Making a solar power home has been a dream in the environmental sector for many years, and there are a lot of ways to achieve it, though none are quite there yet. The two most common ways to make a solar efficient or solar power home are through solar thermal systems and solar power kits, which use photovoltaic systems to convert sunlight into electricity. We're going to discuss photovoltaic systems as part of solar power kits today and cover solar thermal another time.
Solar power kits sell pre-packaged sets of individual solar power cells that are wired into arrays to provide useful voltage and current levels, usually they're panels with 36 cells apiece for reasons of voltage and current draw. However, there's a bit more to how those solar power cells work that makes for interesting reading.
Semiconductors And Photons
Solar power cells (like those found in solar power kits) are made up of silicon wafers. They're made so that when sunlight hits one part of the cell, it shakes electrons loose which then migrate to another part of the cell; this creates a current and is how the solar power cell generates electricity. Because silicon is a semiconductor (meaning that it can have electricity go in one direction through it), this allows sunlight to go into the solar power cell and electricity to come out the other side. This electricity is a function of the differential between two different forms of crystalline silicon.
A silicon atom has 14 electrons arranged in three shells of potential. The outer shell is half full, having 4 of 8 electrons filled. As a result, the silicon atom has, for a lack of a better term, sockets for other electrons to fill; when in crystalline form, it will share electrons with the four closest silicon atoms to it. In its pure form, crystalline silicon is a poor conductor of electricity, because none of those electrons are free to move about. (Electrical conductivity is a function of electrons moving from atom to atom.)
To use silicon as a semiconductor (necessary for use in a solar power kit), you dope it with other elements, called impurities. These doped compounds will bond with silicon atoms in a lattice and give it a way to conduct electricity; more to the point, the doped compounds allow electrons to be shaken loose a little bit more easily. This means that when energy comes into the silicon, it more readily shakes electrons use. For type N (or negative valence silicon), the doping is with phosphorous (which has 5 electrons in its outer shell), and that means that the silicon is likelier to shake an electron loose, making a negative potential. For type P (or positive valence silicon), the silicon is doped with boron, which has 3 electrons in its outer shell, making it likelier that there will be a gap in the electron shells for an electron to fall into. N type silicon is a very good conductor, while P type silicon is a good resistor.
A solar power cell has a layer of N type silicon over a layer of P type silicon; the N type silicon gets hit by solar photons, which shake electrons loose; if the photons are energetic enough, the electrons will be released with enough energy to cross over from the N type silicon to the P type silicon and this creates a current. That current is then run through an inverter and stored in batteries for your solar power home.
And now you now know solar power cells work, and can understand a bit of the physics behind a solar power kit as you install them for your solar power home.
