All of the Solar Utilities Network's web pages are built and maintained
on a solar-powered computer. Why? Because, just between us
(don't let them hear) we don't trust our beloved local
electrical monopoly to supply us with an unbroken stream of within-spec
and NEITHER SHOULD YOU.
We use an industrial strength uninterruptible power supply because
out here at the end of the grid, power outages are so common that
we would lose work a couple of dozen times a year. In the last
two years, we would have lost two weeks of work to power outages. Our
power company is a little more candid than most, and they admit that
the situation will get worse, because they have had to defer maintenance
and cut crews to keep between the rock of rising fuel costs and the
hard place of the state public utilities commission.
We are not alone. Prudent engineers almost always isolate mission
critical process controllers and communications gear from the
grid. In old systems where this isolation is not in effect — take
the air traffic control system, please — down-time
for the control equipment means that all those unfinished processes
are just floating around in mid-air. The FAA is aware of the problem,
and is installing stand-alone equipment much like that used by
us here at SUN.
On a good day, sun shines on our eight photovoltaic modules, and
is metered in to our 400-amp-hour nickel-cadmium battery bank.
On cloudy days when the grid is working properly, our solar-electron
harvest is often supplemented when our inverter's built-in charger kicks in.
We estimate that over the course of the year, about 25% of our
electrons actually come from the grid. Direct current electricity
from the batteries is converted by the inverter into the kind
of electricity our computer equipment wants to see.
Days of Autonomy
When the power fails, our battery bank stores enough energy to
keep our carefully designed home's energy saving equipment running
for about four days without resorting to heroic measures like
a fossil-fueled generator — at Solarnet, we would never
do that. We give up our big computer during times like those in favor
of lights, running water, refrigeration, and tunes. We consider
such outages to be natural holidays.
Would a system like ours make sense for you? If you want to be
absolutely sure your power will not fail, you certainly
need to do something. We like our solution because it will work
without surprises for a couple of decades. If you are prepared
to wait for the power to come back on, you only need enough uninterruptible
energy to make an orderly exit from your mission critical processes.
If you are as intrigued as we are by energy, and want to make
it a hobby, this is a good serious project to undertake. Does
it make economic sense compared to the grid? That depends on how
valuable you consider your work.
In the my new book, the revised and updated The New Independent Home, we document the design and construction of a major off-the-grid homestead being built by one of my students
in the wilds of cloudy Washington. To bring conventional power to
the site, a spectacular mountainside far from the nearest power pole,
would have cost at least $22,000, which would buy the privilege of paying a
monthly utility bill. The solar-powered system which will cost much less
initially, never have a monthly bill, and will still provide clean,
adequate power to the residents.