How Does Photovoltaic (PV) work?

PV cells are normally fabricated using special semiconductor materials that allow electrons, which are energized when the material is exposed to sunlight, to be freed from their atoms. Once freed, they can move through the material and carry an electric current. The current flows in one direction (like a battery), and thus the electricity generated is termed direct current (DC). The energy generated by PV modules can be used immediately or stored in batteries for later use. Normally, the excess energy generated in autonomous PV systems during sunny periods is stored in batteries. The batteries then provide electricity at night or when there is not enough solar radiation. For these applications, the number of watts in the array and the capacity of the batteries are carefully sized to give optimum performance.

PV systems generate DC electricity only, usually at the rate of 12 and 24 Volts. Therefore, and in order to operate the household appliances that usually require 110 or 220 AC the system deploys a device called inverter to change the 12 or 24 Volt DC power generated by the PV into AC power of the required 110 to 240 volt.  Charge controllers are used to control and optimize the amount of current flowing into the system from the PV solar panels.

The strength of a PV cell is measured in kilowatt peak (kWp) - that's the amount of energy the cell generates in full sunlight.