Solar photovoltaic panels

Photovoltaics (PV) is a term which covers the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, , and electrochemistry.

A typical photovoltaic system employs solar panels, each comprising a number of solar cells, which generate electrical power. PV installations may be ground-mounted, rooftop mounted or wall mounted. The mount may be fixed, or use a solar tracker to follow the sun across the sky.

Solar PV has specific advantages as an energy source: once installed, its operation generates no pollution and no greenhouse gas emissions, it shows simple scalability in respect of power needs and silicon has large availability in the Earth’s crust.

PV systems have the major disadvantage that the power output is dependent on direct sunlight, so about 10-25% is lost if a tracking system is not used, since the cell will not be directly facing the sun at all times. A device called Solar Path Finder can be used to determine the seasons, months and times of the year that the roof will be in shade. Dust, clouds, and other obstructions in the atmosphere also diminish the power output. Another main issue is the concentration of the production in the hours corresponding to main insolation, which do not usually match the peaks in demand in human activity cycles. Unless current societal patterns of consumption and electrical networks mutually adjust to this scenario, electricity still needs to be stored for later use or made up by other power sources, usually hydrocarbon. For safety reasons, in times of black-outs it is a requirement that the Solar PV System is automatically shut off. Thus Solar PV is not alternative of power generators.

Photovoltaic systems have long been used in specialized applications, and standalone and grid-connected PV systems have been in use since the 1990s. They were first mass-produced in 2000, when German environmentalists and the Eurosolar organization got government funding for a ten thousand roof program.

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