How green is a solar panel?

There are three main types of solar panel, monocrystalline, polycrystalline and amorphous. Each type has it's own cnaricteristics and environmental impact. Monocrystalline solar cells are made from thin wafers of silicon, sliced from large crystals that have been grown under carefully controlled conditions. This process is very complex and energy intensive. Polycrystalline panels are slightly cheaper to produce, as the manufacturing conditions are less demanding. In this form a number of interlocking silicon crystals grow together. Panels based on these cells are cheaper per unit area than Monocrystalline panels, but they are slightly less efficient. Amorphous silicon panels don’t use silicon in crystal form, instead the silicon is deposited in a very thin layer on a backing substrate (Aluminium for example). Sometimes several layers of silicon doped in slightly different ways to respond to different wavelengths of light are laid on top of one another to improve the efficiency. The production methods are complex, but less energy intensive than crystalline panels.

Chemical contamination

Current PV technologies lead to cadmium emissions of 0.3-0.9 microgram/kWh over the whole life-cycle. Most of these emissions actually arise through the use of coal power for the manufacturing of the modules, and coal and lignite combustion leads to much higher emissions of cadmium. Life-cycle cadmium emissions from coal is 3.1 microgram/kWh, lignite 6.2, and natural gas 0.2 microgram/kWh. Note that if electricity produced by photovoltaic panels were used to manufacture the modules instead of electricity from burning coal, cadmium emissions from coal power usage in the manufacturing process could be entirely eliminated.

Lifetime embodied energy

In 2000 the energy payback time was estimated as 8 to 11 years, but more recent studies suggest that technological progress has reduced this to 1.5 to 3.5 years for crystalline silicon PV system. Life cycle greenhouse gas emissions are in the range of 25-32 g/kWh. For comparison, a combined cycle gas-fired power plant emits some 400 g/kWh and a coal-fired power plant 915 g/kWh

Recycling and material recovery

Getting the silicone out of a solar panel and recycling it sounds like a challenge, There is very little information about the costs and techniques for recycling pv solar panels.

Factoids [2]

The use of germanium in amorphous silicon-germanium thin film solar cells provides residual power generating capacity at night due to background infrared radiation.

Any Answer to finding and implimenting new ways of producing power for the millions of users is based on wether the new source requires mechanical or moving parts so that the producer can make a future profit on the sale of replacement systems or spare parts as the moving parts wear out. Any system that has no moveing parts such as Solar Panels means little or no futur of making a profit for the producer or investor. This is why there is a lot of investment and plans for Windmills which have moving parts. And little or no investment or Plans for Solar Panels becasuse they have no moving parts.

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