How Does It Work?
Solar cells convert the sun's energy into electricity through the photoelectric affect; the ability of matter to emit electrons when a light is projected on it.
Silicon is what is known as a semi-conductor, meaning it shares some of the properties of metals and some of those of an electrical insulator. Sunlight is composed of tiny particles called photons, which radiate from the sun. As these hit the silicon atoms of the solar cell, they transfer their energy into loose electrons, knocking them off the atoms. The photons could be compared to the cue ball in a game of pool, which passes on its energy to the colored balls it strikes.
Freeing up electrons is only half the work of the solar cell though. The cells then need to pull the stray electrons into an electric current. This involves creating an electrical imbalance within the cell, which acts a bit like a slope down which the electrons will flow in the same direction.
Creating this imbalance, and all of this is made possible by internal organization of silicon. Silicon atoms are arranged together in a tightly bound structure. By squeezing small quantities of elements into this structure, two different types of silicon are created: "n-type", which has spare electrons, and "p-type", which is missing electrons, leaving "holes" in their place.
When these two materials are placed side by side in a solar cell, the n-type silicons spare electrons jump over to fill the gaps in the p-type silicon. This means that the n-type silicon becomes positively charged, and the p-type silicon is negatively charged, creating an electric field across the cell. Because silicon is a semi-conductor, it can act like an insulator, maintaining this imbalance. As the photons smash the electrons off the silicon atoms, this field drives then along in an orderly manner, providing the electric current to power anything.
As the sun's rays hit the solar cells, electricity is generated in what is known as DC power, that electricity then moves to your inverter, and then to the control panel of your home where anything plugged into an outlet receives power. This conversion takes place in the inverter and is known as AC electricity. In an on grid-system, excess energy is fed back to the power company where they have to pay back the energy they receive dollar for dollar watt for watt.
At night when the sun is not shinning and this conversion is not taking place, electricity is fed to your home through the power grid, as it would normally. There is no difference in performance or power, in fact the only difference you will see is on the utility bill at the end of the month.
Off-grid systems go through a similar process, however batteries are used to feed the energy into the home, RV, boat, etc.