Photovoltaic technology has been around for a while now, the first solar powered calculators where produced by a company called Teal, the Teal Photon was introduced onto the market in 1978, these calculators were powered by a single solar cell and the technology has continued to evolve ever since.
Solar technology is being used for more and more, sun is not all that common in the U.K. but when it is shining its rays generate around 1,000 watts of energy per square meter, solar power is a clean alternative to traditional and rapidly declining fossil fuels. It’s cost effective too, the Sun supplies its power for free so once a solar system is installed can save considerable amounts of cash. Whenever I have seen solar powered road signs and panels on people’s houses, I often wondered how these panels produce power. So I decided to look into it.
When I looked into solar technology I began to find that it is actually quite simple, solar cells are made of special materials; silicon is a commonly used semiconductor material in today’s market. When light strikes one of these cells, a portion of that light is absorbed by the silicon or whatever semiconductor material is being used.
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This bit gets a bit technical, an atom of silicon contains 14 electrons; these electrons are arranged in three different shells. The first shell holds two electrons; the second shell holds eight electrons these shells are completely full. The silicon atoms outer shell is only half full though, it contains four electrons. The silicon atoms always look for ways to fill up their last shell; they do this by sharing electrons with other silicon atoms.
Solar cells usually contain impure silicon, this silicon has phosphorous atoms mixed in, a lot less energy is required to knock loose one these phosphorous electrons because they aren’t tied up in a bond with any of their neighbouring atoms.
This means that when the energy of the absorbed light is transferred to the semiconductor. This absorbed energy knocks electrons loose and allows them to flow freely.
Solar cells contain electrical fields these act to force the loose electrons in a certain direction. This flow of electrons creates a current, metal contacts placed on the top and bottom of the solar cells mean that current can be drawn off and used to power whatever you like.
That’s the basics of solar power anyway, once this energy has been created you need to find a way to store it, how is that done? How is solar energy stored?
Solar energy can be stored in batteries but current battery technology is not advanced enough to ensure a reliable supply of electricity, especially in the U.K. Batteries can also need a lot of maintenance and add a lot of expense to domestic photovoltaic systems. A lot of home owners who wish harness this free power simply supply solar power house to the national grid when they have an excess and buy it back if and when they need.