Solar Power
There are two kinds of solar power systems for domestic consumers.
The first generates a supply of warm or (on sunny days)
hot water.
The second gives you electrical energy, which is used to charge lead-acid
batteries. An inverter puts the voltage up to 250. You need a lot of
batteries, and you won't get enough energy to power
kettles or electric ovens.
The main cost of the water-heating system is the installation and
plumbing, though the absorbers (black metal panels or evacuated
tube collectors) are not cheap.
The electrical system uses PHOTOVOLTAIC CELLS. These are
devices which convert from 5 to 10 percent of the sunlight
falling on them into electrical energy. They are constructed of
silicon - either crystalline (very expensive), polycrystalline (a bit
less) or non-crystalline (amorphous silicon; the cheapest). The efficiency is reflected
in the price.
Few photovoltaic cells will generate as much energy in their
lifetime as it
took to make them in the first place. Amorphous cells possibly scrape
under the wire.
Solar panels are becoming a familiar sight
to road users; they often power speed cameras and other
road traffic devices. The box under the pole holding
the solar panel contains car batteries.
Something which isn't so obvious ......
You could class fossil fuels as "solar energy".
All those prehistoric plants,
trees and micro-organisms needed sunlight to grow. Today's plants are solar energy
converters, too. When you burn firewood you're releasing
some of that energy.
For the record, the most efficient plants at converting
sunlight to fuel (known in the trade as "biomass") do it with an
efficiency of about 1%.
OTHER ARTICLES:
How much energy is in sunlight?
