This is what plants do through photosynthesis, using light to bind carbon from the atmosphere to sugars that they metabolize and grow. The solar panels you’re seeing on more and more rooftops do something similar, converting light into electricity. They can do this because of the so-called photovoltaic effect, which converts solar energy into electricity. Here’s how it works: Sometimes, when light hits an atom, it gets absorbed by an electron around the atom, boosting the electron’s energy. In some materials, such as some metals and silicon, this extra energy is enough to cause electrons to free atoms, allowing them to move within the material’s crystal structure. If you create two crystal layers, you can use it.
One layer, called n-type material, is contaminated with a chemical (scientists call it a stimulant), meaning it has a lot of electrons, so it has extra electrons. The other layer is contaminated with another material that makes it want to absorb more electrons, called a P-type material. These electrons do not easily jump over the junction of the two materials (called an NP junction), so there is a voltage difference between the two layers. If you then connect the circuit to each side of this panel, this voltage can be used to power the device or charge the battery. Each solar cell generates only a small voltage, typically about 0.5V. The amount of current created depends on the size of the cell. This voltage can be increased if multiple batteries are connected together. So if you connect solar cells together to cover your roof, you could get enough electricity to power most of your house. Solar panels also generate direct current, rather than the alternating current provided by utilities. This means that the energy from the solar panels must be converted before it can drive the toaster. It also often requires storage: you might want to bake bread when the sun is down, and solar panels don’t generate electricity in the dark.
Of course, this depends on the amount of light being converted, and there are other limitations to the process. The energy they capture depends on the nature of the light-absorbing material and the connection between the two materials. The combination absorbs only certain frequencies of light. Some modern solar panels get around this problem by including multiple materials and connections between them (called multi-junction cells) that can absorb light at different frequencies to capture more of the available energy. Have a cost. Solar cells are not cheap to make because they need to grow large crystals with accurate chemical composition. Other parts of the system, such as controllers, are also expensive because they need to be able to handle large amounts of energy. It is estimated that only about 7 kilowatts of energy can be generated by providing solar panels. There are 490 square feet of solar panels on the roof.