solar cells were first seen on calculators that never need batteries, and in some cases don't even have an off button.
solar cells bidden together in large panels aren't as common as solar powered calculators, but if you look hard you could spot solar cells. There are solar cell arrays on satellites, where they are used to power the electrical systems.
Invention of solar cells gave birth to the concept of "solar revolution" the idea that one day we will all use free electricity from the sun with the help of solar cells. 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.
