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How Solar Power Works
Solar power, particularly when it's used to provide home electricity needs, may seem like a relatively recent invention. And it's true that large, cost-effective panels that form the core of most systems have only been in use for about that past 30 years. But the underlying method they employ goes back to 1839, when it was discovered by Becquerel. He found that shining sunlight on an electrolytic cell would produce a current.
Other scientists built on that work. In fact, while Albert Einstein is most well known for the Theory of Relativity, he received his 1921 Nobel Prize for something quite different. According to the Nobel organization it was 'for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect'. His paper on the subject was written in 1905.
The photoelectric effect is essentially similar to what solar power enthusiasts and workers know as the photovoltaic effect, the principle Becquerel first found. When light, in this case from the sun, strikes certain materials it knocks loose electrons from their associated atoms. Those moving electrons create a current that can flow through the material to provide electrical power.
Those materials today are typically some type of doped silicon. 'Doping' is another way of saying that other elements are deliberately introduced. In other applications, those impurities would be undesirable. In solar power, they're essential. Pure silicon has its uses, but it's not a good conductor of electricity. Adding phosphorus in just the right way, for example, turns them into semiconductors.
Certain specialized applications use gallium-arsenide or other materials, instead of silicon. But because of their relative rarity the cost is much higher. Silicon is a major component of ordinary sand and hence plentiful.
The silicon-phosphorus compound is arranged in layers, then connected to a grid to enhance the flow of electricity. It reduces the resistance losses. Then terminals are installed to allow for the electricity to flow into the home electrical system. The whole assembly is covered with glass to protect it and forms what's known as a PV (photovoltaic) cell. Those cells are then arrayed into a module. Modules can then be connected together into a complete system.
Those modules comes in various sizes that determine how much electricity they generate. All other things being equal, the larger the area, the more power they can produce. Naturally, the larger panels tend to cost more.
Though the solar energy reaching the surface (at the equator) is about 1,000 watts per square meter, not all of it is usable energy. A square meter is a square whose sides are a little larger than three feet - it's about 10.7 square feet. Apart from losses due to latitude, atmosphere, dust and other natural factors, the modules themselves only convert with about 10-15% efficiency.
The growth of solar power as a practical energy production method depends heavily on increasing that efficiency and lowering the costs of production. To a degree, that efficiency is bound by certain difficult-to-get-around physical constraints, so most of the research efforts involve attempts to lower the manufacturing costs.
When or if that happens, solar power applications may well become even more commonplace in homes and businesses than they are today.
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