There is more than one way to generate electricity from sunlight but, in practice, virtually all solar electricity generation in the world uses photovoltaic cells, also known as solar PV. Photovoltaic modules (or PV modules) are generally mounted in metal frames and installed in ‘arrays’. Typically one or two m2 (10 to 20 ft2) per module, they can be wired together to create arrays of several kW (1,000 Watts) or even MW (1,000 kW). Apart from its dependency on the sun as the direct source of its energy, PV has little more in common with solar thermal collectors than that they are often found on the roofs of buildings, oriented towards the best possible view of the sun’s path. PV modules generate electricity while solar collectors absorb heat.