Every hour, the
sun showers the earth with more energy than the world's entire
population consumes in a whole year.
There are three main ways to use direct solar energy:
Commercial photovoltaic cells deliver, as electricity, approximately
15% of the solar energy that hits them. Technical improvements are
steadily increasing the efficiency and reducing the cost.
Technically simple solar heating panels can deliver, as useable heat,
about 80% of the solar energy that hits them. Water, sometimes mixed
with anti-freeze, is the usual medium for transferring the heat.
Anyone who has used a clothes line will recognize a good drying day as
one with a breeze and low relative humidity. It takes just a small
temperature increase to cut the relative humidity of air in half,
making all but rainy days good drying days. The required temperature
increase is easily accomplished for high volumes of air with
technically simple solar collectors.