How solar cells works
Photovoltaic, pronounced fotovoltayik, comes from Latin: photo (meaning light) + voltaic (meaning energy).
Producing electricity with photovoltaics (PV) emits no pollution, produces no greenhouse gases, and uses no finite fossil-fuel resources. The environmental benefits of PV are great. But just as we say that it takes money to make money, it also takes energy to save energy. The term "energy payback" captures this idea. How long does a PV system have to operate to recover the energy-and associated generation of pollution and CO2-that went into making the system, in the first place? Research shows the energy payback to range between 1 and 3 years. For more details please read this PDF document about pv payback.
Photovoltaic (PV) cells
A PV cell is made up of two thin layers of semi-conducting material (silicon) that generate electricity when exposed to daylight.
When light shines on a PV cell the material absorbs some of the light particles called photons. When a photon is absorbed, an electron is released within one layer of the semi-conducting material.
These "free" electrons will be attracted towards the other layer of semi-conducting material so they move across the boundary between the layers.
This movement creates a flow of electricity between the two layers within the cell. This flow is called "current".
Metal contacts (the silver looking solder) take the electricity away in the form of a direct current (DC electricity).