency
due to grid failure, the equipment should disconnect the wind power system from
the grid. Sensors in the protection equipment should detect various problem
conditions.
Electrical conductors: (cables) to connect the wind power system to the grid.
Transformers: Converting the generated power to voltage of the local electrical
grid to which the turbine is connected. It may also be used to obtain voltages of
appropriate level for various ancillary pieces of equipment at the site. Wind
turbines over approximately 100 kW produce electricity with 690 V, therefore a
transformer is placed near the wind tower (Alvarez, 2006).
Grounding: to protect equipment from lightning damage and short circuit
ground.
20
4.2 Solar Photovoltaics
4.2.1 Photovoltaic technology
A photovoltaic (PV) cell consists, essentially, of two layers of semiconducting materials,
an n-type semiconductor and a p-type semiconductor. These semiconductors can be
made of different materials and are usually divided into different groups depending on
material. The most common semiconductor material used is silicon, therefore the
electrical characteristics of a photovoltaic cell is described considering silicon-based
semiconductor. The n-type material consists of a surplus of free electrons because the
material has been doped with donor impurities. The p-type material has been doped
with different donor impurities which causes a deficit of free electrons. These ‘absent’
electrons are called holes, which can be considered equivalent to positively charged
particles.
Silicon contains four valance electrons. The n-type region can, for example, be doped
with phosphorus containing five valance electrons and the p-type regions with boron
containing three. By adding these two different semiconductors together we create a p-n
junction where some of the electrons from the n-regions will diffuse to the p-regions
creating a positive charge in the n-region, and some of the holes will diffuse from the pregion, creating a negative charge in the p-region, see Figure 4.4. This sets up an electric
field in regions of the junction, which is depletion region.
Figure 4.4 Electrical field and movement of the charge carriers (Eicker, 2003, p 209).
When photons from the sunlight fall on the photovoltaic cell (p-n junction), energy from
photons can be transmitted to electrons or if the photons contain enough energy it can
excite electrons to a higher conduction band. The amount of energy needed to excite
electrons to a higher conduction band depends on the band gap of the semiconducting
material. In this excited state an electron leaves a hole in the valance band. Two charge
carriers, an electron-hole pair, are thus generated. Due to the electric field around the
junction, electrons will tend to move into the n-region and the holes into the p-region.
The flow of electrons, by definition a current, can be used by adding contacts to each
side of the photovoltaic cell to get DC. Figure 4.5 shows schematically the operation of a
photovoltaic cell. A single PV cell typically produces voltage of about 0.5 V (SolElprogrammet, 2011). Photovoltaic cells are, in order to deal with higher voltages and to
provide protection and isolation, assembled into modules. The modules generally
contain 36 photovoltaic cells and are the building blocks of larger photovoltaic arrays.
21
The reliability of a silicon-based PV system is high, maintenance need is low and lifespan
is more than 25 years (Ekström, 2009).
Electron flow
n-type
surplus of electrones
Metal conducts
+
-
External load
Electron
V
Hole
p-type
shortage of electrones
Figure 4.5 Schematic outline of how a photovoltaic cell operates. The cell contains n- and p-type
regions with different charges. This makes excited electrons and ‘left-over’ holes move in different
directions and if the two sides of the cells are connected through a load, an electric current will
flow as long as sunlight strikes the cell.
4.2.2 Grid-Connected Photovoltaic System
The voltage at which the maximum power can be extracted changes with sunlight
intensity and cell temperature. Since electrical power is most commonly used in AC form
some form of power conversion is required between the PV modules and the electrical
load.
The cables of the PV modules connected in series are combined into parallel strings in a
PV junction box containing over-voltage protection and possibly string diodes. The
following components are used to connect the PV junction box to the grid (Deutsche
Gesellschaft für Sonnenenergie, 2008):





Grid-connected inverter
Cabling, wiring and connection system
DC load switch
AC switch disconnector
Electricity meter
22
The PV junction box is connected to a grid-connected inverter through a DC load switch.
The switch makes it possible to switch off the voltage from PV modules, enabling
maintenance work at the inverter (SolEl-programmet, 2011).
The grid-connected inverter transforms the DC electricity generated by the PV arrays
into AC electricity at a voltage and frequency that can be accepted by the grid.
With a coupling to the building’s grid, the solar power is first consumed within the
building and any surplus is fed into the local grid. Standalone systems also have
inverters, but should not be confused with the grid-converted inverter with different
features. Voltage levels of the grid are controlled by the inverter to secure that no
dangerous voltages are fed in to the grid. In the event of grid power failure, the inverter
shuts down automatically as a safety measure (Energimyndigheten 2011c). The inverter
also adjusts its operating point to the maximum power of the modules, which varies due
to weather conditions, in order to function optimally (Deutsche Gesellschaft für
Sonnenenergie, 2008).
The inverter is connected to the building’s distribution board through an AC switch
disconnector and an electricity meter. The disconnecting switch enables the inverters to
separate from the grid voltage and the meter is installed to give full control over the
production (SolEl-programmet, 2011). Figure 4.5 shows a schematic diagram of a gridconnected system.
AC loads
PV array
Inverter/power
conditioner
Distribution panel
Electric utility grid
Figure 4.6 Schematic diagram of a grid-connected system, where the electricity from the PV system
can either be used immediately or be feed-in to the electric utility grid. When the solar system is
unable to provide the electricity required, power can be bought from the network.
4.3 Distribution of small-scale electricity generation
Distributed generation has so far in Sweden been used in limited extent, but there exist a
decreasing demand according to resellers (Palm & Tengvard, 2009) in combination with
enhanced political management control measures that during the last years advocate
renewable electricity production (PROP. 2009/10:133; Energimyndigheten, 2010b).
Within distributed generation, PVs and wind power are during the next couples of years
estimated the fastest growth in Sweden (Sundberg et al., 2010).
Globally there is a strong political support for renewable energy sources. Governments
strive to be more environmental friendly in their way of acting and struggle to reduce
23
carbon and greenhouse emissions. According to many experts, the electricity price is
expected to increase in the future, which can have a positive impact on the development
and expansion of small-scale renewable electricity generation in general.
At Swedenergy (Svensk Energi) they believe that the next great switch can be the own
production of electricity (Holmkvist, 2009). Neither the own production of electricity
from photovoltaic or small-scale wind power are competitive against buying electricity
from the Swedish grid. With mass production and getting the manufacturing prices
down there exists a possibility for them to be a competitive choice in the future
(Ekström, 2009). Potential and opportunities also depends on the government and its
policies. Politicians control economical rules, taxes, permits and other bureaucratic
processes (Vinnova, 2009).
The desire to produce its own electricity is big amongst private persons, which have got
support from a poll made by Fortum (2009). The research shows that 9 out of 10 are
positive towards producing and selling their own electricity. In addition, the research
reveals that 7 out of 10 think that it should be standard with solar panels or wind power
as well a charging pole outside the house when you build a block of apartments. There is
much that indicates that photovoltaics will be the technique first of choice due to its
simplicity and because it does not impact the surroundings the same way as wind power
(Holmkvist, 2009).
In order to give a view of the photovoltaic and wind power markets, the following
chapters will go through the markets today and future potential.
Potential market regarding small-scale wind power and PV systems can be evaluated
according to different considerations; natural, technical and economic potential. Often
the different considerations are interlaced. The natural potential deals with natural
conditions as for example total land area to build wind power. The technical potential
deals with today’s technology and the possible technical development of the future.
Technical potential often include the use of capacity factor (CF). The capacity factor of
any plant is the ratio of the actual energy produced, for the time considered, to the
energy that could have been generated at continuous full-power operation during the
same period, i.e. the hypothetical maximum possible output. Annual capacity factor is
often used to evaluate the productivity of different plants. Finally economic potential
incorporate evaluation of what is economical feasible or desirable to realize.
24
4.3.1 The wind power market today
Wind power development has during the last couple of years been immense, see Figure
4.7. A development that most likely will continue due to climate and planning goals set
by the government that Sweden should have 30 TWh wind power by 2020
(Regeringskansliet, 2011b). Net electricity production 2009 was 2,49 TWh
(Energimyndigheten, 2010c), where net electricity production is the gross production of
electricity minus the internal use of electricity in the power plants.
400
Number and MW
350
300
250
Installed power (MW)
200
Number of plants
150
100
50
0
2004
2005
2006
2007
2008
2009
Year
Figure 4.7 Installed power and number of plants each year between 2004 and 2009
(Energimyndigheten, 2010c).
Sweden has around 2 MW installed power from sold wind turbines below the nominal
power output of 44 kW (Sundberg et al., 2010; Svensk Vindkraftförening, 2009). It is not
feasible for all small-scale wind power to be connected to the REC system, which can be
noticed by data from approved plants for REC system 2011. Table 4.1 indicates the total
installed power for various nominal power output sizes (Energimyndigheten, 2011e).
Total normal
production per year*
[MWh]
Total installed
power
[kW]
Installed power ≤ 44 kW
951
637
Installed power ≤ 50 kW
1 471
872
Installed power ≤ 1500 kW
1 145 879
535 035
*The total normal production per year is the number specified in the application from the plant
owner
Table 4.1 Total installed power for approved wind power plants for the REC system 2011 below
the nominal power output of 1500 kW.
25
4.3.2 Potential small-scale wind power market
The plan for Sweden is to have 30 TWh by 2020, where the government mainly has large
wind power in mind. Sweden has large land area for wind power, but wind
circumstances and nearest distance to existing residences have a limiting factor for
small-scale wind power (Energimyndigheten, 2005).
The total potential for small-scale wind power is about 11 TWh according to a report
from the Energy Markets Inspectorate (Sundberg et al., 2010) which interlace natural
and technical potential with today’s technology. The potential have been based on three
typical plants and four types of customer segments according to the following:




Villas (1.7 million) are assumed to install a 2.2 kW plant per villa, which requires
no buildings permit.
Holiday houses (0.6 million grid connected) are assumed to install a 5 kW turbine
per house.
Apartment blocks (2.5 million apartments), which are assumed to have an
average of four floors and with the potential to install a smaller wind turbine (2.2
kW) per apartment on the upper floor. The assumptions gives the potential of 0.6
million turbines.
Farmers (73 000 farmer companies) are expected to install a 20 kW wind mill.
Wind mill is according Swedish definition wind power with total height between
20 and 50 meters.
(Sundberg et al., 2010)
It is important to be aware that this is an estimated maximum potential today and that
there are various obstacles, this potential will therefore not be realized in any close
future. It is in good wind situations, bringing a higher capacity factor (CF), that the
economical calculation will be somewhat attractive for the consumer. The average
European CF is less than 21 % according to studies investigating average realized CFs
between 2003 and 2007 for various European countries (Boccard, 2010). Realized CFs
oscillates over time and regions and are in the 20-30% range. Ackermann (2005) show
similar values that CF often lies in the range of 25 % (low wind speed location) to 40 %
(high wind speed locations). Another obstacle for reaching the maximum potential is the
building permit required to build wind power in densely build areas. It should also be
pointed out that there were about 71 100 farmer companies 2010 in Sweden with
minimum five hectare agriculture land (Jordbruksverket, 2011), which means that
these farmers probably could install a wind mill larger than 20kW.
4.3.3 The PV market today
Total accumulative installed power in PV systems in Sweden was during 2009 8.8 MW,
where 3.6 MW was grid-connected PV systems. The rise of installed PV between 1992
and 2009 can be seen in Figure 4.8, where the increase of grid-connected PV during
2006 is explained by the supporting system from the government that started the same
year (Hultqvist, 2010).
26
Off-grid nondomestic
Gridconnected distributed
Gridconnected centralized
Off-grid domestic
19
92
19
94
19
96
19
98
20
00
20
02
20
04
20
06
20
08
kW
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Year
Figure 4.8 Cumulative installed PV power in Sweden from 1992 to 2009 divided into different offgrid and grid-connected markets.
In the REC system 2008 Sweden had five approved PV systems and 2011 the number is
16 approved PV systems with total installed power of 580 kW (Energimyndigheten,
2011e). Table 4.2 shows the statistics over plants approved for the certificate system for
2011.
Nr of plants
Nr of small-scale
Nr of micro-scale
in REC system
≤1,5 MW
≤ 50 kW
Wind power
1405
834
33
Hydropower
1194
1087
247
Bioelectricity
178
98
33
PV
16
16
14
Sum
2793
2035
327
Table 4.2 Approved plants for REC 2011 (Energimyndigheten, 2011e).
4.3.3 Potential PV market
The technical potential can for example be calculated from total roof and front surface
area on buildings available in Sweden with orientation and construction under
consideration (Energimyndigheten, 2005). The capacity factor when it comes to PV
depends on how many hours the sun shine during the year, which depends on for
example geographical location. Factors such as shading, temperature, gradient and
orientation also have an impact on the CP. Widén (2010) has calculated the potential
amount of building-mounted PV in Sweden together with measurement of solar
irradiation between 1992 and 1999 from the Swedish Meterological and Hydrological
Institute (SMHI). According to Widén (2010) a total building surface of 709 km2 was
available, but after reduction of unfavourable oriented surfaces a total area of 370 km2
was used in his calculations. The result was that PV generation could have been on
average 37 TWh per year between 1992 and 1999 (Widén, 2010, pp. 85-86) and gives
apprehension of the PV potential in Sweden.
27
The price to produce electricity from the sun has gradually declined and photovoltaic
can today be a profitable alternative in special application where there is a lack of
electricity grid. However, the prices are still too high to create a commercial selfsupporting market for grid-connected PV systems. It will take a high cost reduction, an
increased electricity price and alternative rules regarding net charge for economic
arguments to drive expansion (Sundberg et al., 2010). Improved technology also makes
the production more efficient and the investment cheaper. The Swedish Energy Agency
estimates that a commercial breakthrough can happen around year 2025
(Energimyndigheten, 2003,).
4.4 Impacts of distributed generation
Various impacts of distributed generation are brought up by literature and there is an ongoing debate about the subject, where benefits such as diversity among energy resources
and increased renewable energy sources witch contribute to reduction of CO2 emissions are
mentioned. Other benefits mentioned are that production is closer to the customer with the
possibility to reduce losses in the distribution grid and voltage drop to customers.
Distributed generation is connected directly to existing electric power delivery system
at the distribution level and thereby relieving some of the necessity to invest in
transmission system expansion (Pecas Lopes et al., 2007)
At the same time it is important to consider additional costs as well as benefits of
distributed generation such as cost for possible redesign of the protection system
(Ackerman et al., 2001). The integration of variable generation presents challenges such
as voltage fluctuation, power system transient and harmonics, reactive power, storage
systems, load management, forecast and scheduling. The following chapter focus mainly
on distributed generation impact on power quality. Reliability and safety issues are
mentioned briefly.
4.4.1 Power Quality
Both electric utilities and end users of electric power are becoming increasingly
concerned about the quality of electric power. Power quality is an important aspect of
power systems with direct impacts on efficiency, security and reliability and is therefore
important to address when looking at distributed production of electricity (Fuchs et al.,
2008). A reason for increased concerns regarding the quality of electric power is the
continued push for increasing productivity for all utility customers. When entire
processes become automated, the efficient operation of machines and their controls
becomes increasingly dependent on quality power (Dugan et al., 2003).
There are number of important power quality issues that must be addressed as part of
the overall interconnection evaluation for distributed generation (Dugan et al., 2003).
Depending on the aspect chosen, distributed generation can either contribute to or
deteriorate power quality.
Before going further in depth with power quality, an explanation of the concept power
quality will be given. Power quality refers to a wide variety of electromagnetic
phenomena that characterize the voltage and current at a given time and location on the
power system (IEEE Std. 1159, 2009). There exists no strict definition of power quality
28
and it can depend on one’s frame of reference. There are standard for voltage and other
technical criteria that may be measured, such as the European Standard EN 50160 on
voltage characteristics of electricity supplied by public distribution systems (IEEE Std.
1159, 2009). EN 50160 gives for example limits for voltage magnitude variations.
However, long-term effects are in these standards somewhat forgotten and some
countries use requirements that are stricter than descriptions in EN 50160 (Bollen &
Verde, 2008). At the end power quality is a consumer-driven issue and the end user’s
point of reference is prioritised such as stated in the book Electrical Power Systems
Quality (Dugan et al., 2003):
“Power quality is any power problem manifested in voltage, current, or
frequency deviations that result in failure or misoperation of customer
equipment.”
However, it is important to remember that voltage characteristics are under influence of
several parties such as end users, equipment and system manufacturers, designers of
plants and installations, electricity distributors, public authorities and general public. It
therefore falls upon the responsibility of all these parties to maintain a good electrical
environment (IEEE Std. 1159, 2009). Furthermore, depending on the grid and turbines,
introduction of wind turbines may help to support and stabilize a local grid (Manwell et
al., 2009). At times, the introduction may also lead to problems that limit the magnitude
of the wind power that can be connected to the grid (Manwell et al., 2009). Table 4.3
show main phenomena causing electromagnetic disturbances according to IEC
classifications (IEEE Std. 1159, 2009), which can be further described by listing
appropriate attributes depending if they are steady-state phenomena or a non-steadystate phenomena.
Conducted low-frequency phenomena
Harmonics, interharmonics
Signalling voltage
Voltage fluctuations
Voltage dips
Voltage imbalance
Power frequency variations
Induced low-frequency voltages
DC components in AC networks
Radiated low-frequency phenomena
Magnetic fields
Electric fields
Conducted high-frequency phenomena
Induced continuous wave (CW) voltages or currents
Unidirectional transients
Oscillatory transients
Radiated high-frequency phenomena
Magnetic fields
Electric fields
Electromagnetic field
Steady-state waves
Transients
Electrostatic discharge phenomena (ESD)
Nuclear electromagnetic pulse (NEMP)
Table 4.3 Main phenomena causing electromagnetic disturbances.
29
Amplitude, frequency, spectrum, modulation, source impedance, notch depth and notch
area are attributes that can be used to describe steady-state phenomena further. For
non-steady state phenomena, other attributes may be required such as rate of rise,
amplitude, duration, spectrum, frequency, rate of occurrence, energy potential and
source impedance (IEEE Std. 1156, 2009; Dugan et al., 2003). Table 4.4 shows the
categorization of electromagnetic phenomena used for the power quality community
more in detail; it provides information regarding typical spectral content, duration and
magnitude where appropriate for each category of power system electromagnetic.
1.0
1.1
1.1.1
1.1.2
1.1.3
1.2
1.2.1
1.2.2
1.2.3
2.0
2.1
2.1.1
2.1.2
2.1.3
2.2
2.2.1
2.2.2
2.2.3
2.3
2.3.1
2.3.2
2.3.3
3.0
3.1
3.2
3.3
4.0
5.0
5.1
5.2
5.3
5.4
5.5
6.0
Categories
Transients
Impulsive
Nanosecond
Microsecond
Millisecond
Oscillatory
Low frequency
Medium frequency
High frequency
Short-duration variations
Instantaneous
Interruption
Sag (dip)
Swell
Momentary
Interruption
Sag (dip)
Swell
Temporary
Interruption
Sag (dip)
Swell
Long-duration variations
Interruptions, sustained
Undervoltages
Overvoltages
Voltage unbalance
Waveform distortion
DC offset
Harmonics
Interharmonics
Notching
Noise
Voltage fluctuations
Typical spectral
content
Typical
duration
Typical voltage
magnitude
5-ns rise
1-µs rise
0.1-ms rise
<50 ns
50 ns-1 ms
>1 ms
<5 kHz
5-500 kHz
0.5 - 5 MHz
0.3-50 ms
20 µs
5 µs
0-4 pu
0-8pu
0-4 pu
0.5-30 cycles
0.5-30 cycles
0.5-30 cycles
<0.1 pu
0.1-0.9 pu
1.1-1.8 pu
30 cycles-3 s
30 cycles-3 s
30 cycles-3 s
<0.1 pu
0.1-0.9 pu
1.1-1.4 pu
3 s-1 min
3 s-1 min
3 s-1 min
<0.1 pu
0.1-0.9 pu
1.1-1.2 pu
>1 min
>1 min
>1 min
Steady state
0.0 pu
0.8-0.9 pu
1.1-1.2 pu
0.5-2%
Steady state
Steady state
Steady state
Steady state
Steady state
Intermittent
0-0.1 %
0-20 %
0-2 %
0-100th harmonic
0-6 kHz
Broadband
<25 Hz
0-1 %
0.1-7 %
0.2-2 Pst
7.0
Power frequency
<10 s
variations
NOTE: s=second, ns=nanosecond, µs=microsecond, ms =millisecond, kHz = kilohertz,
MHz=megahertz, min=minute, pu=per unit
Table 4.4 Categories and characteristics of power system electromagnetic.
30
Power quality is a complex issue, and this thesis aim is to focus on the power quality
issues regarding the connection of distributed renewable generation to the grid.
Therefore, all the different phenomena listed in Table 4.4 will not be described. Focus
are on power quality problems mainly mentioned and discussed in literature (Khadem
et al., 2010; Latheef et al., 2008; Papathanassiou, 2007).
The power quality issues covered by this report are:




Long-duration voltage variation
Harmonics
Flicker
Voltage sags (dips)
The nature of these power quality issues is related among others to the ‘short-circuit
capacity’, a measure of the internal impedance in the network, which depends on the
network’s internal configuration (Pepermans et al., 2005), which includes nominal
power of the generator. The wind power generator type has a great influence on the
power quality (Hægermark, 1997).
Studies from Gotland Energi and Chalmers show that it is not only the “short-circuit
capacity” that influences the voltage variations; it is also consumers reactive
consumption and the X/R ratio of the distribution system (Hægermark, 1997). The X is
the collection system reactance and R is the collection system resistance. The weaker the
grid is the greater are the voltage fluctuations. Some power quality phenomena are very
noticeable when they take place in weak systems and pass practically unnoticed when
they happen in strong distribution networks (Gomez Targarona & Morcos, 2007, p 296).
A great issue when considering wind power is that wind generators overwhelming
feature induction-asynchronous generators. While these machines are particularly well
suited to the variable speed nature of wind machines, they cannot operate without
reactive power support from the network to which they are connected. There exists a
need for reactive power support when penetration of wind power increases (Glover et
al., 2010, p. 39).
4.4.1.1 Long-duration voltage variation
Overvoltages and undervoltages are generally not the result of system faults, but are
caused by load variations on the system and system switching operations (Dugan et al.,
2003, p. 18). The power variation from renewable sources such as wind and solar can
cause these voltage fluctuations and the reactive needs of the wind turbine. For windturbines, the interaction with the grid depends on the turbine under consideration, and
on the electrical grid to which the turbines are connected.
“For example wind turbines, especially inductive machines, tend to absorb
reactive power from the system and produce a low power factor. If turbines
absorb too much reactive power, the system can become unstable.”
(Manwell et al, 2009, p 437)
31
In order to maintain the electric system stability a literature survey (de Alegria et al.,
2007) suggest that new wind farms, i.e. larger wind power plants, must be able to
provide voltage and reactive power control, frequency control and fault ride-through
capability.
Overvoltages are usually the result of load switching (switching off a large load or
energizing a capacitor bank). The overvoltages results because either the system is too
weak for the desired voltage regulations or voltage controls are inadequate.
Undervoltages are usually a result of the reverse scenario than overvoltages, a load
switching on or a capacitor bank switching off (Dugan et al., 2003, p. 19).
Small distributed generation is not powerful enough to regulate the voltage and will be
dominated by the daily voltage changes in the utility system. Small DG is almost
universally required to interconnect with a fixed power factor or fixed reactive power
control (Dugan et al., 2003, p. 390). Large voltage changes are possible if there is a
significant penetration of dispersed, smaller DG producing a constant power factor.
Suddenly connecting or disconnecting such generation can result in a relatively large
voltage change that will persist until recognized by the voltage-regulating system.
Voltage levels are sometimes described as a limiting factor for distributed generation
(Carlstedt et al., 2006), but voltage management is rather a design problem and a matter
of economy according to Widén (2010).
4.4.1.2 Harmonics
Harmonics are sinusoidal voltages or currents having a frequency that are multiples of
the grid frequency, the frequency at which the supply system is designed to operate.
Harmonics produce waveform distortion together with the fundamental voltage or
current.
Power electronic equipment is a major contributor of harmonics to the power system,
such as for example drivers, rectifiers, inverters and switched-mode power supplies.
As stated by IEEE (IEEE Std. 1159, 2009):
“These devices and load can usually be modelled as current sources that inject
harmonic currents into the power system. Voltage distortion results as these
currents cause nonlinear voltage drops across the system impedance.”
The applications of power electronic equipment is increasing, which makes harmonics
distortion a growing concern for many customers and the power system taken as a
whole (IEEE Std. 1159, 2009). Requirements for harmonics can be found in the
standards EN 50160 and EN 61000.
Damaging effects of harmonics, if not properly contained and filtered, are for instance
incorrect operation of control devices, additional losses in capacitors and transformers,
causing parallel and series resonance frequencies, resulting in voltage amplification
even at a remote location form the distorting load (Fuchs & Masoum, 2008).
32
According to Manwell et al. (2009), the power electronic in variable-speed wind
turbines connected to the distribution grid introduce harmonics into the distribution
system. A number of distributed generation technologies rely on some form of power
electronic device in conjunction with the distributed network interface, such as for
example the dc-to-ac converter for photovoltaic systems. All of these devices inject
currents that are not perfect sinusoidal (Glover et al., 2010, pp. 39-40).
4.4.1.3 Flicker
Flicker is commonly due to rapid changes in the load or to switching operations in the
system. The term flicker is derived from the impact of the voltage fluctuation that causes
lights to shift brightness perceived by the human eye. The shift of light intensity is
measured with respect to the sensitivity of the human eye (IEEE Std. 1159, 2009).
Introducing wind turbines into a distribution grid, these disturbances (Manwell et al.,
2009) can occur from the connection and disconnection of turbines, changing of
generators on two-generator turbines, and by torque fluctuations in fixed-speed
turbines as a result of turbulence, tower shadow, wind shear, and pitch changes. Flicker
does not harm equipment, but in weak grids with higher possibility of voltage
fluctuations, the perceived flicker can be very disturbing to customers. I many countries
it therefore exits standards including limits for unacceptable flicker and step change in
voltage (Manwell et al., 2009, p. 438).
4.4.1.4 Voltage sags
A voltage sag is a case of short-duration voltage variations and is a decrease to between
0.1 and 0.9 pu in rms voltage or current at the power frequency for durations from 0.5
cycle to 1 min. Voltage sags are usually associated with system faults, but can also be
caused by energization of heavy loads or starting of large motors. Wind turbines can
themselves be the reason for voltage sags within the network (Latheef et al., 2008).
Short fluctuations of irradiance, shading effects and cloud cover can cause voltage
fluctuations in a low-voltage distribution grid with high penetration of PV (Khadem et
al., 2010). Attention should therefore be paid to the voltage profile and the power flow
of the line. Elforsk (Åkerlund et al., 2006) propose a hypothesis in their rapport Skadade
apparater that sags are very dangerous to electronic equipment due to inrush current
which arises when sage cease and line voltage returns.
Depending on the generation technology, loading conditions and the interconnection
location, DG might have the ability help reduce voltage drops at high-load situation.
However, at low-load situation a massive excess of DG production, upper voltage limits
could be violated (Widén, 2010).
4.4.1.5 Case studies on power quality
Power quality measurements performed on a low-voltage grid, in Hjärtholmen near
Gothenburg, with two 225 kW pitch-controlled wind turbines put on-line (with
induction generators) shows that fundamental voltage level is lowered as much as 3 %.
Also, as the wind turbines are put on-line a fast decaying transient occurs. During the
wind turbine operation, the harmonic content is increased on the local wind park grid,
33
where the phase-compensating capacitors are the cause for the increase. The research
also shows that the risk for flicker increase with lower X/R ratio and with use of
turbines which have tendency to produce large periodic fluctuations (Thiringer, 1996).
Widén (2010) modelled and simulated three existing Swedish low voltage (LV) grids to
study the power system impact. He concludes in his PhD thesis:
“…power flow studies showed that voltage rise in LV grids is not a limiting
factor for integration of PV-DG. Profound impacts on the power system were
found only for the most extreme scenarios.”
(Widén, 2010)
In general, the low voltage grid seems to cope with a high penetration level of
photovoltaic, the limitations are not technical or the access of solar energy, but rather
the difficulties for the captive producer to utilize the excess production of electricity. Not
being able to utilize the production of electricity heavily limits the sizes of the installed
systems and the pay-back time increase (Widén, 2010).
Widén’s conclusions are also in line with a European funded project in Germany, where
several case studies were investigated regarding impact of PV generation on power PQ
in urban areas with high PV population. Results from the German study show that:
“Distributed generation from PV system with high ratio of generation capacity
to transformer ratio, i.e. a ratio of 80 % and higher, in general does not
deteriorate the quality of the grid. PQ was found to be affected only with regard
to increased voltage levels at the end of LV feeders. Generally, all power quality
requirements as described by the European standard EN 50160 were satisfied.”
(Cobben et al., 2008)
A list of EN 50160 requirements for low voltage grids can be found in Appendix A.
4.4.2 Reliability and safety
There exists more network considerations than power quality to be addressed with
distributed generation in focus, example of key issues are (Glover et al., 2010, p. 40):
Reliability: Intermittent power production such as solar and wind power depends on
Mother Nature. The need of electricity does not always coincide with the production and
there is a need for reserve margin. Since more generation are connected to the
distribution system, a single outage could curtail the whole accessibility of generation
facilities.
Safety: It is important that individual feeders are disconnected under maintenance of
the grid. An unwanted ‘islanding” operation, where part of the grid is energized, is very
dangerous for the personnel working on the line but also the loads connected to them
(Niss, 2011). Sophisticated protective relaying schemes must be designed and
implemented properly when distributed generation is connected on the same
distribution feeder.
34
In addition:
“Bi-directional power flows make it difficult to tune the protection systems in
the grid: short-circuits and overloads are supplied by multiple sources, each
independently not detecting the abnormal. “
(Pepermans et al., 2005)
As mentioned by Bertling (2011), smart grid is a way of solving this problem by
including protection system in order to cup with the increase distributed generation.
Also active management of distribution network can enable significant increase of the
amount of DG that can be connected to the existing grid (Pecas Lopes et al., 2007).
35
5 Presentation of interviews
In this section results from interviews are presented and also the literature review
conducted about main drivers for consumers. The presentation is grouped in a similar
way as the questions were asked, under certain topics, in order to simplify the overview
of various opinions and facts for a specific topic. Interview was conducted with four
researchers, one representative from Elforsk, two employees at smaller DSOs, one
employee for a trading company and representatives from three large energy companies
in Sweden. These to give a broad view over opinion and knowledge of the situation of
distributed generation today and thoughts about the future. The most important things
from every interview have been selected with respect to the aim of this thesis. In Table
5.1 follows a short presentation of interviewed persons.
Lina Bertling
Professor in Sustainable Electric Power System and Head of the Division
of Electric Power Engineering at Chalmers University of Technology.
Lennart Söder
Professor at the division of electric power systems at KTH Royal
Institute of Technology.
Joakim Widén
Researcher at the department of Engineering Sciences at Uppsala
University and author of the dissertation System studies and simulations
of distributed photovoltaics in Sweden.
Marcus Berg
Lecturer for the division of electricity at Uppsala University.
Coordinator for Wind Power – Technology and Systems course given at
Uppsala University.
Anders Björck
Project manager for Elforsks’ research program Vindforsk.
Christer Bergerland
Manager for research and development Sweden, Fortum.
Ulf Östermark
Project Manager Smart Grid Innovation, Göteborg Energi.
Nils Hammar
Service Developer and project leader for micro production project,
Göteborg Energi.
Inger Niss
Chief of electrical distribution, Utsikt.
Thorsten Handler
Engineer at Bergs Tingslags Elektriska (Btea). He has been involved with
the group Elinorr.
Carl Dohlsäter
Energy trader, Bixia Energy Management.
Daniel Salomonsson
Senior research and development engineer, Vattenfall R&D, Power
Technology.
Table 5.1 Presentation of interviewed persons.
36
5.1 The market
5.1.1 Strategies and preparations for distributed generation
Göteborg Energi has put focus on research and development on smart grid and also on
microproduction such as photovoltaics (Ulf Östermark, 2011). Nils Hammar (2011) is
project leader for a micro production project at Göteborg Energi mentions different sub
targets with the project:



It is very hard for the ordinary consumer wanting to be a producer. It is hard to
know what it cost, what are the rules and so on. We have tried to straighten it out
by making our information outwards better, for example on our homepage.
We have developed concrete services so people can turn to us and ask for
photovoltaic panels without having to be good on the technology. The thought is
to offer total solutions; the service behind including for example management of
different contracts with for example power trading companies and request for
economical support, installation and mounting.
Göteborg Energi is involved in a project at Göteborgs University, “Potential
photovoltaic energy production on roof structures”.
In addition, Göteborg Energi Din El has introduced a net charge, or more correctly a full
price compensation, for the first 100 costumers connecting small-scale electricity
production with the maximum rated power of 6 kW.
Fortum (Christer Bergerland, 2011) are involved in the smart grid project in Norra
Djurgårdsstaden, where they want to gain knowledge how the integration of various
sources can cooperate in a smarter way. There are also various discussions about for
example tariff systems, problems and opportunities for the future electricity market.
The challenge is that we do not know; there is no key. Bergerland mentions that they
have to learn from the process and try different tariff systems and market models.
Fortums ambition is to make it simple to the costumers.
Vattenfalls ambition is to develop a clear strategy regarding small-scale distributed
generation to show their support and to have something they can communication with
the costumers (Daniel Salomonsson, 2011). Integration of distributed generation may
cause problems that we are not aware of today and these puts some fear in the
distribution system operators, says Salomonsson. Vattenfall have recently started a
project where they will try to identify these problems and hopefully solve them. The
work will be done by first putting up different scenarios for what will happen until 2020
and 2030. From that a document will be worked out how Vattenfall will work with these
issues in order to deal with them in the best way. This will be broken down further to
see how the distribution system operator will handle it; for Vattenfall this means how
the distribution grid technically will deal with these changing conditions in the best way.
37
At Bixia they have strong profiling towards DG, they do not only want to follow the
development; they want be part of it according to Carl Dohlsäter (2011). He adds:
“We offer private persons and companies to buy the surplus electricity and we
give relatively good compensation. Bixia also have photovoltaics packets for
sale, where we offer 3-4 different packages with relative small size. Our
photovoltaic partner is a company in Kristinehamn, so the customers can easy
buy their PV system and get going fast.”
The distribution system operator (DSO) company Utsikt supports two local projects
regarding small-scale electricity production; one villa in Lindköping with photovoltaic
panels and a summer house with combined photovoltaic and wind power production in
Katrineholm. In the projects Utsikt tries out a form of net charge. The goal is to offer net
charge to every costumer if both projects work out well (Inger Niss, 2011). The projects
do not follow the formal set of rules, but they have not received any feedback from the
Energy Markets Inspectorate. However, Energy Markets Inspectorate has made a
proposal for the government regarding rules about small-scale electricity production
which Utsikt are not satisfied with. Today we do not know if our rules are going to be
accepted or not in the future, says Niss (2011).
The DSO company Btea are part of the Elinorr group which consists of fifteen DSO
companies from the southern parts of the region Norrland of Sweden, where the group
has recommended their members to do a real set-off between consumption and
production. Btea are doing this type of set-off which builds on having two meter
indication, one for the electricity delivered to the house and one for electricity leaving
the house. Thorsten Handler (2011) describes their set-off and talks about solutions for
when the meter from the house goes faster than the one to the house. He also mentions
how they solved the situation with the Swedish Tax Agency. We do not view this smallscale electricity generation as production; it is energy efficiency say Handler.
5.1.2 Interest from private persons and companies
The interest has increased quite heavily the last period, especially on the solar side,
according to the respondent from Bixia. He believes the reason is the subvention for
installing grid-connected photovoltaic systems. From private persons there is a massive
interest for photovoltaic systems, but there is not the same interest for small wind
power. It is not as simple, even if you put up a small, it cause noise and there are higher
requirements for the installation. It does not have the production as one expects,
according to Dolhsäter (2011). Also Göteborg Energi has seen a great interest for smallscale electricity generation. There are companies wanting to have a green profile by
having photovoltaics on the roof or a small wind wheel and quite many private persons
being enthusiast and believing in this (Hammar, 2011).
Ustikt on the other hand has not seen a big interest of costumers wanting to connect
themselves to the grid, there are some that asks about it. However, Niss (2011) adds that
the municipality in Lindköping has invested quite a lot in solar energy, but they have not
produced surplus electricity so net charge is not an issue. Vattenfall has neither seen a
big interest in Sweden, but there has been in Germany (Salomonsson, 2011).
38
5.2 Main drivers
Solar energy and wind power market is driven by same trends as all renewable type of
energy. Main drivers are the increased need for power, especially in development
countries, the threat against our world’s climate and the price in general. Fossil fuels
have for example had increase in price during the last period and the price for different
technologies within renewable energy is important (Vinnova, 2011). This chapter will
conclude the research done regarding different incentives for individual participants on
the energy market. Participants treated are prosumers, distribution system operator
and power trading company.
5.2.1 Costumers
Various studies on consumer attitudes towards domestic PV systems and small-scale
wind power have been conducted (Faiers & Neame, 2006; Palm & Tengvard, 2009;
Kaplan, 1999). Kaplan (1999) identifies various incentives for the adoption of
Photovoltaic; knowledge, motivation, technical understanding, experience and use of
new technology. A motivation factor is, for example, independency, where the producer
is independent of an energy company, and the symbolic value of showing your product
to others. People want to show that they care about the environment.
Palm & Tengvard (2009) carried out in-depth interviews with members of 20
households regarding their main motives for adopting PVs or micro wind power
generation. The researchers connect their research to previous studies that use Rogers
Diffusion of innovations. The theory explains the mechanics of the diffusion process,
how a product or idea is accepted by the market. According to Rogers (2003) there exist
five categories of product adopters: (1) Innovators (2) Early adaptors (3) Early majority
(4) Late majority and (5) Laggards. Appling Rogers Diffusion of innovations, households
using microgeneration are innovators or early adaptors on this market, where
innovators are seen as venturesome. Innovators and early adaptors generally have the
characteristics of higher education and social status than the majority of the population.
Late majority are more skeptical towards innovations and prefer traditional solutions
(Rogers, 2003).
Main findings from the research of Palm & Tengvard (2009) about the main motives for
adopting PV or micro wind power generation are:



Environmental concern; represents a way to take action in the energy area.
Symbolic value; offering the household a way to visualize environmental
awareness (to neighbors and friends) or setting an example to others.
Protest against the major energy companies and to be able to become
independent. There was also a wish to become less vulnerable to power failure.
The households not adopting the techniques did it primarily for three reasons:



Economic reasons.
Could not find a suitable place to install the product.
They did not want to intrude (their neighbors) and destroy the neighborhood.
39
5.2.2 Distributed grid operators and power trading companies
In order to have the outside perspective of which incentives there can be for distribution
system operator and power trading company various researcher where asked the
question which incentives there exists for this type of companies for the develop and
spread of small-scale distributed generation technology.
Lennart Söder (2011) said that there exists no direct economic interest for the
distribution system operators (DSO). It is rather about keeping a good relationship with
customers because the DSO is tied together with the power trading company. If
customers like their DSO the possibility exists that they also buy their electricity from
the trading company within the same corporation. Joakim Widén (2011) could not see
any direct incentives for the DSO, but mentioned that it is about profile the company as
‘green’. Today, it already exist power trading companies with the business idea to buy
small-scale distributed generation. For example, they can buy electricity from
photovoltaic generation and sell it much more expensive to people who wants to buy
photovoltaic electricity. The small-scale production is also an extra production for the
power trading companies in case something happens. It can then be a finesse to have
extra capacity installed in case it is needed according to Lina Bertling (2011). Both
Bertling and Marcus Berg (2011) cannot see any direct driving forces for the DSO. It is
rather a problem today with few profits and it is easier to stay away from it (Bertling
2011). Due to rational reasons it is not worth the hassle to be involved with small-scale
production (Berg, 2011). Anders Björck (2011) is involved a great deal with both power
trading companies and distributed system operators in his work. He tells that both
power trading companies and DSO are positive to small-scale distributed generation
such as for example small-scale wind power.
“If customers think it is good, then it is good.”
(Björck, 2011)
The outside perspective has now been summarized and same question was also asked to
the distribution system operators and power trading companies; what incentives there
are for them for the developed and spread of small-scale distributed generation
technology. Bergerland (2011) from Fortum, mentioned that incentives for DSO are
decrease in losses and a decreased exchange with the superincumbent grids. There is no
business for a power trading companies to buy electricity from small producers due to
the fact that the handling costs are much higher than an actual gain. Instead of business
it is rather about policy and image. It is not a business opportunity if you do not think
that you can tie up electricity trade agreements.
Göteborg Energi is a municipality own energy company with the defined mission to
work for a sustainable Gothenburg. They do not have a short-term profit objective as
maybe a pure private energy company. The company can according to Hammar (2011)
be more long-term and see further with commonweal. Additionally, in the long run, it
can be profitable to work with distributed generation if subventions changes or if
Sweden get feed-in-tariffs.
40
“The market might then explode and then we have to know this and be in the
front. Today we know much about large scale plants such as biogas and
thermal power station, but there is not much knowledge regarding the smallscale such as wind and sun power and this is an area we need to learn more
about.”
(Hammar, 2011)
Niss (2011) cannot state that there is a big advantage with local small-scale distribution,
but is decrease to some extent losses in their grid and it may avoid lean-tos in the pace
that they do today. She also highlights the World conscience as incentive to get rid of as
much carbon dioxide discharge as possible.
Handler (2011) from Btea, believes that there could be a great deal of stand-alone
systems in the future due to the rapid technical development. If the DSO are not
attractive enough or easy to cooperate with, people might get frustrated because they
cannot separate who is behaving bad on the energy market and out of protest make
themselves independent and disconnect from the grid. From society’s perspective, a
large grid is better to have as a big battery connected to other countries.
At the power trading company Bixia they work for the most part with small-scale
distribution that is a little bit bigger, most of them are normal size wind power plant
owners and also some larger hydro power plants owners. The incentive is therefore to
buy electricity from detached participants. Buying from small-scale distribution also
goes in line with their policies and standards, they want to support multiplicity and they
believe that the optimal is if everyone could produce their own electricity and have the
opportunity to influence on their own way. As stated in the VINNOVA rapport; on a
deregulated market the Swedish power trading companies might have an interest to
offer solar power to their customers who wants to influence their energy mix and also to
offer financing solutions, expert help and service. Through offering the customers
several services, the PTC could be an interesting choice for customers (Vinnova, 2011).
5.3 Impacts from distributed generation
5.3.1 Possibilities and benefits
A benefit according to Niss (2011) is that small-scale distribution connected directly to
existing electric power delivery system leads to reduce losses, insofar that it actually
lowers the consumption in the grid and relieves some of the necessity to invest in
transmission system expansion. Relieved system expansion is also a benefit mentioned
by Pecas Lopes et al. (2007). Hammar (2011) and majority of the researchers also
mentions the reduce losses, but even if this is important Hammar (2011) adds that this
is not the main benefit and reason for using distributed generation. Even if you calculate
the losses, building an enormous power plant in North of Sweden will still be more
profitable. Another question is who will benefit from the reduced losses (Widén, 2011).
The reduced losses are in the subordinated grids, but for the local distribution system
operator there might be no difference (Salomonsson, 2011). One way of looking at
distributed generation is as a mean to integrate as much renewable production in the
energy system (Hammar, 2011). This aspect is also mentioned by Niss (2011); it is a way
to reduce the CO2 emissions.
41
Large power plants take a long time to get on the spot; it can take years until all the
permits are proved. Photovoltaic have the advantage that it can go quite fast and
become a potential tool (Hammar, 2011). A benefit that Björck (2011) can see is if you
have a smaller area, then you could put up a smaller wind power plant.
Various persons mentioned that distributed generation, such as small-scale wind power
and photovoltaic, increase the awareness and commitment where the energy comes
from and the consumption (Hammar, Handler, Dohlsäter; 2011). Studies have been
conducted on this subject and they show that the consumption of energy decreases from
the impact of distributed generation (Dobbyn & Thomas, 2005; Sauter & Watson, 2007).
Dohlsäter (2011) highlights the benefit that energy consumers can control their own
energy production and liberate themselves from the big players.
Östermark (2011) at Göteborg Energi believes that the small-scale electricity production
is an important snowplough to start discussions and look at changes regarding what is
allowed to do. It is an alarm clock for government and companies working with the
electricity grid and energy; it is a mental warm-up. Today the electricity law is very thin
and need to be changed according to Handler (2011).
5.3.2 Problems and obstacles
A difficulty today is that the grid on lower voltage, the local grid, is not built to receive
new generation and here you have the smart grid ideas coming in. It is about gain of
capacity, new security system, the communication between different technical solutions
and products (Bertling, 2011). Bergerland (2011) also mentions the increased
complexity of problem around fuses, protective relays and other types of protection
when flow of electricity goes two ways. It can be hard to detect problem if you have local
production, according to Salomonsson (2011). The grid is not built to handle two-way
flows and the protections are not built to deal with this. The control and protection
systems have to be adaptive so you know in witch operating situation you are in and this
is something missing today. Salomonssos (2011) discuss the safety issue further:
“If you have a short circuit in the network then you have quite a high shortcircuit power, so it becomes easy to detect and break away. If your own solar
panel get an error, then it is not certain that it provides enough for you to
detect that and there is a safety issue. So protection is not only about
equipment, you must also have sufficient short circuit power so you can detect
and break out the errors.”
The question is then who should pay for the new products. The costs are big for
connecting the small-scale distributed generation to the grid, and Bertlings’ (2011)
belief is that one should not connect themselves do the grid if it is not needed. In the
interview with Hammar (2011) he states that there have been thoughts if there could be
any problem for the local grid with distributed generation, but he has a hard time
thinking there would be.
42
Bergerland (2011) brings up smart grid and much of it deals with the presumption of a
very large increase of renewable energy not being steerable into the grid, such as wind
power and photovoltaic. If you cannot control large variation of power up and down
during different hours locally, then the balance of the grid must be controlled from
somewhere else. The operating reserve has a cost and smart grid deals with this. The
regulation power cost will increase in the future and maybe it is not possible to only
invest in production facilities using all wind power and photovoltaic, but rather invest in
the load more and try to control it to follow the production. Not letting the load become
static and just being there.
The development of wind power has been from small-scale to large scale. The big
difference is how much electricity you can get for the money, but mainly that it blows
much more on 100 meters height then on the roof spot where you put the small-scale
wind power wheel. It is the height that is of main important for the small-scale wind
power rather than the technical development itself (Björck, 2011). The height is also
something that Dolhsäter talks about; the really small plants with height of 15-30 meter
are not enough. They most up at least 70-80 meters, but then the cost for the pole is so
expensive that it is not realizable. Small-scale wind power will be hard in urban areas, to
not say impossible, due to neighbors according to Handler. Hammar also mentions the
esthetical part, that many thinks it is a quite ugly and not so architectural appealing.
Unfortunately, many people think that wind power is good, but not on their backyard
says Dohlsäter.
The economic issues, legal issues, political issues and the mismatch between production
and consumption are discussed as problem and hindrance by the majority of the
interviewed persons.
When it comes to small-scale plants such as PV you have to be a little enthusiast and not
only look at the investment cost, but consider it in another way (Dolhsäter, 2011).
The biggest problem today is that small-scale distribution, such as PV, is not economical
appealing today if you calculate with today electricity price, but this can change with
subventions and so on (Hammar, 2011). It is also very hard to know how it works if you
want to be connected and deliver surplus electricity to the grid; how the DSO and the
trading companies are connected, who the prosumer should report to etc. (Hammar,
2011). Dohlsäter mention that there is a much unclarity about the offset between
production and consumption and how it should be dealt with.
There is a mismatch between on-site demand and supply for household with PV
systems. Widén has addressed questions around this mismatch in his dissertation thesis,
which he also talks about during the interview.
“As long as a surplus electricity is submitted for free to the grid or receives a
very low credit, which currently is the case in Sweden, it is reasonable to adjust
the system size so that there is no or low risk for overproduction.”
(Widén, 2010, p 71)
43
Net metering reduces the mismatch and has a considerable impact on the production
value and on the system size that is reasonable to install, but as Widén & Svensson
(2010) found:
“Net metering reduces the mismatch by subcontracting net production from
net demand over a billing period and saves substantial amounts of purchased
electricity compared to the business-as-usual situation. In effect, the system
sizes that are reasonable to install are more than doubled with monthly net
metering and several larger with annual net metering. Without net metering,
the systems sizes that would be installed to maximize the production would
only cover a minor fraction of the annual demands.”
Discussions have been going on for years regarding for example net charging, but
nothing is happening and that is not good for anyone. Söders proposal was good, but
then it got totally diluted and EI gave an entirely different proposal says Bergerland
(2011). Begerland discuss some differences between the two proposals:
“Söders’ proposal suggest that the costumer could pair the production with
consumption, and it would then be monthly or on an annual basis. This would
mean that you would not have to pay taxes and moms. The proposal from
Energy Market Inspectorate on the other hand imply that you would have to
pay energy tax and moms on all consumption and that you should pair part of
production with the electricity grid and not the electricity market. Costumers
would not get the possible gain and it would be complicated for us and
everybody else involved. We run this question through Svensk Energi, but the
Swedish Tax Agency does not want to deal with it.”
The Swedish Tax Agency has officially gone out with a statement of opinio that they do
not want to deal with the question (Skatteverket, 2011).
Hammar (2011) from Göteborg Energi mentioned that he was part of the investigation
from Energy Market Inspectorate.
“We were clear that we wanted offset straight off, that the distribution system
operators should be able to handle the whole question without involving the
power trading company monthly. We suggested, as many others, a situation
where the DSO monthly net charge before they send the measured value to the
power trading companies. Energy Market Inspectorate suggested something
different, that one should only net charge the electricity grid.”
At Bixia they would like to see, for photovoltaic, some kind of paring of production and
consumption; paring of the surplus during summer with the shortage during winter.
From everyone’s point of view some form of yearly or monthly pairing would be simple
belief Dohlsäter (2011).
Söder (2011) put focus on two main problems for small-scale distributed generation;
annual production versus annual consumption and the metering issue. If you produce
more then you consume during a year, you automatically become an electricity
producer. There are three types of metering depending on the time interval; annually,
44
monthly and hourly. He does not think that annual metering is compatible with today’s
deregulated market. Net charge functions together with today’s monthly net metering
according to Söder. He has a hard time seeing it function together with hourly metering.
With the metering comes the issues around DSO and taxes, the DSO will get less if I start
to produce my own electricity and the Swedish tax agency will also get less. If you have
net charging, it may be viewed as a subvention, where goes the limit? Who should be
allowed to net charge? The electricity certificate is another thing that is not beneficial
towards small-scale producers. The issue about REC is also mentioned by Bergerland
(2011) who mention that the REC system is not suited for small-scale electricity
production. They are not taking part of the subventions existing today and that is an
obstacle according to Bergerland.
All of the interviewed mentions the political aspect as a big hindrance towards smallscale electricity generation. Most part of technology exits, it is rather about putting
everything together and a question of costs (Bertling, 2011). A problem though is energy
storage (Bertling, Berg, Widén; 2011). The batteries are in the present situation really
expensive.
5.3.3 Power quality
The electric power system is a complex system, but it is actually much about the ability
for the system to transfer electricity with as few losses as possible and to secure the
power quality that we want. There are various ideas regarding power quality, some
saying there is no problem due to the variety of new machines and systems no longer as
sensitive to power quality. It is very hard to answer questions about power quality
because it depends on the system you have whether it is sensitive or not, says Bertling
(2011).
“I believe it is important to always have the cost aspect in mind. You should not
have better power quality than you need; otherwise it is a waste of resources.”
(Bertling, 2011)
Berg (2011) talks about different power quality problems that can occur with wind
power such as flicker, harmonics and reactive power but also points out that it is a
complex issue. It depends on the grid, specific technology used for production and load
profile. Östermark (2011) mentions that power quality is a challenge but more a
question of cost which goes inline what Söder says:
“There are some challenges regarding power quality, but it is not a problem.
We have engineers and power electronics; we can dimension better grids and so
on. The trouble is when other devices build on the fact that there is no power
quality problem, but here you can think around and change the settings for the
device. The question still remains who is the responsible? Is it the producer
causing changes on frequency or the device owner?”
(Söder, 2011)
At Fortum they anticipate that problems with power quality are a risk factor
(Bergerland, 2011). However, there are no clear evidence or rapports that there are any
problems. Bergerland himself has performed measurements on a photovoltaic facility;
45
Glava in Värmland. He has established that the power output fluctuations are quite
variable, during a minute you can have the power going two or three times from 10 % of
the maximum power to 100 %. Figure 5.1 shows Bergerlands measurements during a
day in March. It depends how strong the grid is if it becomes a large problem, but it is
definitely a problem transferred to the grid. As mentioned before, Fortum see this as a
risk factor, but it does not exceed the standard limits of today. Transformers today are
not build to deal with this fast voltage fluctuations, it is not an automatic control system
built to deal with this type of problems. So Bergerland comment that there are some
technical aspects that they are learning too.
Figure 5.1 Measurement from one of the photovoltaic facilities in Glava during March 12, 2011.
As mentioned before, Vattenfall is starting up a project to identify possible problems.
They have investigated the technology, but the investigation of impact on the grid has
just started (Salomonsson, 2011). So far, they are aware that local variations can cause
problems, but they have until now not seen any problems in Germany. Today they do
not see any problems regarding the grid in Sweden; it is rather a question how to deal
with small-scale electricity production practically.
Hammar (2011) is not worried about power quality today, he refers to Germany who
last year installed 250 000 PV systems in one year and we have about 100 gridconnected PV systems in our grid he says. In Germany they have managed themselves
quite good, and there is a long way before we have to worry about getting grid problems
from small-scale distributed generation. Niss (2011) highlights that power quality is
something that Utsikt needs to pay attention to because they are responsible for the
electricity grid, but they have not seen any problems so far. She does not believe that
small wind power or photovoltaic impact the grid more than farmers using their
machines, but with increased distributed generation this is something they will have to
follow up.
46
Handler (2011) recognizes that they do not have much knowledge about small-scale
distributed generation and that is the reason why they are starting to look at the area
now. At Btea they only have two samples of what can happen with power quality.
“One occurred at my installed PV system with the issue of too low voltage in the
grid. The inverter recognized this as a problem in the grid and refused to be
grid connected. This occurred during a couple of days and is very expensive for
me as investor if the PV system does not work. I have been aware of the problem
with low voltage in the grid for some time and now it became clear to me, but
as long as nobody complains there is not a problem. I complained and got my
company to higher the voltage in the area.”
(Handler, 2011)
Handler adds that one consequence from this might be that the DSO must start to tune
the voltage. The second report occurred in Örnsköldsvik where they also alarmed about
the voltage, but this time it was too high. The reason was the contribution from solar
panels, which made the voltage rise at the customer. DSOs have before been used to
lower and lower voltage the further you go on the grid. Suddenly the situation has
changes and the DSO must review their grid and in reality increase the short circuit
power. The both situations are something we need to be aware of and train for before
photovoltaic systems become more spread says Handler (2011).
5.4 The future
5.4.1 The spread of small-scale distributed generation within 10 to 20 years
During the interview some critical remarks about small-scale wind power were said.
Björck (2011) said for instance that he does not believe much in small-scale wind power,
that he is quite skeptical. He mentions that you receive so much more per SEK putting
your money on a larger wind power. The potential from photovoltaics on the other
hand is bigger, due to the fact that the size of the module is not crucial. This view was
shared with Handler (2011) who believed in large off-shore wind power. He also
believes very much in photovoltaics and can see a huge potential there. Another
comment was from Dolhsäter (2011):
“Personally, I do not believe in small scale wind power, such as wind mills. We
have seen a number of small plants not functioning; they do not deliver the
promised power (many times fantasy numbers) and are not holding. One has
seen quality problems and even if it is getting better the prices has instead
increased being so expensive that it is impossible.”
The spread of small-scale distributed generation in the future is a pure political question
according to Bergerland (2011).
“…just look at Germany. They are the leaders of solar power even if they do not
have the best circumstances when it comes to the sun, but they have their
supporting system.”
(Bergerland, 2011)
47
Söder (2011) has a hard time seeing photovoltaics as the dominant solution, but it
seems as a decrease in price is coming on photovoltaic panels which brings potential.
Bergerland (2011) point out that the price on the photovoltaic modules has gone down
quite dramatically the last two years. And there is a continued pressure on prices on the
modules and soon the greatest cost will be the installation and the inverter. Bergerland
comment the solar market and says that there must be a further pressure on the prices,
especially in Sweden where the market is very immature. A solar panel in Sweden cost
50 % more in Sweden then in Germany, and it is all about the markets volume and
immaturity. There are no participants on the market today in Sweden that are efficient
in their processes; it is more of a homemade installation every time. In Germany they
talk about grid-parity 2014-2015, which means that the solar electricity price is the
same as the price on the electricity market without subventions. In Sweden it may be
around 2018-2020 and if we get there the market will grow on its own. Another thing
that also influences it is how fast and hard we integrations with northern Europe. A high
integration with for example Germany will give us electricity prices closer to German
prices. The Swedish electricity price will probably increase, which further amplify the
driving force towards having your own electricity production. The gain will increase.
“We at Fortum believe that solar electricity will come, it is just hard to tell
when, but I am sure that we will have solar electricity that is market oriented
within ten years.”
(Bergerland, 2011)
Niss (2011) discuss various aspects that influence the expansion of distributed
generation. She mention that is depends on how the question of electricity grid charges
is developed. The development is also influenced of the discussion about carbon dioxide
and the situation in Japan with the followed European discussion about closing down
nuclear power plants. Closing down nuclear plants demands for alternative solutions.
But still, customers must gain something from the small-scale electricity distribution, it
is not enough that Sweden or Europe gains on it, and if this happens an expansion can go
quite fast. Then you need rules and laws that are clear, because they are not today say
Niss (2011).
Hammar (2011) also talks about that the expansion is totally depended on political
decisions. The technology exits, but it depends if the politicians thinks this is so
important that they want to support it. Then you have to evaluate if this is going to
happen and he believe that the environmental concerns are going to be so central in a
couple of years that one will try everything to integrate renewable. This is if you look at
a European perspective he adds. From a Swedish perspective we have hydro power and
wind power, but from a European perspective there is a need for much more renewable
and there will be efforts to make sure that we have the supporting systems needed.
Hammar then believe that in ten years’ time there will be a good demand for small-scale
solutions both when it comes to wind and solar power.
Berling (2011) believes in a future with great deal of both large-scale and small-scale:
“If we focus on the technology of using the solar energy, used very little today,
then I rather add 30 years instead. I then believe that we are going to use the
solar energy a whole lot more.”
48
Widén (2011) adds on to the perspective that it depends if we can have net charge and if
the price of solar electricity is worth the same as the bought electricity, because
household will then actually gain from installing systems that will cover the electrical
load during the offset period for this net charge period. If we talk about monthly set-off
period, then you install systems that cover the electrical load during a summer month, a
month with highest production. So if the household would actually gain from it, then it
could be a boom within 10 years. He summarizes his discussions with the main factors
the spread depends on; a solution with net charge and for the prices to go down on solar
electricity.
“Even with net charge it is still too expensive to install photovoltaic systems
today, but with a net charge solution persons who really want to install systems
can install larger systems because it will be less costly. The load for buildings
used as for examples offices is better adjusted to production from photovoltaic,
for them it is enough if the prices goes down on the PV systems. They do not
need a net charge solution in the same way.”
(Widén, 2011)
5.4.2 Valuable areas for distributed generation in the future
Bixia believes that small-scale electricity production will be used by private persons, but
also corporations. Dolhsäter (2011) mention that Bixia has had interest about putting up
a photovoltaic park along the sea-front on the west-cost; a stand-alone system as a pure
investment. Bergerland (2011) on the other do not see it as a source to export current,
but to decrease the own local consumption.
Björck (2011) believe in photovoltaic but not in small-scale wind power. Small-scale
wind power gives such a small addition in electricity, it is the big ones that matters.
Bergerland (2011) point out the economics of scale with photovoltaic toward smallscale wind power and that it can be integrated in urban environment as for example
building integrated solutions where photovoltaic can be a precast element. You can then
have a faster gain because you substitute building material that itself have costs, says
Bergerland. Handler (2011) is during his interview very enthusiastic about photovoltaic
and believes a great deal in them, especially as solutions integrated into new buildings.
He also mentions the possibility to connect the photovoltaic system to a heat pump.
“I believe that municipality and the municipality buildings will be first in line
and develop solutions that are integrated into the buildings. Commercially I
think that new housing estate with already build in solar energy solutions in
the building shell is a really interesting and exiting area.”
(Hammar, 2011)
Östermark (2011) believes that small-scale electricity production is an important PR
and symbolic question that will be a valuable area for distributed generation in the
future. Bertling (2011) mention that small-scale distributed generation may have a
greater importance in the vehicle sector with electricity vehicles in the future, as a
solution from a balancing point of view, something also mentioned by Widén (2011).
The electrical vehicles give potential storage capacity without having to install storage
devices, for example batteries.
49
“Above all, I can see the small-scale distribution being used within household,
being used locally. I would like to put focus on that the objective is not do
deliver electricity to the grid but rather be self-contained. The small-scale
renewable generation will not be used for critical loads for instance hospital.
The large power plants such as hydro power and nuclear power are more costefficient and will go to our industries.”
(Bertling, 2011)
50
6 Case studies
6.1 Evaluation of wind mill from WindEn
During interviews and literature reviews about small wind power, the summarized
conclusion is that the size and height of the wind power plant have a great impact of the
amount of delivered electricity. The wind power plant should not be places in urban
areas. A wind mill from WindEn is therefore chosen, WindEn45; a wind mill that
according to the manufacturer is suited for farmers, private persons, companies and
communities with an open space (WindEn, 2011). Siemens is also supplying the
company with products, which is an additional reason for choosing WindEn 45. WindEn
45 comes with a tower from 18 to 36 m. With an average yearly wind speed of 6 m/s, the
output is about 106 000 kWh. Table 6.1 specifies technical data for WindEn 45. Figure
6.1 demonstrates the typical power curve for WindEn 45 and Figure 6.2 shows the
energy curve.
Specification for WindEn 45
Standards
IEC 61400-2:2006
Rated Power
45 kW
Rated Wind Speed
13 m/s
Operational wind speed
Maximum allowed wind
speed
3,5 m/s
Number of blades
3
Diameter
14.6 m
Rotor Area
166 m2
Number of phases
3, 400 VAC
Frequency
Electrical network
connection
50 Hz
Power Control
Stall effect regulating
Double fail-safe spring applied
brake
Brakes
52.5 m/s
Yes
3 blade tip brakes
Revulotions
60 r.p.m.
Possible towers
Pipe tower or lattice tower
Table 6.1 Specification for WindEn 45 (WindEn, 2011).
51
Figure 6.1 Power curve for WindEn 45 (WindEN, 2011).
Figure 6.2 Energy curve for WindEn 45 (WindEN, 2011).
Annual average wind speed is important for the energy output, which can be seen in
Figure 6.2. Wind data characteristic is therefore used for siting analysis, where Hans
Bergström (2007) wind mapping is used. Figures 6.3-6.5 shows Bergström’s wind
mapping of Sweden at different altitudes. The assumption in this evaluation is that a
farmer in Norrtälje Municipality is the potential customer. Therefore, in Figure 6.6, the
area of interested is zoomed in at the wind altitude of 49 m. Average wind speed at 49
m is around 5,5 – 6 m/s in majority of this area. The WindEn 45 tower will not reach 49
m, so average wind speed is expected to be lower. Analysing Hedströms wind mapping
together with normal wind condition data from SMHI (see Appendix B), wind speed of 5,
6 and 7 m/s is chosen to examine various cases. It is assumed that the farmers total
electricity need for the farm is 90 000 kWh per year, where 20 000 kWh per year is for
the household and 70 000 kWh for the company.
52
Figure 6.3 Average wind speed above altitude
of 49 m above the zero plane displacement.
Figure 6.4 Average wind speed above altitude
of 72 m above the zero plane displacement.
Figure 6.5 Average wind speed above altitude
of 103 m above the zero plane displacement.
Figure 6.6 Zoomed in area for average wind
speed above altitude of 49 m above the zero
plane displacement.
53
The farmer is taking a bank loan with fixed rate mortage paying once a year. The yearly
payment, c, is calculated with the following formula (1):
c
P0
r
n
yearly payment [SEK]
amount borrowed [SEK]
interest rate
number of payment during the loan
c  P0 
r
1  1  r 
n
(1)
The loan is for 990 000 SEK with a pay-back time of 10 years and a five percent interest
rate where the farmer is allowed to withdraw 30 % of the interest rate by law. Table 6.2
summarizes conditions for the loan.
Cash contribution [SEK]
110 000
Loan [SEK]
990 000
Interest rate [%]
Pay-back time in years
Tax deduction [%]
Table 6.2 Loan conditions used for the case study.
5
10
30
The investment calculation is based on electricity prices from Fortum (Fortum, 2011)
together with aggregated values of Nord Pool’s spot price (Nord Pool Spot, 2011).
Estimated increased electricity price per year is based on data from Statics Sweden
(Statistiska centralbyrån, 2011). Calculated values are presented in Appendix C.
Produced electricity primarily covers the household electricity need, thereafter the rest
goes to the company and any surplus electricity is sold. Total electricity production is
therefore distributed between replace purchased private electricity, business operation
electricity and sold electricity. Distribution is different in examined cases. The
percentage distribution is in the investment cost calculation, Table 6.3, noted as x, y and
z. Table 6.4 shows a clarification of exact distribution in each case.
In the investment cost calculation a running charge is assumed from the sixths year with
an upward adjustment for inflation with three percent per year which is used by
WindEn in their information for investment cost calculations. In Table 6.3, the
investment cost and running charge are data from WindEn. Produced energy per year
for an annual average wind speed is based on the energy curve for WindEn 45, see
Figure 6.2. The result of the investment cost calculations are presented in Chapter 7.2.
54
Investment calculation WindEn 45,
price excluding VAT
INVESTMENT COST
Cost for WindEn 45 and 36m lattice tower including other estimated costs*
ANNUAL AVERAGE WIND & PRODUCED ENERGY
Case I
Case II
Case III
ELETRICITY PRICE BUY/SELL
Replace purchased private electricity
Replace purchased business operation electricity
Sold electricity
Revenue REC on all produced electricity
Electricity price increase per year
[SEK]
1100000
Annual average
wind [m/s]
5
6
7
Produced energy per
year [kWh/year]
68061
105780
142320
[SEK/kWh]
1,33
1,05
0,38
0,3
Percentage [%]
x**
y**
z**
5,5
RUNNING CHARGE
[SEK/kWh]
Percentage [%]
Service cost
0,05
Increased service cost per year
3
*Other estimated cost depends on the customer possibilities to help with foundation, shipping, mobile crane,
installation and cables. It is assumed that the customer will not have any possibilities to help.
**Percentage of the total produced electricity going towards this purpose
Table 6.3 Investment calculations for WindEn 45.
Case
Average wind speed
x [%]
y [%]
z [%]
[m/s]
Total produced electricity
[kWh/year]
I
5
29
71
0
68061
II
6
19
66
15
105780
III
7
14
49
37
142320
Table 6.4 Distribution between replace purchased private electricity, replaces purchases business
operation electricity and sold electricity for the different cases.
55
6.2 Presentation of PV system simulation
There are different factors that have an impact on the energy production from a PV
system, for example, shading, temperature, gradient and orientation. The aim of this
simulation was not to evaluate the impact of these different factors, the objective was to
get an idea about the amount of energy production and the cost involved.
The following assumptions are therefore made:




There are no obstructions on the accessible surface area and the accessible
surface is not shaded at any time during the day from the surroundings such as
from trees.
The orientation of the PV systems is towards the south, which is the optimal
direction for PV systems, with a gradient between 35 and 50 degrees (Stridh &
Hedström, 2011).
The case study is geographically located in Stockholm and climate data for
Stockholm can be found in the PVsyst 5.42 program.
The roof construction and buoyancy can manage the PV system design. The
system is connected to the existing grid and owners of the house are not doing
any installation work on their own.
Case Study ”the Swedish Villa”: The average small
Swedish house is a 1.5-storey house with pitched
roof, basement and heated area, Atemp, of 160 m2
(Boverket, 2010). It is assumed that the roof
grading is 40 degrees and total available roof
surface is 92 m2 leaving 46 m2, available roof
surface facing south. The roof is planned to be
covered with 32 m2 solar panels.
The simulation uses the project design option in
PVsyst V5.42 where system parameters such as
solar modules, inverter, geographical location,
orientation and near shadings have been chosen.
To compare economic data received from the
Figure 6.7 The Swedish Villa.
Swedish company Solaris, a reseller and
marketer of PV systems, the preliminary design option has also been used which
contains a very coarse estimation of the cost for modules, other components, mounting
etc. This is more to get an idea about the proportions of the different cost towards each
other. In this option the designer chose general system specification and cannot choose
a specific solar module or inverter. The following has therefore been used to get a result:




Module Type: Standard
Technology: Monocrystalline cells
Mounting disposition: Tilt roof
Ventilation property: Free standing.
56
6.2.1 Choice of PV modules and inverter
There are a variety of PV modules on the market, with manufacturers such as Sharp,
Suntech, Hareon solar and Q.cell. The most common module is made out of crystalline
silicon with the dimensions of 1.5 -1.7 m long and 0.7 -1 m wide with a peak power
between 180 and 230 W (Kreutzman & Siemer, 2010). The module used for this
simulation is HR-210W/18V from the manufacturer Hareon Solar. Module size is 1636
mm wide and 992 mm high with a weight of 18 kg or about 11.1 kg/m2. It has the
efficiency of 12.94 percentage and peak power of 210 W, where 1 kW corresponds to
about 7.7 m2 pre-mounted active PV module surface (GE4ALL, 2011).
It is the peak power of the system that decides the dimensions of the inverter; it is
possible to either use several small inverters or fewer but larger inverters. The inverter
is connected to the Swedish grid; therefore only inverters operating at the frequency of
50 Hz are of interest.
A PV system package sold by Solarit is simulated and therefore inverters included in the
package are chosen, which are inverters from the manufacturer Steca. The Solarit PV
system package is a 4200 W (20x210 W) grid connected system which includes:






20 solar panels of the model HR-210W/18V
1 Steca grid 2000 Master inverter and 1 Steca grid 2000 Slave inverter together
with wall mount
120 m DC cable to be used between the PV panels and the inverter
DC disconnector
Electricity meter
Galvanized steel profiles with screws/nuts to attach the profiles onto the ceiling
bracket, together with clamp mounts to the panels. Ceiling brackets are not
included, but can be bought for 150-250 SEK per piece, depending on the roof.
This calculation uses the price of 250 SEK with the recommendation of 36 pieces,
which becomes the total amount of 9 000 SEK.
The total price of the package is 221 800 SEK including ceiling brackets. Shipping and
installation are not included. Technical data and information about the inverts used in
the simulation can be found in Table 6.5.
Product
Steca Grid 2000
Master
Steca Grid 2000
Slave
Nominal AC
Power
[kW]
2,0
Efficiency
Euro-ETA* / max
[%]
93,3 / 95,0
Dimension
width/height/depth
[mm]
542 / 351 / 140
Weight
[kg]
11
2,0
93,5/95,0
535 / 226 / 140
9
*Euro-ETA is a balanced efficiency taking into account that the inverter does not always operate at full
power.
Table 6.5 Technical data and information about Steca Grid 2000 inverters.
57
7 Results
The section presents the main results from interviews, evaluation of the wind mill
WindEn 45 and PV simulations.
7.1 Interviews
The main results from interviews are in this section summarized. Possibilities and
benefits together with problem and hindrance about the impacts from distributed
renewable generation have been drawn from interviews and are listed in Figure 7.1 and
Figure 7.2.
Reduce CO2
emission
Relieve some of
the necessity to
invest in
transmission
system expanssion
Reduce losses
PV can go quite
fast to get on the
spot and therefore
become a potential
tool
Possibilities
and
benefits
Increase the
awareness and
commitment
Figure 7.1Possibilities and benefits from distributed generation.
Economic issues
The costs are big for
connecting small-scale
distributed generation
to the grid, who
should pay for it?
Mismatch between
production and
consumption
Increased complexity
of problems around
protection when flow
goes two ways
Political and legal
issues
Problems
and
obstacles
Electricity certificate
system not adapted
for small distributed
generation
Figure 7.2 Problems from and obstacles for distributed generation.
58
The main incentives for the development and spread of small wind power and
photovoltaics for market participants such as prosumer, distributed system operator
(DSO) and power trading company (PTC) are summarized in Figure 7.3.
Prosumer



DSO and PTC


Environmental concerns
Symbolic value
Become more independent

Customers wants it
Policy and image: Profile themselves as
green and keep a good relationship
with customers
DSOs might have a decrease in losses,
decrease exchange with superincument
grid and avoid lean-tos of the grid.
Figure 7.3 Main incentives for the development and spread for prosumers, DSO and PTC.
Figure 7.4 shows the main topics mentioned during interviews regarding valuables
areas of distributed generation such as small wind power and PV in the future.
Valuables areas
in the future
Cover the own
consumption
•Corporations
•Municipality
•Houses
PR and
symbolic issue
Solutions
together with
electrical
vechiles
Building
integrated
photovoltaics
Figure 7.4 Valuable areas for distributed generation in the future mentioned during interviews.
7.2 WindEn evaluation
Results of the investment cost calculation for a WindEn 45 are presented in two graphs.
First graph indicates the accumulated profit per year for the three cases with different
average annual wind speed, see Figure 7.5. The profit is the value of the produced
electricity from the wind mill in SEK minus the yearly payment for the loan, the service
cost and the meter cost. First year also includes the cash payment of 110 000 SEK.
The second graph indicates the break-even point (BEP), see Figure 7.6, where total value
for the total loan payment including cash payment is 1 300 390 SEK. The break-even
point has been reached under year 11 for case I, year 9 for case II and finally under year
59
8 for case III. All calculations made to plot the two graphs, Figure 7.5 and Figure 7.6, are
shown in Appendix D.
Accumulated Profit [SEK]
5 000 000
4 000 000
3 000 000
Case I (5 m/s)
2 000 000
Case II (6 m/s)
Case III (7 m/s)
1 000 000
0
1
3
5
7
9
11 13 15 17 19 21
-1 000 000
Year
Accumulated produced electricity
[SEK]
minus meter and service cost
Figure 7.5 Accumulated profit for the three cases.
3500000
Case I (5 m/s)
3000000
2500000
Case II (6 m/s)
2000000
1500000
Case III (7 m/s)
1000000
Total payment for
loan including cash
payment
500000
0
Year
Figure 7.6 Accumulated produced electricity minus meter and service cost for the three
cases.
7.3 PV simulation
The simulation parameters and the main results from the project design option in the PV
simulation are all included in Appendix E. The main simulation result is produced
energy per year, which is 3923 kWh/year. Figure 7.7 shows normalized production per
day for different months, which indicates that the prosumer receives the largest amount
of produced electricity during the summer months.
60
Figure 7.7 Normalized production (per installed kW): Nominal power 4.2 kW.
The system under evaluation costs 221 800 SEK, excluding shipping and installation;
with a subsidy of 60 % the price is 88 720 SEK. Preliminary design option gives for a
similar PV system layout, as the one from Solaris, a total cost of 278 915 SEK including
shipping and installation but not VAT. Total price with subsidiary and VAT is 139 458
SEK, if we exclude transport/mounting the total price is 111 477 SEK. Table 7.1 shows
the economic gross evaluation from PVsyst V5.42 and Figure 7.8 indicates the
proportions of different cost. The difference between Solaris system cost and PVsysts’
gross evaluation excluding the transport/mounting is 22 757 SEK.
Percent of
Price
total investment
[SEK]
[%]
Module cost
159 252
57
Support cost
35 389
13
Inverter and wiring
28 312
10
Transport/mounting
55 962
20
Total investment
278 915
100
Table 7.1 Economic gross evaluation performed by the PVsyst V5.42 using preliminary design
option.
61
Module cost
57%
20%
13%
10%
Transport/Mounting
Support cost
Inverter and wiring
Figure 7.8 Estimated proportions between different cost from the preliminary design option.
Table 7.2 shows the investment calculation used for the Solarit PV system, which
includes value for produced energy per year and an estimated shipping and installation
cost of 20 % of the total investment cost. All produced electricity is assumed to be used
by the household.
Investment calculation Solarit PV
system, price including VAT
INVESTMENT COST
Solarit grid-connected PV system package 4200 W (20x2100W)*
Estimated shipping and installation (20 % of total investment cost)
Subsidiary of 60 %
Total investment cost
PRODUCED ENERGY
[SEK]
221800
55450
-166350
110900
[kWh/year]
Produced energy per year
ELETRICITY PRICE BUY/SELL
Replace purchased private eletricity
3923
[SEK/kWh]
Percentage [%]
1,33
100**
Electricity price increase per year
RUNNING CHARGE
5,5
[SEK/kWh]
Service cost
Increased service cost per year
Percentage [%]
0
0
*Shipping and installation are not included.
**Percentage of the total produced electricity going towards this purpose
Table 7.2 Investment calculations for the Solarit PV system used for economical evaluation.
62
Figure 7.9 demonstrates the result from the economical evaluation using data in Table
7.2. For further information about data used for the plot, see Appendix F. The customer
is assumed not to take any loans for the investment in the PV system and an
accumulated profit is calculated per year. By plotting the total investment of 110 900
SEK as a red dashed line the break-even point is indicated when the totalt investment
intersects with the accumulated produced electricity, which is during year 15.
350000
300000
250000
SEK
200000
150000
Accumulated
produced electricity
100000
Accumulated profit
50000
Total investment
0
-50000 1 3 5 7 9 11 13 15 17 19 21 23 25
-100000
-150000
Year
Figure 7.9 Result from economical the evaluation of the Solarit PV system package.
63
8 Conclusion and discussion
This thesis has given a brief technical description of both small wind power and
photovoltaics, together with a literature review why the future grid, so called smart grid,
is of importance for the distributed generation. Today’s market for distributed
generation has also been described; including electricity market participants, various
control instruments, how the metering and settlement works today. The main common
incentive today for the development and spread of small wind power and photovoltaics
for market participants such as prosumer, distributed system operator and power
trading company is the symbolic value of for example showing environmental
commitment. Possibilities and benefits from distributed renewable generation drawn
from the interviews are:




reduce CO2 emission;
increase the awareness and commitment;
relieve some of the necessity to invest in transmission system expansion and
reduce losses;
PV can go quite fast to get on the spot and therefore become a potential tool.
The conclusion can be drawn that the market situation is complicated for the producing
consumer; there are various market participants to contact if one wants to become a so
called prosumer and it is hard to know who to contact. The information is also wide
spread and there is no common forum for the small-scale electricity producers. Maybe
something that could be in consideration for the future.
If prosumers want to sell their surplus electricity they do not receive much for it and
photovoltaic generation for households has a problem today due to mismatch between
production and consumption. It has been and still is an ongoing debate about solutions
around net metering or some kind of offset between consumed and produced electricity,
where the latest news is that there might be plans for a new investigation. We will
probably not see a solution for offset this year and maybe not for the following year
either. Investment subsidiary for grid connected PV plants runs out 2011 and what
happens after that is still unclear. It can be concluded from the interviews that politics
control the development and spread of small scale electricity solutions such as wind
power and photovoltaic. The market today is very unclear and in Sweden we lack the
politician leadership when it comes to decision making and clear communication about
small-scale electricity production. The energy law is thin and there is a need to revise it.
Another issue that needs to be looked over is the REC system, which is not adapted for
small distributed renewable generation. These producers do not receive the benefit
from this support.
This thesis includes a presentation of important power quality considerations for the
interconnection of DG resources to distribution network. No conclusions can be drawn
regarding which are the main power quality issues when interconnection distributed
generation. In order to do this, a simulation of the network in mind must be conducted.
Power quality issues are dependent of the network system as a whole; technical
properties of the generation, load profile, properties of the grid and is often a matter of
cost and can be prevented with different technical solutions. A question one can ask
yourself is also who is responsible for the power quality problem. Is it the producer
64
causing for example changes in frequency or the device owner who experience the
frequency shift as a problem?
One thing that can be stated is that distributed electricity production such as wind
power and photovoltaics demands that the electricity grid can manage both fast
production variations and harmonics from power electronics. There is also an increased
complexity of problems around protection when electricity flow goes two ways.
Increased security and communication are a necessity, which is a part of the smart grid.
It can also be stated that the weaker the grid is the greater are the voltage fluctuations.
As mentioned by Gomez Targarona & Morcos (2007); some power quality phenomena
are very noticeable when they take place in weak systems and pass practically
unnoticed when they happen in strong distribution networks.
All of the interviewed persons are aware of the possible problem of power quality, but
there is so for little or no knowledge how the Swedish grid is affected by a large increase
of DG. Companies like Vattenfall, Fortum, Beta, Utsikt and Göteborgs Energi are all
involved in projects to learn more. They all need to gather knowledge how to deal with
small DG both in technical aspects such as power quality and how to deal with the
customers practically.
The spread of both small scale wind and photovoltaics in Sweden is very small today.
Table 8.1 shows the main findings about size of today’s market and future potential
when it comes to PV and small wind power. Majority of the interviewed persons believes
more in PV that in small wind power due to facts such as size of the module it not crucial
for PV, you receive so much more per SEK investing in a larger wind power plant and
small wind power do not deliver promised power. Various interviewed persons believe
that there will be a good demand for PV systems solutions in ten years’ time, but the
spread depends on for example political decisions and economic factors.
PV
Small
wind
power
Today
8,8 MW, where 3,6 MW is
grid-connected PV systems
Potential
37 TWh,
370 km2
favorable
oriented
roof
surface
Comment
To create a commercial self-supporting market:
 high cost reduction
 increased electricity price
 net charge solution
 technology development
Installed power ≤44 kW:
2 MW
Installed power ≤1500 kW:
535 MW, 1,1 TWh
11 TWh
Specific obstacles for small wind power:
 Wind power is size-dependent;
requires height for good wind condition
and good wind conditions is essential
for economic feasibility, also not
optimal to build in urban areas
 May requires building permit
Spread is driven by:
 Large interest from community
 Environmental concerns
 Political decisions
 Discussions about closing down nuclear power and the need to find alternative solutions
 Customers must gain something from it
 Economic factors
Table 8.1 Summary of the market today and future potential for PV and small wind power.
65
The two case studies in the thesis show the investment sizes and the importance of
different factors. Good wind conditions are a very important factor when it comes for
the investment of a wind mill to be profitable. Depending on the average wind speed the
break-even point differed between 8 and 11 years. The accumulated profit on the other
hand differed and was positive between 3 and 11 years, which once more show the
importance of wind condition. The question is if the WindEn 45 with the highest point of
44,8 meter is enough. The PV case study “the Swedish Villa” concludes that main
incentive for installing a PV system is not for economic reasons. It also indicates that
prices need to decrease. A PV system is still very expensive, but costs can be lowered if
the house owner is prepared to do some of the installation work himself. In the Swedish
Villa case study the house owner will make a profit from the PV system in year 15 and it
is also the year when the break-even point is reached. This is with the assumption that
all the electricity is used within household and that there is no mismatch between
production and consumption.
I believe that the market for small-scale electricity production will change, which can be
seen by more power trading companies offering to buy produced electricity. Interest is
growing every day, which can be seen in the latest media interest in the subject. If we
wish to see a further development of small-scale renewable technologies, the
community must invest money in research and different economic supports to stimulate
the market. As mentioned before; the government is going to make an investigation
about solution around some kind of offset between the production and consumption, the
question is when we will see the result. Further increased pressure from the community
will hopefully speed up the process, but at the same time it is important to think all
aspects through. Who should have the benefit from it? Why should only small electricity
production facilities get benefit from an offset or where goes the limit? The issue of net
charge may implicate improved economy for electricity users with self-generation and
lead to an increased demand for small-scale distributed generation, but at the same time
the cost involved to connect the generation has to be paid by someone. Who should pay
for it? Who will get the benefit from it? Voltage and frequency varies more in a weak and
autonomous grid, but the prerequisites to keep required voltage and frequency levels
are still good with today’s technology, but once more it is a question of economic.
I believe that the expansion of wind power will mainly be done by wind cooperatives
and on large-scale level due to factors such as poor wind conditions in urban areas, wind
tower heights is vital and difficulties in general to build in urban areas. To compare with
photovoltaic, where the size is scalable. One thing is for sure, the energy market is
changing and an exciting future lies ahead.
66
9 Future work
In order to evaluate potential market in Sweden the author recommends further studies.
A comparison with other countries could give an indication for what is to aspect in
Sweden. This could also show different scenarios what can happen depending on which
supporting system the country’s politicians decide to have.
In order to gain knowledge about power quality issues, a case study simulation should
be conducted looking at a specific part of the grid, as a suggestion an urban and rural
grid to compare the results in between. The case study could investigate what happens
with the power quality if a whole neighborhood connects themselves to the grid with PV
systems or if several farmers connect a wind mill each on a weak grid. There are also
interesting questions around how good power quality there is a need for.
On the market there exists easy economic calculation tools for PV system to get a first
idea how much you can gain from the investment, but there are no one for small-scale
wind power. An economic tool for small scale wind power should be interesting in order
to actually have an idea how much you receive back from an investment.
67
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Appendix
Appendix A: IEEE STD 1159 for low voltage grid
The following table gives the requirements of EN 50160 (2009); Voltage characteristics
of electricity supplied by public distribution systems.
General requirements (except for frequency) are:
 At least one week of measurement
 10 min average rms values
 95 % of data shall fall within limits
Parameter
Power frequency
Magnitude of the supply
voltage
Supply voltage variations
Voltage level variations
Rapid voltage changes
Flicker
Supply voltage sags
Short interruptions of
supply voltage
Long interruptions of
supply voltage
Temporary, power
Frequency overvoltages
Transient overvoltages
Supply voltage
unbalance
Harmonic voltage
EN 50 160 requirements
Mean value of fundamental measured over 10 s:
±1 % (49.5-50.5 Hz) for 99.5 % of week
-6 % / +4% (47-52 Hz) for 100 % of week
±10 % for 95% of week
±10 % for 95 % of week
±10 % for 95 % of week
Level changes ≤ 5 % normal, > 10 % infrequently
Plt ≤ 1 for 95 % of week
Majority: duration < 1 s, depth < 60 %
Locally limited sags caused by load switching: 10-50 %
Duration <= 3 min: few tens – few hundreds/year
Duration 70 % of them < 1s
Duration > 3 minutes: <10 – 50/years
< 1.5 kV rms
Generally < 6 kV, occasionally higher; rise time: ms-µs.
≤2%
≤ 3 % in some locations
individual harmonics: requirements not included in this
table
76
Appendix B: SMHI climate map.
Figure Appendix 2. Climate map to illustrate wind conditions for the normal period 1961-1990 at
50 m height above the ground.
77
Appendix C: Estimated increase of electricity price.
Total electricity price include: trading price, grid price, electricity certificate price, taxes,
and VAT. All the prices are given in öre/kWh for customers types.
Group
Yearly consumption [kWh]
Da
600
Db
1 200
Dc
3 500
Dd
7 500
De
20 000
Table Appendix 3.1 Definition group Da-De.
Household consumers, total electricity price
[öre/kWh]
Year
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Month
January
January
January
January
January
January
January
January
January
January
January
Da
197.7
204.4
201.3
193.1
199.3
229
271.8
289.5
273.8
282.1
305.6
Db
130
136.3
132.4
129.5
134.3
153.9
182.5
194.2
184.9
192.5
215.1
Dc
85.6
91.5
87.1
87.7
91.6
104.5
123.8
131.6
126.4
133.6
155.6
Dd
83.4
92.6
84.3
81.8
86.3
97
113.6
122.6
118
123.2
141.4
De
70.1
73.6
75.1
72.7
74.8
86.9
102.3
111.9
108.1
113.9
129.2
Percentage change from the previous year starting with 1997
Year
Da
Db
Dc
Dd
1997
1.000
1.000
1.000
1.000
1998
1.034
1.048
1.069
1.110
1999
0.985
0.971
0.952
0.910
2000
0.959
0.978
1.007
0.970
2001
1.032
1.037
1.044
1.055
2002
1.149
1.146
1.141
1.124
2003
1.187
1.186
1.185
1.171
2004
1.065
1.064
1.063
1.079
2005
0.946
0.952
0.960
0.962
2006
1.030
1.041
1.057
1.044
2007
1.083
1.117
1.165
1.148
1.0470525 1.0541514 1.0642839 1.0574655
Average increase per year
Aggregated value for all
groups
De
1.000
1.050
1.020
0.968
1.029
1.162
1.177
1.094
0.966
1.054
1.134
1.0654083
1.058
78
Consumption
category
IA
IB
IC
ID
IE
IF
Yearly consumption
[MWh]
< 20
20 - < 500
500 - < 2 000
2 000 - < 20 000
20 000 - < 70 000
70 000 - < 150 000
Table Appendix 3.2 Definition group IA-IF.
Industry consumers, total electricity price
Year
Month
Ia
Ib
Ic
1997
January
61.9
59.4
53.6
1998
January
60.5
59.9
51.5
1999
January
56.4
57.2
49.6
2000
January
47.8
48
44.3
2001
January
55.5
56.6
50.4
2002
January
51.2
51.8
46.1
2003
January
80.7
81.3
74.7
2004
January
63.3
63.8
56.9
2005
January
63.6
61.7
52.1
2006
January
77.3
75.3
64.8
2007
January
81.7
80
70.6
Id
46.3
42.3
40.3
39.4
45.3
43.4
73
54
48.6
61.5
63.6
Ie
36.9
34.2
31.6
32.2
37.3
37.6
66.9
47.5
42.3
55.2
57.3
If
35
32.7
28.8
27.5
31.2
33.5
64.6
44.5
38.9
51.8
53.8
Percentage change from the previous year starting with 1997
Ia
Ib
Ic
Id
Ie
Year
1997
1.000 1.000
1.000 1.000 1.000
1998
0.977 1.008
0.961 0.914 0.927
1999
0.932 0.955
0.963 0.953 0.924
2000
0.848 0.839
0.893 0.978 1.019
2001
1.161 1.179
1.138 1.150 1.158
2002
0.923 0.915
0.915 0.958 1.008
2003
1.576 1.569
1.620 1.682 1.779
2004
0.784 0.785
0.762 0.740 0.710
2005
1.005 0.967
0.916 0.900 0.891
2006
1.215 1.220
1.244 1.265 1.305
2007
1.057 1.062
1.090 1.034 1.038
1.048 1.050
1.050 1.057 1.076
Average increase per year
Aggregated value for all consumption
categories
Ig
31.2
28.6
25.1
24.4
27.4
30.3
60.7
40.7
35.1
48.1
50.2
If
1.000
0.934
0.881
0.955
1.135
1.074
1.928
0.689
0.874
1.332
1.039
1.084
Ih
30.9
28.3
24.9
24.9
28.4
30.9
61
41.2
35.1
48.2
50.1
Ii
29.1
26.6
23.3
23.1
26
29.1
59.2
39.2
32.9
46
47.9
Ig
1.000
0.917
0.878
0.972
1.123
1.106
2.003
0.671
0.862
1.370
1.044
1.095
Ih
1.000
0.916
0.880
1.000
1.141
1.088
1.974
0.675
0.852
1.373
1.039
1.094
Ii
1.000
0.914
0.876
0.991
1.126
1.119
2.034
0.662
0.839
1.398
1.041
1.100
1.0726
Electricity price increase per year is assumed to be 5.5 %
The average increased electricity price for industry consumers between 1997 and 2007 have 7.3 % per year
and for household consumers 5.8% per year. It is therefore reasonable to assume an electricity price increase of
5.5 % per year.
79
Elspot price
Year
Price
[SEK/MWh]
2010
542.53
2009
392.81
Average spot price 40.5 öre/kWh
Average yearly spotprice calculated from
2008
491.55
2005 to 2010 is about 40.5 öre/kWh and
2007
280.13
2006
445.38
this reference value is used for calculating the
compensation price for sold electricity from
Fortum.
2005
276.45
Average
404.81
80
Appendix D: Results for investment cost evaluation of WindEn 45.
Case I: Average wind of 5 m/s
Investment calculation for WindEn 45, values in SEK.
Meter
cost
Year Payment Prod el [SEK]
Service
2 pieces
Accumulated produced
electricity [SEK]
Accumulated
minues
Revenue
0
profit
meter and service cost
0
Total Cost
Payment +
Service +
Meter
0
1
119 039
97 593
0
4 000
-21 446
-135 446
93 593
233 039
2
119 039
102 961
0
4 000
-16 078
-155 524
192 554
123 039
3
119 039
108 624
0
4 000
-10 415
-169 939
297 178
123 039
4
119 039
114 598
0
4 000
-4 441
-178 380
407 775
123 039
5
119 039
120 901
0
4 000
1 862
-180 519
524 676
123 039
6
119 039
127 550
6 378
4 000
2 134
-182 385
641 849
129 416
7
119 039
134 566
6 728
4 000
8 798
-177 586
765 686
129 767
8
119 039
141 967
7 098
4 000
15 829
-165 757
896 555
130 137
9
119 039
149 775
7 489
4 000
23 247
-146 510
1 034 841
130 528
10
119 039
158 013
7 901
4 000
31 073
-119 437
1 180 953
130 940
11
0
166 703
8 335
4 000
158 368
34 931
1 335 321
12 335
12
0
175 872
8 794
4 000
167 078
198 010
1 498 399
12 794
13
0
185 545
9 277
4 000
176 268
370 277
1 670 667
13 277
14
0
195 750
9 787
4 000
185 962
552 239
1 852 629
13 787
15
0
206 516
10 326
4 000
196 190
744 430
2 044 819
14 326
16
0
217 874
10 894
4 000
206 981
947 410
2 247 800
14 894
17
0
229 857
11 493
4 000
218 365
1 161 775
2 462 164
15 493
18
0
242 500
12 125
4 000
230 375
1 388 150
2 688 539
16 125
19
0
255 837
12 792
4 000
243 045
1 627 195
2 927 584
16 792
20
0
269 908
13 495
4 000
256 413
1 879 608
3 179 997
17 495
21
0
284 753
14 238
4 000
270 515
2 146 123
3 446 513
18 238
22
0
300 415
15 021
4 000
285 394
2 427 517
3 727 906
19 021
23
0
316 937
15 847
4 000
301 090
2 724 607
4 024 997
19 847
24
0
334 369
16 718
4 000
317 650
3 038 258
4 338 647
20 718
25
0
352 759
17 638
4 000
335 121
3 369 379
4 669 769
21 638
26
0
372 161
18 608
4 000
353 553
3 718 932
5 019 322
22 608
27
0
392 630
19 631
4 000
372 998
4 087 930
5 388 320
23 631
28
0
414 224
20 711
4 000
393 513
4 477 444
5 777 833
24 711
29
0
437 007
21 850
4 000
415 156
4 888 600
6 188 990
25 850
30
0
461 042
23 052
4 000
437 990
5 322 590
6 622 980
27 052
81
Case II: Average wind of 6 m/s
Investment calculation for WindEn 45, values in SEK.
Meter
cost
Accumulated
Prod el
Year Payment [SEK]
Service 2 pieces
Revenue
profit
0
Accumulated
produced
electricity [SEK] minus
meter and service cost
Total Cost
Payment +
Service +
Meter
0
0
1
119039
138018
0
4000
18979
-95021
134018
233039
2
119039
145609
0
4000
26570
-72450
275628
123039
3
119039
153618
0
4000
34579
-41871
425246
123039
4
119039
162067
0
4000
43028
-2843
583313
123039
5
119039
170981
0
4000
51942
45098
750293
123039
6
119039
180385
9019
4000
52326
93425
917658
132058
7
119039
190306
9515
4000
61751
151176
1094449
132554
8
119039
200772
10039
4000
71695
218871
1281183
133078
9
119039
211815
10591
4000
82185
297056
1478407
133630
10
119039
223465
11173
4000
93253
386309
1686698
134212
11
0
235755
11788
4000
223968
606276
1906666
15788
12
0
248722
12436
4000
236286
838562
2138952
16436
13
0
262402
13120
4000
249282
1083844
2384233
17120
14
0
276834
13842
4000
262992
1342836
2643225
17842
15
0
292060
14603
4000
277457
1616292
2916682
18603
16
0
308123
15406
4000
292717
1905009
3205398
19406
17
0
325070
16253
4000
308816
2209825
3510215
20253
18
0
342948
17147
4000
325801
2531626
3832016
21147
19
0
361811
18091
4000
343720
2871346
4171736
22091
20
0
381710
19086
4000
362625
3229971
4530360
23086
21
0
402704
20135
4000
382569
3608540
4908929
24135
22
0
424853
21243
4000
403610
4008150
5308539
25243
23
0
448220
22411
4000
425809
4429959
5730348
26411
24
0
472872
23644
4000
449228
4875187
6175577
27644
25
0
498880
24944
4000
473936
5345123
6645512
28944
26
0
526318
26316
4000
500002
5841125
7141515
30316
27
0
555266
27763
4000
527502
6364628
7665017
31763
28
0
585805
29290
4000
556515
6917143
8217532
33290
29
0
618025
30901
4000
587123
7500266
8800656
34901
30
0
652016
32601
4000
619415
8115681
9416071
36601
82
Case III: Average wind of 7 m/s
Accumulated
produced
Investment calculation for WindEn 45, values in SEK.
Meter
cost
Year Payment Prod el [SEK]
Service 2 pieces
Accumulated
electricity [SEK] minus
Revenue
profit
meter and service cost
0
Total Cost
Payment +
Service +
Meter
0
0
1
119 039
162 567
0
4 000
43 528
-70 472
158 567
233 039
2
119 039
171 509
0
4 000
52 470
-22 002
326 076
123 039
3
119 039
180 942
0
4 000
61 903
35 901
503 018
123 039
4
119 039
190 893
0
4 000
71 854
103 755
689 911
123 039
5
119 039
201 393
0
4 000
82 354
182 109
887 304
123 039
6
119 039
212 469
10 623
4 000
82 807
260 916
1 085 149
133 662
7
119 039
224 155
11 208
4 000
93 908
350 824
1 294 097
134 247
8
119 039
236 483
11 824
4 000
105 620
452 444
1 514 756
134 863
9
119 039
249 490
12 475
4 000
117 977
566 421
1 747 772
135 513
10
119 039
263 212
13 161
4 000
131 012
693 433
1 993 823
136 200
11
0
277 689
13 884
4 000
263 804
953 238
2 253 627
17 884
12
0
292 962
14 648
4 000
278 313
1 227 551
2 527 941
18 648
13
0
309 074
15 454
4 000
293 621
1 517 172
2 817 561
19 454
14
0
326 074
16 304
4 000
309 770
1 822 942
3 123 331
20 304
15
0
344 008
17 200
4 000
326 807
2 145 749
3 446 139
21 200
16
0
362 928
18 146
4 000
344 782
2 486 531
3 786 920
22 146
17
0
382 889
19 144
4 000
363 745
2 846 275
4 146 665
23 144
18
0
403 948
20 197
4 000
383 751
3 226 026
4 526 415
24 197
19
0
426 165
21 308
4 000
404 857
3 626 883
4 927 272
25 308
20
0
449 604
22 480
4 000
427 124
4 050 007
5 350 396
26 480
21
0
474 332
23 717
4 000
450 616
4 496 622
5 797 012
27 717
22
0
500 421
25 021
4 000
475 400
4 968 022
6 268 412
29 021
23
0
527 944
26 397
4 000
501 547
5 465 569
6 765 958
30 397
24
0
556 981
27 849
4 000
529 132
5 990 700
7 291 090
31 849
25
0
587 615
29 381
4 000
558 234
6 544 934
7 845 324
33 381
26
0
619 933
30 997
4 000
588 937
7 129 871
8 430 261
34 997
27
0
654 030
32 701
4 000
621 328
7 747 199
9 047 589
36 701
28
0
690 001
34 500
4 000
655 501
8 398 701
9 699 090
38 500
29
0
727 952
36 398
4 000
691 554
9 086 255
10 386 644
40 398
30
0
767 989
38 399
4 000
729 589
9 811 844
11 112 234
42 399
83
Appendix E: PVsyst 5.41 simulation parameters and main results.
84
85
86
Appendix F: Data for investment cost evaluation of PV system.
Year Payment
[SEK]
Prod el
Accumulated profit
[SEK]
Accumulated produced
electricity
1
110900
5 223
-105677
5223
2
0
5 511
-100166
10734
3
0
5 814
-94352
16548
4
0
6 134
-88218
22682
5
0
6 471
-81747
29153
6
0
6 827
-74920
35980
7
0
7 202
-67718
43182
8
0
7 598
-60120
50780
9
0
8 016
-52103
58797
10
0
8 457
-43646
67254
11
0
8 922
-34723
76177
12
0
9 413
-25310
85590
13
0
9 931
-15379
95521
14
0
10 477
-4902
105998
15
0
11 053
6151
117051
16
0
11 661
17812
128712
17
0
12 303
30115
141015
18
0
12 979
43094
153994
19
0
13 693
56787
167687
20
0
14 446
71234
182134
21
0
15 241
86475
197375
22
0
16 079
102554
213454
23
0
16 963
119517
230417
24
0
17 896
137414
248314
25
0
18 881
156294
267194
26
0
19 919
176213
287113
27
0
21 015
197228
308128
28
0
22 171
219399
330299
29
0
23 390
242789
353689
30
0
24 676
267465
378365
87
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