People are talking a great deal about solar energy as the future of renewable energy, but how does it really work?
Solar panels look kind of simple, but in fact crystalline polysilicon, the most common choice for solar panels, and monosilicon solar panels are made up of several layers. The top layer, or cover glass, acts like a shield for the small units within the panels solar cells. If you could peel back the top glass layer, you would find an antireflective coating underneath on a second glass layer. The antireflective layer is dark, so the sun’s energy can be absorbed and not reflected back into the atmosphere. Without this layer, over thirty percent of the light entering the solar panel would be reflected away from the solar cells, and nonproductive in generation of electricity. The antireflective layer is designed to be transparent enough to allow light to pass through it to the cells, but trap any light being reflected away by the cells.
The next layer is called the contact grid, containing a series of interconnected silicon cells, that form a circuit. Solar cells held in the grid have two layers of semiconductor silicon(Si). Both layers are doped, or have added elements to enable the generation of electricity. This doping creates a layer of n-type Si containing more electrons, and p-type Si, or positive Si with more protons. When the layers are joined together, they form a p-n junction with an electric field between them. When the photon energy reaches the lower layer, electrons start flowing. Each solar cell can generate 0.5V to 0.6V of electricity, or enough to power a cell phone or calculator. Most solar panels contain 60 to 72 solar cells. An array, or group of panels is then used to generate enough electricity to power an entire household or business.
Traditionally, there is then a protective back contact layer, or backsheet. Backsheets adhere to the backside of modules to provide electrical insulation, much the same way porcelain was once used on fuses in an electric fuse box. And of course, there is usually an aluminum frame to finish the module. The frame strengthens the panels and protects the glass edges, which makes racking and mounting systems more efficient.
The crystalline monosilicon solar panels have layers similar to the polysilicon solar panels, but the cells are produced by growing a single silicon crystal. There is less of a jeweled, or faceted look in the monosilicon solar panels, due to the single crystal cylindrical ingots used to produce them. Monosilicon cells carry a higher efficiency rating but there is a lot more waste when producing those single crystal cells, leading to higher production costs. Recently, polysilicon technology has improved enough that in better polysilicon panels, the performance variance between the two silicon solar panels is slight, while the cost difference is more significant.
Thin film solar panels are becoming more popular for the aesthetic value to homeowners and businesses. A thin semiconductor is laid on glass, plastic or metal foil. Because it is so thin, it has been used on curved roofs, automobiles and other unique installations. The three most common thin film types are amorphous silicon , cadmium telluride, and copper indium gallium selenide. Because the film is so thin, less material is required to produce the panels, but thin film panels also have lower conversion efficiencies than silicon.
Knowing how solar panels work won’t change the savings or the freedom from electric bills you can enjoy once you do convert from fossil fuels to solar energy, but it does help you understand what those panels can do and which panels make sense for your application. Renewable Solar Resources is expert at analyzing panel location and type, as well as ensuring correct professional installation of the different types of panels homeowners and businesses prefer. Visit http://www.renewable-solar.com/ or call (888) 432-9024 and schedule your consultation today.