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. The underlying method they employ however dates from 1839, when it was discovered by Becquerel who found that shining sunlight on an electrolytic cell would produce a current.

Other scientists built on Becquerel’s work. Albert Einstein is most well known for the Theory of Relativity however, 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 similar to what solar power enthusiasts and workers know as the photovoltaic effect, the principle first found by Becquerel. When light, (in this case light from the sun) strikes certain materials it knocks loose electrons from their associated atoms it is these moving electrons which create a current that can flow through the material to provide electrical power.

Today’s materials are typically some type of doped silicon. ‘Doping’ is another way of saying that other elements are deliberately introduced into the material. Such impurities would be undesirable in other applications however, in solar power, they are essential. Pure silicon has its uses, but it’s not a good conductor of electricity adding phosphorus in the correct manner turns them into semiconductors.

Certain specialized applications use gallium-arsenide or other materials, instead of silicon but their relative rarity means the cost is much higher. Silicon, on the other hand, is a major component of ordinary sand and therefore plentiful.

The silicon-phosphorus compound is arranged in layers and then connected to a grid to enhance the flow of electricity; the compound also 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 protective glass to protect it and forms what is known as a PV (photovoltaic) cell. These cells are then arrayed into a module and these modules can then be connected together into a complete system.

The modules come in a variety of 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 that reaches the surface (at the equator) is about 1,000 watts per square meter although not all of it is usable energy. A square meter is a square where the 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 is heavily dependent on increasing that efficiency and lowering production costs. That efficiency is bound to a certain degree by particular difficult-to-get-around physical constraints, so most of the research efforts center on lowering the manufacturing costs.

When and if that happens, solar power applications may well become even more evident in homes and businesses than they are today.