Efficiency of the Solar cell
A typical silicon PV cell produces around 0.5 - 0.6 volts direct current (DC) under open-circuit and no-load conditions. The electrical current output of a PV cell depends on its efficiency, size (surface area), and is proportional to the intensity of striking sunlight on the surface of the cell. For example, under peak hours, sunlight conditions, a typical commercially available PV cell with a surface area of 160 cm-2 (~25 in2) will produce around 2 watts power. If the sunlight intensity were 40% of peak, this cell would produce about 0.8 watts. To enhance the power output PV cells are assembled as a solar module in a weather-tight package. These modules (one to several thousand) are wired up in serial and parallel with one another, into a solar array, to create the desired voltage and current output required by the given project.
There are other different types of solar power technologies that including solar thermal and concentrated solar power (CSP) that operate differently than photovoltaic technology, but all harness the power of sunlight or heat to either create electricity or to heat water or air.