Specifications

AT 48
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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
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.
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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…
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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.
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
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