For those of us that have considered investing in solar energy to slash energy bills, increase property value, protect the environment, and decrease our dependency on fossil fuels, most have wondered how solar panels actually work. Even though the intimate details and mechanics of how they produce energy are beyond most people’s understanding of science and physics, it is relatively easy to understand how solar panels generate electricity – at a basic level, at least. It is no surprise that the sun produces an almost unlimited amount of energy, so if you plan to save your hard-earned money with solar, you should have a rudimentary knowledge basis of how solar panels turn light into electricity.
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Solar panels are composed of many individual solar cells, and each cell is composed of a semiconductor called silicon. This silicon is layered within the cell, but each layer has a different function. One layer (made of N-type silicon) has extra electrons while the other layer (made of P-type silicon) has extra ‘electron holes’ capable of accepting electrons. When electrons cross between the two layers, they can leave one side positively charged while the corresponding layer is negatively charged. But how does the sunlight come into play?
Particles of Sunlight and Photons
Well, light energy is really a stream of extremely fast moving particles called photons. When the photons strike the silicon to transfer energy, they actually knock an electron out of its bond with atoms in the silicon. The electron, being negatively charged, will be drawn to the negative layer of silicon. On the other hand, the ‘hole’ or gap the electron previously occupied will be drawn to the positive layer. The electron can only travel one way because of the layers’ corresponding charges.
The electrons that get knocked out of their bonds are then collected by tiny conductors spread out through the cell. After the electrons are collected, they are pushed through a circuit of least resistance until they reach a device that wants to use their energy, such as a light bulb or television. Though solar panels don’t have any moving parts in the conventional sense, you might call electrons the only moving parts in this form of technology.
Why Solar Panels are Less Efficient on Cloudy Days
After you have a basic understanding of how a solar panel works, you begin to understand why direct sunlight is best for optimal efficiency. On cloudy days, more light photons are filtered through obstructions than on clear days, so fewer photons have the opportunity to strike electrons in the silicon. In addition, excessive dirt, snow, or other obstructions on the solar panels will also block photons and prevent them from striking electrons in the silicon layers.
For those of you who decide to invest in solar technologies to save boatloads of money and decrease your dependence on fossil fuels, this should help you develop a basic understanding of how they function.