| How Can I Actually Use Solar
Cells In My Typical Suburban Home?
|
Solar Cells
Solar or photovoltaic cells
are kind of the ultimate
gadget. You put a solar cell or a panel of solar
cells in sunlight
and it generates electricity--keeps doing it until the sun goes
down. When
the sun comes back up the cell starts generating electricity
again. Most
solar
cells last at least twenty years, probably a lot longer than
that.
They just keep generating power without causing any
pollution. Solar cells
have been "the energy source of the future" for probably thirty years
now, though to be fair the solar cell industry has been growing rapidly
as cost
of production has gone down.
I've always been fascinated
by the potential of solar cells. To be honest I haven't found
many practical
uses for them, but I'm still fascinated.
What
have the obstacles to widespread use of solar power been? Historically
there have been three factors that make using solar power difficult for
the
average person.
- Cost:
When they first started becoming practical, solar cells were expensive
enough that they could only be economically competitive where there
were essentially no competing power sources. Solar cells were
used in extremely remote locations like mountaintops and outer
space. Costs gradually came down and made solar cells
practical for more applications. By the time of the energy
crisis of the 70's, solar cell electricity could be 'only' 10 to 15
times as expensive as typical utility-generated electricity over the
lifetime of the solar installation in areas with a lot of
sunlight. Though that sounds high, solar cell electricity
generation was actually competitive in some situations. If
the choices were to run new power lines for several miles or to use
solar cells, solar cells were often economically reasonable even at the
price levels of the 1970s.
Solar cell costs have been slowly drifting down, getting closer and
closer to the cost of utility generated electricity. It is
possible, though not easy and not inexpensive, to power an average
suburban house using solar cells.
- Compatibility:
Solar cells and the electricity they generate don't fit naturally or
easily into our houses. Solar cells generate direct
current (DC), the kind of power that is produced by a car
battery. Our houses and most of the appliances in them run on
alternating current (AC). You
can't simply plug a household appliance into a solar panel and expect
it to work. In a typical household solar electrical system,
the electricity from the solar cells is fed into a bank of
batteries. As the electricity is needed, it is then fed
through a device called an inverter, which changes
it from DC to AC. That allows it to be used in household
appliances. Solar electrical power for a home requires a
large up-front investment, both because of the cost of the solar panels
and because of the cost of the inverter and bank of
batteries. It doesn't make a lot of sense economically to buy
small amounts of solar panels because you still have to buy the balance
of the system--the inverter, batteries, etc--before you can use most of
your system.
Again, the solar industry is very aware of that problem, and is working
on various solutions.
- The
diffuse nature of the power: A reasonably efficient solar
panel will generate 120 watts per square meter. On a good day
it might generate around 600 watt/hours of power. What does that mean
in plain English? If you want to run three 60 watt light
bulbs an average of 3 hours per night, that will take nearly all of the
power that a solar panel a little over a yard square will generate on a
perfect sunny. And light bulbs aren't particularly heavy
electricity users compared to refrigerators, televisions, and electric
ovens. It takes a lot of area covered with solar panels to
run a house in the manner most Americans are accustomed to running it.
So what can the
average suburban American do with
solar cells? Potentially the most practical use I
have found for solar
cells is in battery chargers. You can charge most
rechargeable
batteries--Nickel Cadmium and Nickel Metal Hydride batteries--in a
variety of
relatively inexpensive solar battery chargers. Charging them
that way
takes considerably longer than using a charger that you plug into the
wall, but
the solar charger allows you to recharge batteries anywhere where there
is sun,
so a solar charger might be useful if you're tent-camping in an area
with no
electricity. Unfortunately, there are a lot of solar battery
chargers out
there that simply don't work very well, so you might want to do some
reading up
before you buy.
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