TUTORIAL
EVERYTHING’S
GONE GREEN
Reduce your carbon footprint and tread
lightly on the Earth by running your
studio from solar power. Greg Simmons
lights the way…
Text: Greg Simmons
Climate change… It’s a scary thought,
and one that Western society has abruptly
acknowledged. It’s hard to say what triggered
the sudden shift in attitude, but there can be no
doubt that Al Gore’s Academy Award-winning
documentary, An Inconvenient Truth, had a lot
to do with it: when the former vice-president of
the USA goes campaigning around the world
on behalf of the world, people pay attention.
In the 12 months following its release in May
2006, An Inconvenient Truth did more for the
environmental movement than decades of
warnings from environmentalists and scientists.
It has made even the most stubborn sceptics
accept the reality of climate change, and has put
the environment firmly on the political agenda.
Unfortunately, the problem of climate change
can’t be solved by a handful of politicians
funding a handful of scientists. The
inconvenient truth is that we’re all part of the
problem, and therefore we must all become part
of the solution. How? By changing the way we
consume energy – especially that derived from
fossil fuels. As a sound engineer or recording
musician, a good place to start is by using solar
AT 48
energy to power your audio technology, thereby
making ‘green notes’.
A solar power system suitable for powering
audio technology is shown in Figure 1. It has
five components: a solar panel, a battery, a
charge controller/regulator, an inverter and a
power board.
SOLAR PANEL
The solar panel consists of an array of
photovoltaic cells that convert sunlight into
electrical energy. The output is typically 15V
DC, but can vary from 12 to 17V depending on
the amount of sunlight it is exposed to.
Because sunlight varies throughout the day and
isn’t available at night, we can’t rely on the solar
panel alone to power our equipment. We need
a way to store the electrical energy produced by
the solar panel so it is available when we want it
– the electrical equivalent of making hay while
the sun shines, and storing it in the barn. This is
where the battery comes into the picture…
BATTERY
The battery stores the electrical energy produced
by the solar panel, and therefore must be
rechargeable. There are numerous rechargeable
battery technologies available; the two of interest
here are lead acid and lithium ion. The lead acid
designs offer the highest power per dollar, but
their considerable weight makes them best suited
to fixed installations. Lithium ion designs are far
more expensive but offer very high power per
kilogram, making them unbeatable for laptops,
mobile phones and other portable technologies.
The chosen battery must be designed to have
up to 80% of its energy discharged between
recharges – this is known as a ‘deep cycle’
battery. Car batteries are not suitable for solar
power applications because they are designed for
starting motors, situations that typically cause
only 5% discharge between recharges. (A car
battery won’t last more than a few months if
regularly used in a deep cycle situation.)
The lifespan of a deep cycle battery is affected
by how deeply it is regularly discharged between
recharges: the deeper the discharge, the shorter
its life will be. It is therefore wise to invest in a
battery that can provide all of your powering
needs without being discharged to very low levels.
Figure 1.
A solar-powered
SSL studio
Solar panel(s)
Charge
controller /
regulator
Inverter
Powerboard
with UPS
+12 to +17V DC
+12V DC
240V AC
240V AC
Laptop
Studio A at London’s ‘The Premises’ is an entirely solarpowered recording/mixing studio featuring an SSL
AWS900 console, a ProTools HD2 TDM system running
from a G5 Macintosh, ATC SCM100ASL and Genelec
S30 active studio monitors, a healthy collection of
microphones, and a host of outboard from
API, Neve, Summit Audio, Thermionic
Culture, Lexicon, TLA, Drawmer
and TC Electronic. You
can read about it here:
www.premisesstudios.
com/studio-A.html
Hard Disk
Interface
Monitors
Earth
Rechargeable
‘Deep Cycle’
Battery
As with all things in life, rechargeable batteries
are not 100% efficient. Deep cycle batteries
are typically 90% efficient, which means that
10% of the energy used to recharge the battery
is lost in the recharging process – this must
be considered when choosing solar panels to
recharge the battery.
The charge controller/regulator serves two
purposes. As a charge controller, it ensures the
energy from the solar panel is used to recharge
the battery correctly (a switch or menu item
selects the appropriate battery technology). As a
regulator, it ensures the DC voltage supplied to
the inverter from the battery and/or solar panel
remains constant.
The more expensive charge controller/
regulators include metering to show all input
and output voltages and currents. Apart from
monitoring the overall performance of the
system, this is invaluable for fine-tuning the
position of the solar panel(s) for optimum
conversion of solar energy.
The inverter takes the DC voltage from the
charge controller/regulator and converts it
to the 240V AC required to power our audio
technology.
Most inverters have a single power outlet socket,
so you’ll need a power board if you want to
connect more than one item to the solar power
system. Make sure you choose one with enough
sockets to power all of your equipment, and
allow extra space for any overly-wide AC
adaptors that block access to adjacent sockets.
It is worthwhile writing ‘solar power’ in clearly
visible letters on the power board, not only for
identification purposes but to prevent someone
from inadvertently plugging a heater or iron
into the system and flattening your battery.
A power board with in-built UPS
(Uninterruptible Power Supply) is a smart
investment, because it will provide back-up
power to your equipment in the event that
your battery runs flat and you want to keep
working. A UPS contains a small rechargeable
battery and a simple inverter that only come
into action when there is a loss of input power. It
requires some electrical power to run its internal
monitoring circuitry and keep its battery
charged, but it’s not significant.
Do you need an inverter? If all of your
equipment is capable of operating from +12V
DC (e.g. a location sound rig for film and
television work), you could avoid the expense
and efficiency loss of the inverter and power
your equipment directly from the charge
Lower cost inverters produce an output that is
described as a ‘modified sine wave’, which is
essentially a poorly filtered 50Hz square wave.
These are not recommended for audio work
Solar Regulator
The UPS sounds an alarm to let you know
when it is no longer receiving 240V AC (some
≈
+
+
+
Deep Cycle Battery
POWER BOARD
While inverters add the convenience of mains
power compatibility, there is always a slight loss
of power involved in the process of converting
DC to AC. This loss defines the inverter’s
efficiency, which is typically around 90% (e.g.
10W of power from the battery will produce
9W of power from the inverter). This efficiency
loss must be considered when choosing the most
appropriate battery for the system.
INVERTER
Solar Panel
An important word about electrical safety: the
inverter produces an output voltage of 240V AC,
and therefore requires an earth connection to
maintain electrical safety. This is not something
to be taken lightly – the 240V AC output of a
solar power system can kill you just as easily
as the mains power. So always consult with a
solar power equipment supplier about the most
appropriate earthing method for your situation.
The more expensive inverters produce a ‘true
sine wave’ or ‘pure sine wave’; this is the type
of inverter required for audio work. With less
than 4% total harmonic distortion, the power
supplied by most true sine wave inverters is
cleaner than that supplied by the mains, which
typically has 5% total harmonic distortion.
(When you add to that the audio frequency
tones superimposed on the mains to control
off-peak hot water services and so on [look up
Zellweger/Decabit ‘ripple control protocol’ for
more information], ‘wireless’ home intercom
systems that use the mains wiring as a signal
path, and any other electrical trash picked
up on the journey from the power station to
your house, the mains power itself ought to be
condemned as an audio hazard!)
CHARGE CONTROLLER/REGULATOR
+
controller/regulator. But if you want the
convenience of connecting your equipment
directly to the solar power system as if you were
connecting it to mains power, you’ll need the
inverter.
because the output voltage contains many oddorder harmonics of 50Hz (e.g. 150Hz, 250Hz,
350Hz, 450Hz, etc.) that can bleed through the
power supplies of audio technology and create
a buzz in the signal – especially if you’re using
budget audio technology that isn’t expecting
anything higher than 50Hz from the mains
power and therefore has poor rejection of those
higher frequency harmonics.
A deep cycle battery’s lifespan is also affected by
how it is recharged – it is possible to overcharge
a battery, thereby reducing its lifespan or
destroying it altogether. Each different
battery technology has a preferred method of
recharging to maintain an optimum lifespan
(delivering that preferred method is one of the
roles of the charge controller/regulator).
Inverter
$2000
Powerboard
AT 49
will even send a notification to your PC via
USB), and ought to keep your equipment
running long enough to save your work,
disconnect the power board from the inverter
and connect it to mains power. Conveniently,
this allows all of your equipment to remain
connected to the same power board; changing a
single plug determines whether your equipment
is running from solar or mains power. You
won’t be making green notes when running
from mains power, but it’s reassuring to know
that your commitment to solar power won’t be
compromising your creative flow.
CHOOSING A SYSTEM
The first step in choosing a solar power system
is to calculate the total power that your audio
technology requires. Start by finding out how
much power each individual device consumes,
then add up all the individual values to
determine the total power requirement.
The complete trekking
solar power system
(folding solar panels,
charge controller/battery
pack, and inverter)
recharging the Nagra
V’s internal batteries in
a Nepalese village. Pic:
Rafaelo Porter
The power consumption of each device can be
found in the specifications of the equipment,
and sometimes it’s printed on the back of the
equipment itself. For devices that are powered
by AC adaptors, the power rating is often
printed on the adaptor.
Power is the product of voltage and current, and
is usually rated in ‘Watts’ (abbreviated to ‘W’),
although some devices will specify it as ‘VA’
(Volt Amps) or even simply as a voltage (Volts or
V) and a current (Amps or A). If it is specified
as VA, it can be considered the same as Watts
for this purpose. If it is specified as a separate
voltage and current, multiply the two together
to determine the power in Watts (i.e. Watts =
Volts x Amps). If you’re not sure how to find
this information, ask an electrician or electronics
technician for help.
AN EXAMPLE CALCULATION & SYSTEM
The following example calculates the total
power requirement for a laptop-based system
built around an IBM ThinkPad T43 with a
Seagate Barracuda 3.5 inch external hard drive
(500GB, 7200rpm), an MBox 2 Pro audio
interface, and a pair of Dynaudio BM5A active
nearfield monitors.
Greg Simmons watches
as Dil Gurung and the
horse handler fit the
solar panels onto the
back of a horse. The
battery and charge
controller are in a saddle
pack. Pic: Mikhael
Valeman
Practising what
I’m preaching
I put my first solar power
rig together in November
2006, before venturing out
on a recording expedition
into the Himalaya. I
needed a highly portable
system with folding or
rollable solar panels that
could be hung across the
back of a pack animal (e.g.
a yak, mule or horse) to
take advantage of the high
altitude sunlight while
trekking.
Although I wanted to buy
locally, I could not find
an Australian supplier
who catered for my
needs. Looking off-shore,
I found an excellent
system from a US
company called CTSolar. It
consists of a 32W folding
solar panel, a charge
AT 50
controller/regulator
and a 16A/h battery, all
neatly packaged in blue
rip-stop nylon. Landed
cost was around $850
AUD (including priority
delivery). Because it is
only intended for charging
batteries, a simple 150W
modified sine wave
inverter from Jaycar ($50)
added the finishing touch.
It’s more than enough
to keep the batteries
charged on my recording
equipment. The solar
panels collect the solar
energy during the day’s
trekking, and the charge
controller stores it in
the battery. The stored
energy is transferred to
the recording equipment
overnight, so I start each
day with fully charged
batteries.
When it’s not trekking
with me, the system earns
its keep in my Nepalese
fiancé’s remote village
in the foothills of the
Annapurna ranges. Her
younger brother goes to
school in the morning and
spends the rest of his
daylight hours working in
the fields, so he has to do
his homework by firelight.
My solar power system
gives him electric lighting
to study by, and runs a
portable cassette/radio so
he can enjoy his favourite
Nepali and Hindi pop
songs at the same time.
– Greg Simmons
Laptop: 60W
External hard drive: 10W
Audio interface: 6W
Active monitors: 30W per monitor (two
monitors)
This recording system requires 60W + 10W +
6W + 30W + 30W = 136W of power to operate.
Because this power will be supplied from the
battery via the inverter, we must allow for the
inverter’s efficiency, which is typically 90%. So,
the total power required from the battery equals
136W / 0.9 = 151.11W, which we can safely
round down to 150W.
To assemble a solar power system for this
laptop-based system, we need to know two more
things: how long the system needs to provide
power for between recharges (also known as
the system’s ‘autonomy’), and how many hours
of ‘peak sunlight’ are available for recharging
(peak sunlight is required for the solar panel
Denis Crowdy’s
system for portable
multitrack recording
I’ve done quite a bit of
field recording, and I’ve
always been interested in
getting decent multitrack
recordings rather than
the good old ethnographic
stereo mic standard. My
recording rig is currently
built around an Apple
Macbook (white model)
and the very versatile
Metric Halo 2882 MIO,
which can be powered
from anywhere between
+9V to +30V, provided it
can draw 16 Watts. It can
be powered directly off the
Firewire bus (taking power
from the laptop’s internal
battery) or from a separate
supply.
I decided to put together
a solar power system for
a recording expedition
I had planned to the
Solomon Islands. I pieced
things together from
on-line ideas, and from
calculations suggested
by engineers working at
appropriate shops. The
best response I got was
from energymatters.com.
au. They have a useful
online calculator, and the
people I spoke to didn’t
baulk when I said I was
trying to put together a
laptop-based recording
studio powered by the sun!
My system contains two
to produce its best output.). For this example,
we’ll assume the system needs to provide
power for three hours per day, every day (i.e.
autonomy = one day). And we’ll also assume
a minimum of four hours of peak sunlight
per day for recharging, which is achievable for
most residents of Australia throughout the year
(according to average hours of sunlight statistics
from the Bureau of Meteorology).
The information necessary to assemble the solar
power system is summarised below:
Power: 150W
Autonomy: 3 hours per day
Peak sunlight: 4 hours per day
CHOOSING THE BATTERY
A battery’s ability to provide power is measured
in Amp/hours (A/h); a figure describing the
amount of current it can provide for one hour
before going flat. Amps and hours are inversely
proportional, so doubling the current would
halve the hours and vice versa. Therefore, a
battery rated at 10A/h can provide 10A for
one hour, 20A for half an hour, 5A for two
hours, 1A for 10 hours, or any other realistic
combination of Amps and hours that equals 10
when multiplied together.
For the example above, the battery must provide
150W of power. To determine the appropriate
A/h rating, the first thing we need to know
is the battery’s output voltage – from this we
can calculate the current required (current =
power/voltage). Solar power systems typically
use either 12 or 24V battery systems; for the
purposes of this exercise we’ll use a 12V battery.
To produce 150W from a 12V battery requires a
current of 150 / 12 = 12.5A. A 12V battery that
can supply 12.5A for one hour will therefore be
able to provide 150W for one hour.
Now that we know the current required per
hour, we can multiply it by the number of hours
the system will be used between recharges (i.e.
the autonomy). If the system was going to be
used for three hours per day, every day, between
recharges, then the total A/h requirement of the
battery would be 12.5 x 3 = 37.5A/h.
20W solar panels, a charge
controller/regulator and a
28A/h battery; total cost
was about $800. Powerwise it went well, and we
managed a solid five hours
or so of recording in a day
without any problems. A
slightly larger solar panel
(say, 60W or 80W) with
a bigger battery would
allow some pretty solid
recording time.
It is vital to be organised,
so that when the machine
is on, you are recording,
not fiddling around
setting up patches or
troubleshooting. Setting
up templates in the DAW
application is important
– inputs, monitoring
buses and so on should be
ready to roll as quickly as
possible. The 2882 was
amazing in this respect – it
sounds great and allows an
impossibly flexible array
of routing possibilities. It’s
like having a console in the
bush, but more flexible!
– Denis Crowdy
Regular readers will
remember Denis from
issue 47, where he
spoke of his adventures
recording stringbands
in Papua New Guinea
amidst the fallout from
an active volcano (‘Songs
of the Volcano’). For more
information about his solar
power system, go: www.
motekulo.net/solar.html
This figure assumes the battery is going to be
fully discharged between charges, which is not
healthy for the battery! So we have to factor
in the depth of discharging. If we want the
battery to have no more than 80% of its energy
discharged between charges, its A/h rating will
be 37.5 / 0.8 = 46.88A/h, which we’ll round up
to 47A/h.
In other words, a 12V battery rated at 47A/h
can provide 150W of power for three hours, and
still have 20% of its charge remaining. This is
the minimum battery capacity required to run
the system in the example for three hours. If
the budget allows it, a larger battery is a better
choice because it requires less discharge depth
and will therefore have a longer life. It would
also allow greater autonomy in the event of an
overcast or rainy day with less than sufficient
sunlight.
CHOOSING SOLAR PANELS
The solar panel’s job is to replace the power
taken from the battery. To determine the
appropriate solar panel, we need to know a) how
much power has been taken from the battery, b)
how many hours of peak sunlight we can expect
per day for recharging, and c) the battery’s
efficiency.
Because the voltage and current produced by a
solar panel varies with the amount of sunlight,
we cannot use Amp/hour figures reliably.
Instead, we use Watt/hours (W/h).
In the example above, the audio technology
drew 150W from the battery for three hours,
making a total of 150 x 3 = 450W/h. We chose
a conservative figure of four hours per day of
peak sunlight, which means the solar panel
must produce 450/4 = 112.5W per hour. In
other words, a solar panel rated at 112.5W
would recharge the battery after four hours
of peak sunlight – but only if the battery was
100% efficient, which it is not. Factoring in
a typical battery efficiency of 90% means the
solar panel must produce 112.5/0.9 = 125W per
hour. A 125W solar panel would recharge a 90%
efficient battery with 450W after four hours of
peak sunlight. A more expensive 250W panel
AT 51
“Taking advantage of on-line
purchasing discounts from
local suppliers, a suitable
system can be purchased for
approximately $2000 AUD.”
12 or 24 Volts?
As calculated in the
example, a 12V battery
must provide 12.5A
to the inverter. That’s
a significantly high
current and will require
heavy-duty wiring between
the battery, charge
controller/regulator and
the inverter. If a 24V
battery and inverter were
chosen, this current would
halve. Here’s the maths:
to produce 150W from
a 24V battery requires
a current of 150 / 24 =
6.25A. So, a 24V battery
that can supply 6.25A for
one hour will be able to
provide 150W for one hour.
Because the system will
be used for three hours
per day, every day, the
total A/h requirement for
a 24V battery is 6.25 x
3 = 18.75A/h. Factoring
in a maximum discharge
depth of 80% means the
total A/h requirement of
the 24V battery would
be 18.75 / 0.8 = 23.4A/h,
which we’ll round up to
25A/h.
For smaller systems, like
the one in this example,
12V technology is usually
the most cost-effective.
With larger systems, 24V
technology may prove to
be more cost-effective.
would recharge the battery after just two hours,
while a cheaper 62.5W panel would require
eight hours.
Solar panels are available in many different sizes
and power ratings. Sometimes it is not possible
to get a single solar panel with sufficient output
power. In this case, two or more solar panels can
be connected together in parallel. The example
above required a solar panel rated at 125W.
A single 125W solar panel would do the job
nicely, but other combinations are possible. Two
60W solar panels wired in parallel will produce
120W. Likewise, four 30W solar panels wired in
parallel will also produce 120W. (Both of these
examples represent a shortfall of 5W per hour,
or a total of 20W during the four-hour peak
sunlight recharging period. This is acceptable
because the panels will almost certainly be
exposed to more than four hours of sunlight per
day, allowing them to make up the difference
– a 120W panel will produce the extra 20W in
10 minutes of additional peak sunlight.)
The ability to combine solar panels has another
benefit if the budget is tight. For the example
above, it may be possible to start with a single
60W solar panel and add a second solar panel
when the budget permits. The downside is
that a 60W solar panel will take longer to
recharge the battery. If, however, you lived in
an area that got considerably more than four
hours of peak sunlight per day, a 60W solar
panel might be sufficient. Likewise, if the
audio technology was only used on alternating
days (e.g. Monday, Wednesday, Friday, etc.), a
60W solar panel would have plenty of time to
recharge the battery. If the audio technology was
only used one day per week (e.g. Saturdays), an
inexpensive 30W solar panel would have plenty
of time to recharge the system during the week.
One final note: The effectiveness of a solar
panel is affected by its physical positioning in
relation to the movement of the sun across the
sky. Careful positioning is required to maximise
the output power. This is where the voltage
and current indicators provided on the more
expensive charge controller/regulators come in
handy – by monitoring the output voltage of
the solar panels, it’s possible to fine-tune their
position for optimum output power.
CHOOSING THE OTHER PARTS…
Now that we know the battery and solar panel
requirements, we must consider the devices
that interface them together and to the audio
technology they are powering: the charge
controller, the regulator, the inverter and the
UPS power board.
The charge controller must be able to withstand
the highest current the solar panel is capable of
producing, which is known as its ‘short circuit
current’. Incorporating a safety factor of 1.5
ensures the charge controller is never pushed to
its maximum capability. So, if the solar panel’s
short circuit current is 5A, a charge controller/
regulator rated at 5 x 1.5 = 7.5A would be a
good choice. (Note that if you are using two or
more solar panels in parallel, you must add the
short circuit currents together to arrive at a total,
AT 52
which the safety factor is then applied to.)
The regulator must be able to pass current
from the battery to the inverter without being
damaged from overheating. The system used in
the example above drew a total of 12.5A from
the battery – the regulator must be capable of
passing this current. Again, a safety factor of 1.5
is worth considering, suggesting a minimum
of 18.75A, which we’ll round up to 20A to suit
commercially available products. Likewise, the
inverter must be able to accept this current from
the regulator and deliver 136W of AC power to
the audio technology – a 150W inverter would
be the minimum choice for this purpose, but a
200W inverter would be wiser.
The wiring used to interconnect all the
components must also be considered. Solar
power systems are low voltage systems, and
that means they need much higher currents
to produce power. The 12V system described
here needs 12.5A of current to produce 150W
of power. In comparison, a 240V AC system
needs only 0.416A to produce the same power.
Passing 12.5A of direct current (DC) through a
wire safely and efficiently requires heavy-duty
wiring – even the power leads used for domestic
appliances are insufficient for this application.
This is why the wiring used for car batteries
is so thick; a larger diameter wire has less
resistance, and is therefore capable of passing
a higher current with greater efficiency and
safety. If the wire is too thin and has too much
resistance, it will create a voltage drop (resulting
in a loss of power) and may even overheat and
cause an electrical fire. The companies that
provide solar power equipment can recommend
suitable wiring.
The UPS power board must provide sufficient
back-up power to keep the audio technology
running for about 10 minutes; more than long
enough to save your work and either shutdown
or change over to mains power. For the example
given here, the UPS should be able to provide
136W of power for 10 minutes. Most UPS
power boards come with a chart showing how
long they can power different systems.
A PRACTICAL SYSTEM
The audio technology used for this example is
typical of the smaller systems used in project
studios. Based on the calculations above, the
minimum requirements to power this system
are:
1 x 125W solar panel
1 x 47A/h deep cycle battery
1 x 20A charge controller/regulator
1 x 150W inverter
1 x UPS power board
Taking advantage of on-line purchasing
discounts from local suppliers, a suitable system
can be purchased for approximately $2000.
This cost may seem high, but remember that
the calculations used very conservative figures,
erring on the side of caution, to propose a solar
power system that should reliably provide three
hours of power per day, every day – along with
UPS back-up for easy transfer to mains power
Horse Power: Marc Peckham’s self-sufficient
setup includes four solar panels, 12 batteries
within the float and a wind turbine to top
things up during the breezy evenings. His
container-based studio packs a collection of
hip hop favourites such as an Akai MPC3000
as well as a few novelties, including a Levy’s
Sound Studios Pultec EQ copy that Jimi
Hendrix recorded his guitar through for Are
You Experienced? (the actual unit).
ANYONE CAN MAN
A hip hop studio in a shipping container… powered by solar
panels mounted on a horse float?! Read on.
The Aussie hip hop community has little in common with its
US counterpart. Bling and a ‘get rich or die trying’ ethos are
replaced by groups with barely a dollar to their name and a
heart for the fringe. It’s this ground that Welsh-born Marc
Peckham, aka Monkeymarc, treads loud and clear. On the
spend of mostly private funding, Peckham travels to the The
Western Desert and Kimberley region for six months of the
year to help Aboriginal community elders impart knowledge to
the younger generations in a form relevant to the times. Along
the way he also documents field recordings of their traditional
songs, and when he’s not in The Kimberley, Peckham is home in
Abbotsford remixing the likes of The Herd and making music
in his band, Combat Wombat.
Global warming might be the issue du jour, but back since
1998 Marc’s been considering how he can make a difference.
The impetus behind his solar experimentation was to prove
that ‘alternative’ living and a ‘zero impact’ isn’t some magical
proposition out of reach of the layman. It’s something he has
learnt from scratch, and has worked up from a four-wheel
bicycle contraption used to power parties to the solar
panelled horse float that powers his Abbotsford studio today.
The studio itself is housed in an old refrigerated shipping
container, and he’s been given special dispensation by mother
superior to park it in the grounds of the Abbotsford Convent.
Furnished with wood from an old indoor netball court, and
treated with Rockwool and foam baffles, the aluminium
container came out a treat. The equipment list required to
power the container and its gear involves 12 x 24V batteries,
four solar panels, a 240V inverter and a small wind generator
to top up the power overnight when the sun goes down. The
setup comfortably powers his studio for eight to 10 hours at a
time, with a break on weekends to let the batteries return to
their maximum. And if that’s not enough, Peckham estimates
he could power a 3000W PA for eight hours with his solar
trailer. Not a bad effort. He is looking to expand his system
with another four solar panels to get through the Melbourne
Winter, an understandable notion given the grey clouds on the
day of the interview.
And the reasoning behind the horse float? Well, a shipping
container doesn’t afford much space, and a couch full of
batteries isn’t exactly comfortable. Plus, there’s the added
benefit of being able to pull around power, and if the Convent
decides Combat Wombat should move on, then a simple car
hookup and Peckham can follow the container wherever it
may go. – Mark Davie
if necessary. We must also bear in mind that
it’s an ambitious system because it attempts
to power the studio monitors, which add
significantly to the total power consumption
(60W of the total 136W, or 44%), and therefore
to the cost. It would be possible to start with a
smaller system that powered everything except
the studio monitors, for an initial investment of
approximately $1000, and add more solar panels
and/or batteries as funds permit to gradually
migrate your entire studio to solar power. (As
with solar panels, batteries can be connected
together in parallel to increase the total current
capability.)
Connecting with
the earth
Going green may be
‘earthier’ than you think:
the inverter used in the
solar power system
described here produces
an output voltage of 240V
AC, and therefore requires
an earth connection to
maintain electrical safety.
This is not something
AT 54
to be taken lightly – the
240V AC output of a solar
power system can kill you
just as easily as the mains
power. So always consult
your solar equipment
supplier about the most
appropriate earthing
method for your situation.
It is also important to remember that the solar
power system described here is powering a
laptop computer with a consumption of 60W.
This figure includes the power required to
charge its internal battery, in which case it is
simply transferring electrical energy from one
place to another. Once it is fully charged, the
laptop could be disconnected from the solar
power system and powered from its internal
battery, thereby extending the power capability
considerably beyond three hours.
LET THE SUNSHINE IN!
Australia is blessed with an abundance of
solar energy, and an abundance of solar power
technology suppliers. Most have helpful staff
and informative websites; some even include
on-line calculators to help you choose the most
appropriate equipment. Always discuss your
solar power system with a supplier to ensure it
will be correctly rated and properly earthed.
For more information, log on to
AudioTechnology’s website and download the
resources to accompany this article (follow the
links). These include Excel spreadsheets with
lists of power requirements for common items of
studio equipment, calculators to help determine
the best solar power system for your needs,
recommended systems, and links to local solar
power technology suppliers.
By converting to solar power, you’ll be joining a
growing list of artists around the world who are
producing green notes. So what are you waiting
for? Go green, go clean, and become part of the
solution!