Earth Equity News

How Does Solar Power Work? By Susannah Locke, SciAmer, October 20, 2008. "The sun's light (and all light) contains energy. Usually, when light hits an object the energy turns into heat, like the warmth you feel while sitting in the sun. But when light hits certain materials the energy turns into an electrical current instead, which we can then harness for power. Old-school solar technology uses large crystals made out of silicon, which produces an electrical current when struck by light. Silicon can do this because the electrons in the crystal get up and move when exposed to light instead of just jiggling in place to make heat. The silicon turns a good portion of light energy into electricity, but it is expensive because big crystals are hard to grow. Newer materials use smaller, cheaper crystals, such as copper-indium-gallium-selenide, that can be shaped into flexible films. This 'thin-film' solar technology, however, is not as good as silicon at turning light into electricity. Right now, solar energy only accounts for a tiny portion of the U.S.'s total electricity generation, because it is more expensive than alternatives like cheap but highly polluting coal. Solar power is about five times as expensive as what people pay for the current that comes out of the outlets. In order to have a hope of replacing fossil fuels, scientists need to develop materials that can be easily mass-produced and convert enough sunlight to electricity to be worth the investment. We asked Paul Alivisatos, deputy laboratory director at Lawrence Berkeley National Laboratory in California and a leader of their Helios solar energy research project, to explain how people capture energy from sunlight and how we can do it better..."