Die Energie ist da Präsentation der juwi-Gruppe
Design Requirements for a successful Solar
Kai Ilham Klingenhagen Business Development APAC∙ juwi Group
1. juwi at a Glance
2. Why a good Design?
3. Design Steps in different Project Stages
Developer perspective, EPC perspective
4. Design Basics
5. Simulation Softwares
6. Q & A
juwi at a Glance
Founded in 1996 by Fred Jung and Matthias
Willenbacher (juwi), pioneers for renewable
energies with agricultural roots
juwi AG is an owner-managed group of
companies and not listed on the stock exchange
Total capacity
Around 3,000 megawatt (approx. 2,300 systems)
Annual energy output
Approx. 5.5 billion kilowatt-hours, corresponds to
the annual power demand of around 1.5 million
Investment volume (since 1996)
Approx. 5.9 billion Euro
Employees & turnover
> 1,500 employees (worldwide)
Approx. 1.0 billion Euro in 2012
International Offices, Project Locations and New Markets
Bulgaria, Czech Republic, France,
Germany, Great Britain, Greece, Italy,
Poland, South Africa, United Arab
Chile, Costa Rica, USA/Canada,
India, Malaysia, Singapore, Thailand,
Japan, Philippines
OUR PASSION - All about the Project
Consulting &
Financing &
Operation &
3,000 MW Wind & Solar projects completed
In more than 20 countries of which 5 are in Asia Pacific
Asia Pacific, more than 150 MWp completed
Thailand 61 MWp│Japan 5 x 1 MWp, Rajasthan 26.4 MWp, Gujarat 24 MWp│Malaysia 10 MWp
Japan 9 projects completed to date
Higo Otsu 1 MWp, Kyushu (Japan)│Bear 2, Rooftop, 1 MWp, completed Bear 1, Freefield, 1 MWp
Wind Power 2013: ~350 MW plus paper deals
Large Turbines & High Towers
Costa Rica, Germany, USA, Poland│7.5 MW turbines & up to 145 m juwi ATS hybrid towers
juwi Asia Pacific 2014
>120 staff (Singapore, India, Japan, Thailand, Malaysia, Philippines)
Regional Headquarter in Singapore
- India: 75 MW completed since 2011
- Thailand: 61 MWp
- Malaysia: 10 MW Carport
- Japan: 9 projects with more than 10 MW completed
+ several MWp under construction
>400 MW pipeline
- Philippines: several MW projects in construction start
- Taiwan: multiple rooftops since 2012
Why a good Design?
Why is a good Design the key for a successful project?
Why a good Design?
- A.: to avoid failure or lower generation
Shading objectives
Why a good Design?
- A.: to avoid failure accidents and loss or breakage
Wind Load and selection of Materials
Why a good Design?
- A.: to avoid burning cables or inverters
Design in Different Project Stages
Project Stages from early Development
Consulting &
Financing &
Scouting for land
Land identification & Selection
Preliminary title search
Signature of MOU with land owner
Preliminary Utility response
Local (PPA) application*
Topographic Survey
Irradiation review
Operation &
Design Steps
Input Information
Yield (Irradiation) analysis
Grid capacity analysis
Grid interconnection requirements
Flood study
Soil testing and preliminary foundation
Selection of most optimal module angle
Project Stages up to construction
Consulting &
Financing &
Component Preference
Useful Area
Environmental Disturbance
Grid Impact Study
Flood Studies
Operation &
Design Steps
Input Information
Layout incl. Component evaluation
Shading Analysis (Near, Horizontal)
Inverter calculation
String Configuration
Yield Analysis
Detail Design stage calculation
4. Basic Design
4.1. Yield Analysis
Available Irradiation
To be evaluated after site selection, or in
discussion with the available sites
Available irradiation on several free
sources in the internet, plus professional
commercial databases
Free sources can provide a first glim of
expected Energy yield
Available in kwh/m²
4.1. Yield Analysis
Available Irradiation
Considering of micro climate necessary
The diffuse radiation and the direct radiation are the global radiation
The intensity of the solar irradiance (W/m2) depends on local/global
weather condition.
Weather, Environmental conditions and ground reflection (albedo)
having an direct effect on the diffuse fraction
4.2. Grid Capacity Analysis
Grid capacity needs to be discussed with local Utility or Grid Authority
In Thailand to be discussed with PEA and MEA
In certain Regions in Thailand already problematic to connect Solar Power to the Grid
Weakest points are the Substations and the overload in the specific grid, if solar power
would be connected, the request for regulation of the solar power plant is a must, which is a
loss for the investment
4.3. Grid interconnection requirements
 Requirements for the interconnections in Thailand are :
- Switchgear
• Circuit breaker (Vacuum or SF6 insulated) with 25kA (Isc)
• Current transformer (Accuracy class : 5P20 or above)
• Power Quality Meter (Profile Recording “RMS average, Min & Max
every 10 mins based on Std. EN 50160)
• Others (Based on IEC standard or suppler list)
Pic. Source: Schneider Electric
4.3. Grid interconnection requirements
 Requirements for the interconnections in Thailand are :
- Grid Harmonization
• Don’t allow VSPP to apply Automatic Reclosing Scheme
• Synchronization done at Interconnection CB
• Anti-Islanding shall be applied
• Protective relay shall be coordinated with PEA’s system
• Voltage level (± 5% for alarm , ± 10% for emergency)
• Power Factor (0.9 lag thru 0.9 lead while injecting power > 10% Inverter capacity)
• Power Frequency 50 Hz (49.5-50.5 Hz for alarm , 48.00-51.00 Hz for emergency)
• Reverse DC current to grid (< 0.5% rated current of inverter)
• Power quality meter shall be provided if inverter capacity is above 250 kW.
• Etc. (Voltage Fluctuation, Harmonic Distortion)
4.3. Grid interconnection requirements
 Requirements for the interconnections in Thailand are :
- Grid Protection for VSPP with 3 phase inverter connected to 22kV system
Under Voltage relay / Over Voltage relay (27/59)
Instantaneous O/C relay / IDMT O/C relay (50/51 & 50N/51N)
Frequency relay (81)
Synchronizing relay (25)
Anti-islanding protection
Remote control to disconnect the plant from grid shall be provided
(if Total inverter capacity > 2MW or Transformer capacity >2MVA)
4.4. Flood Study
 A Flood study is crucial for the investment and can be the key changing point of a project to
be feasible or not feasible
 Should be provided from local experts which includes the evaluation of local information, as
well available Meteorological data and topographical maps
 The recommendation needs to be integrated in the civil design (drain design etc.)
4.5. Soil Testing and preliminary foundation
 Soil testing is done to evaluate the method of foundation
 Test’s should include the following test’s as a min:
 Field Investigation (Boring, Soil Resistivity, Seismic Down Hole)
 Laboratory Test (Atterberg Limits, Chemical Analysis, Particle Size
 Pullout Test
4.6. Module tilt angle
 Elevation of the Sun to the surface varies within 365 days of the year. The closer to the
Ecuador, the lesser is the variation.
Module Angle = 10º
Location Jakarta
Module Angle = 10º
Location Bangkok
4.6. Module tilt angle
 Choosing the Module declination for the
highest annual energy output
 Easy Rules to Remember:
 The higher the Latitude the greater the
Module Angle
 Min. Angle of 10º for self cleaning purpose a
 In Thailand most optimum between 10 and
20 degree
4.6. Module tilt angle
 Azimuth is the direction facing the Sun.
 Located in the Northern Hemisphere we choose 0º (means facing South)
 Located in the Southern Hemisphere we choose 180º (means facing North)
 Only on roof top installation, we would work with different Azimuth’s
4.7. System Layout
 Shape of the available land area
 Max AC Power which is required
 Row to Row distance
 Area’s of concerns
Outside shading objects
Inside Pont's and creeks
Possible Flood preventions
4.7. System Layout
 Choosing the most economical and technical suitable solution
 Monocrystalline, Polycrystalline, Thin film technology
 Must haves of Modules:
 IEC tested 61215 and 61730
 CE certified
 PID test
 Positive power tolerance
 3rd Party Performance test
 Independence Factory test
 Salt Water Resistance Test
 25 years linear performance warranty
 Min. Temperature Coefficient
 Reference Projects
4.7. System Layout
Module A efficiency xx 225 Mono:
ηModule = 225 W / Module Area= 13.4%
Module B, efficiency 225Wp Mono:
ηModule = 225W / Module Area= 13.7%
Cell efficiency 225 Mono:
ηModule =3.75W/ Cell Area = 15.4%
Module A performed better:
- Module A, 225 Mono Yield: 1124.4kWh/kWp
- Module B, 225 Mono Yield: 1112.6kWh/kWp
4.7 System Layout
Mounting Structure
 The mounting structure (MS) needs to be designed according to
 Required standards (มยผ 1311-50 มาตรฐานการคํานวณแรงลมและการตอบสนองของอาคาร) and
 Wind Loads ( In Thailand reference range from 25 m/s to 29 m/s and TF =1.0 to 1.2)
 Min. Galvanization thickness as required (harsh environmental conditions near the sea for e.g.
requires a min of 80 µm galvanization thickness)
 MS area available in Aluminum and Galvanized steel
 Galvanized Steel more cost effective
 Different foundation available (depends on soil)
 Min 10 years workmen ship guarantee
 Wind loads of up to 250 km/h feasible
4.7 System Layout
Mounting Structure
 Part of the MS is the selection of the correct foundation which depends on the soil condition
 Important information for the design stage is length and foundation
 One key for the right selection is cohesion and available machines/ tools
4.8. Shading Analysis
Horizontal shading
4.8. Shading Analysis
Near shading
 Location: Freiburg, southern Germany (48 °N)
 We want that no shading occurs on noon at
the 21st of December (shortest day)
 What angle does the sun have with the
horizon on the 21st of December? (23.5°)
90°- latitude-declination= sun angle
90° - 48° - 23.5° = 18.5°
 What is the minimum distance x to guarantee
that there is no shading on noon?
l = 1.67m
 X = l * (cos β + sin β / tan 18.5°)
 In general it is always a compromise:
Software tools use optimize factors
4.8. Shading Analysis
 Advance shading analysis with
Simulation software possible as:
 String shading with the effect from row
to row
 Punctual shading
 Horizontal shading
 In Thailand the most efficient row to row
should be around 2.5m
! Target: No shading on the day with lowest Sun evaluation at 12pm.
4.9. Inverter Calculation
Two possible inverter concepts are suitable for Solar Systems:
String Inverter
+ Omission of the PV String combiner/junction Box
+ Up to 1 MWp more cost efficient and if no Service
is available
+ Reduction of the module DC cabling to series
+ Need less extra space
+ faster to repair or to exchange
Central Inverter
+ More cost efficient from >800 kWp
+ less additional mounting structure costs
+ less cabeling costs
4.9. Inverter Calculation
Inverters with Transformers
Transformer less Inverters
Does not need a neutral wire
HF-Technology is smaller and lighter  close to
transformer-less devices
Less efficient compared to transformer less inverters
Light weight
More efficient
Inverters with single MPPT
Inverters with multi MPPT (Multi
String Inverter)
Inputs internally wired parallel
Lower cost
Requires: identical modules, string-lengths, orientation,
shading, roof pitch
Independent optimization of strings with
different modules, string-lengths,
orientation, shading, roof pitches
More expensive
Optional internal parallel wiring
(depending on inverter)
4.9. Inverter Calculation
 High efficiency can only be achieved with high MPP voltage
 Maximize string length (limitation: Observe Open-Circuit voltage at lowest temperature
in the region or use standard -10oC)
 Avoid MPP Voltages below 200V (e.g. Sunny Tripower have in built electronic String
fuses which will only be activated for MPP voltage above 188V)
 Avoid shading as much as possible
 If shading exists, limit shading to one string or to one MPPT tracker (in case of using
multi string inverters)
4.9. Inverter Calculation
Working Areas of PV Generator and Inverter
 The working areas of Inverter and PV generator
array are not congruent
 Sizing of System is vital for effective and efficient
plant design
4.9. Inverter Calculation
Inverter and Plant Design
Design Criteria - Scenarios
Scenario 1: Low MPP Voltage
 The PV generator has its MPP (maximum Power Point) below the Minimum Input Voltage of
The Inverter remains in
operation and feeds the
power of the PV generator
at the Minimum input
This can be avoided by
sizing the PV array at high
MPP Voltage range of
4.9. Inverter Calculation
Inverter and Plant Design
Design Criteria - Scenarios
Scenario 2: Large Open Circuit Voltage
 The PV generator has an open circuit voltage that is higher than the maximum Input
Voltage of Inverter
Depending on intensity of
Overvoltage and module
temperature, the inverter
may be damaged.
This can be avoided by
sizing the PV array below
the Maximum Input voltage
of Inverter
4.9. Inverter Calculation
Inverter and Plant Design
Design Criteria - Scenarios
Scenario 3: Current/Output Limitation
 The PV generator could deliver higher power than the maximum power input of the inverter
The Inverter remains in
operation and feeds its
maximum power on the grid
Having a nominal Power
ratio between PV Generator
and Inverter is important.
The excess power
generated by PV will be lost
if the Inverter is largely
4.9. Inverter Calculation
Inverter and Plant Design
Energy Utilization
For example for an
undersized system
with Power ratio of 0.7,
the energy utilization
factor will be 3-4%
lower than the system
with unity power ratio
4.9. Inverter Calculation
Inverter and Plant Design
Nominal Power Ratio Inverter – PV Array
 For a well designed PV Plant, the power of the Inverter needs to match the power of the
connected PV array
 The Nominal power ratio is the ratio of the power of the Inverter to the power of the connected
PV Array
Nominal PV Ratio = Maximum Input Power of the Inverter
Nominal Power of PV Array at STC*
*STC: Standard test Conditions
4.9. Inverter Calculation
Inverter and Plant Design, Example
Inverter Selection eg. SMC10000TL
Modules: SolarWorld SW 240 Poly
Required Plant Power: Approx. 10 kWp
String sizing
How to decide the optimum number of modules per String?
• Note down the temperature coefficient of the Modules SW240 Poly
Note down the MPPT voltage range, Maximum Voltage Range from the datasheet of
the SMC10000TL
4.9. Inverter Calculation
Inverter and Plant Design
• Note the maximum and minimum Ambient temperature reached at the site of installation
For Minimum temperature, Use -10oC
The Nominal Power ratio should not be lower than 90%, in certain case it is OK to max 80%
Tcell.eff = Tamb.temp + 25
Minimum Voltage of Module
Minimum Voltage occurs at maximum Ambient temperature
Module MPP Voltage = 30.2 V
Voltage coefficient = -0.37%/C
Vmpp_min = Vmpp_STC + (ϒv x (Tcell.eff - TSTC)* Vmpp_STC
Vmpp_min = 30.2+ (-0.0037x (70 - 25)* 30.2 .(Assume Tamb.temp = 45)
Vmpp_min = 25.1717 V
4.9. Inverter Calculation
Inverter and Plant Design
Maximum Voltage of Module
Maximum Voltage occurs at minimum Ambient temperature
Module Open Circuit Voltage = 37.2 V
Voltage coefficient = -0.37%/C
Voc_max= Voc_STC + (ϒv x (Tcell.eff - TSTC)* Voc_STC
Voc_max = 37.2+ (-0.0037x (-10 - 25)* 37.2 .(Assume Tamb.temp = -10)
Voc_max = 42.01 V
Nmin Per String =
𝑉𝑖𝑛𝑣 𝑚𝑖𝑛
Nmin Per String =
𝑉𝑚𝑝𝑝 𝑚𝑖𝑛
= 13.9
𝑉𝑖𝑛𝑣 𝑚𝑎𝑥
Nmax Per String =
𝑉𝑜𝑐 𝑚𝑎𝑥
Nmax Per String =
= 16.65
Therefore, Can place between 14-16 modules in a string
4.9. Inverter Calculation
Inverter and Plant Design
12-14 ModulesUOC
Modules Temperature
To many
14-16 Modules
17 Modules ++
+70°C -10°C
500 V
350 V
+70°C -10°C
+70°C -10°C
4.9. Inverter Calculation
Inverter and Plant Design
Specific Energy Yield: is expressed in kWh per kWp and is calculated as
Specific Yield :
System Energy output
Rated output Power of System
If the performance of systems in different regions need to be compared, shading losses need
to be eliminated from calculation for accurate comparison
Performance Ratio: is used to assess the installation quality.
The Performance Ratio provides a normalized basis so comparison of different types and
sizes of PV systems can be undertaken.
Performance Ratio:
System Energy output
Ideal Energy Output
Ideal Energy Output = Rated output Power of System x Insolation on Panel
4.9. Inverter Calculation
Inverter and Plant Design
Assuming 15 Modules in a string
Rated String Power
Therefore, number of strings required
Maximum String Current
Total Current Input to Inverter with 3 strings
Max Input Current limit of Inverter
= 3.6kWp
= 3 x 3.6kWp = 10.8 kWp
= 8.44 A
= 25.32 A OK
= 31 A
Nominal Power Ratio
= 95% OK
If using 16 Modules in String,
3 Strings per Inverter, Power
Nominal Power Ratio
Use 11kWp Inverter
= 11.52kWp
= 89% NOT OK (ok in regions with
low irradiation and low specific yield)
4.9. Inverter Calculation
DC AC Ratio
A high DC/AC Ratio of 120% (which means more DC Power than AC power) are more cost
Keep in mind: High DC/AC ratio, means:
 Higher losses
 Operating and max level Inverter operating Level
It is advisable to check the warranty conditions with Suppliers before going for the higher
DC/AC Ratio
4.10. String configuration
 String Configuration is based on the operating window and Module requirements.
 This is part of the Inverter sizing as well part of the preliminary wiring plan
4.10. String configuration
Electrical Design LV
4.11. Losses
Major losses occur due to:
Module losses (high Temperature, through
shading, irradiance level, array Soiling,
quality loss)
Inverter Losses (temperature, Module
mismatching, voltage treshold)
Cable losses (in total not more than 1.5%)
Transformer operating losses
4.12. Yield Analysis
Necessary Input data
 Site Info
 Metrological data
 Irradiation, Sunshine hours
 Temperature
 PV System info
 Components
 Geographic Position
 PV array characteristic
 Climate reference
4.10. Detail Design Steps
Detail Design Steps before construction starts and include in general:
Final Module Layout
Cable Wiring, Cable Routing
Single Line Diagram and Details
Details ( Grounding, Combiner Box, Inverter, Main Station, Fence, Roads, etc…..)
Civil Plans
Security Concepts
Technical Calculation (AC cable, DC cable, Inverter Sizing, Road Work installation, etc..)
Technical Specification
4. Simulation Software
Simulation Software
- Overview
Different Software's available from:
 Free supplier:
 free but limited to the Manufacturer specifications
 Best source from Inverter and Module Manufacturers
(SMA, PowerOne, etc)
 Professional Software:
 Use of customer metrological data or generated data as
 Optimized Module Angle and Azimuth selection
 Shading simulation
 Easy String configuration
 Provides a nice print out useable for Proposal and
This is how a plant shall look like…
…in Thailand, India
… or anywhere in Asia Pacific
Thank You Very Much for Your
Kai Klingenhagen
Business Development ASIA Pacific,
Temp. Country Manager juwi Philippines Inc.
juwi Renewable Energies Private Limited
152 Beach Road, # 21-07 Gateway East,
Singapore 189721
Mob. +65 9199 0395
Fax. +49. (0)6732. 96 57-8541
[email protected]
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