Solar Cells

You've probably seen calculators that have solar cells --
calculators that never need batteries, and in some cases
don't even have an off button. As long as you have enough
light, they seem to work forever. You may have seen larger
solar panels -- on emergency road signs or call boxes, on
buoys, even in parking lots to power lights.

Although these larger panels aren't as common as solar
powered calculators, they're out there, and not that hard to
spot if you know where to look. There are solar cell arrays
on satellites, where they are used to power the electrical
systems.

You have probably also been hearing about the "solar
revolution" for the last 20 years -- the idea that one day we
will all use free electricity fro­m the sun. This is
a seductive promise: On a bright, sunny day, the sun shines
approximately 1,000 watts of energy per square meter of the
planet's surface, and if we could collect all of that energy
we could easily power our homes and offices for free.

we will examine solar cells to learn how they convert the
sun's energy directly into electricity. In the process, you
will learn why we are getting closer to using the sun's
energy on a daily basis, and why we still have more research
to ­do before the process becomes cost effective.