Land Art Generator Initiative :: Renewable Energy Art & Design

Photovoltaic
The Photovoltaic effect, first recognized by A. E. Becquerel in 1839, is the ability of a material (a semiconductor) to produce direct current electricity when exposed to solar radiation. It is related to the photoelectric effect, which is the ejection of an electron from a material substance (usually a more highly conductive metal as opposed to a semiconductor material) by electromagnetic radiation incident on that substance. However, in the photovoltaic effect, the electrons remain within the material (by the nature of the material) creating positive and negative bands which can be harnessed by an electrical circuit.

Thought the effect was demonstrated in various laboratory applications throughout the 19th century, it was not until 1954 that the first commercially viable application of the technology was demonstrated by Bell Laboratories.Throughout the PV section we will discuss conversion efficiency. A good rule of thumb is that one square meter surface area (at sea level and perpendicular to the sun on a clear day) will typically receive 1000 watts of solar radiation energy (insolation = 1000 watts irradiance/square meter ). This measure will vary slightly according to latitude, time of day, and season. The conversion efficiency is how many of those 1000 watts can be converted electrical energy by a solar cell that covers that entire square meter of area. If the 1m2 solar cell can generate 250 watts of useable electricity at any one time it can be considered to have a 25% conversion efficiency. If that 1m2 solar cell operates at its rated capacity (250watts) for 6 hours, it will have produced (250 x 6 = 1,500) 1.5 kilowatt-hours of electricity. Many other factors can contribute to a reduction of rated capacity in field applications such as heat build-up, humidity, surface dust, and airborne particulates.