Energy Payback

Several studies have be done to calculate the embodied energy in a PV panel and to then demonstrate that the energy investment is paid back in a short period of time; 1-4 years is commonly claimed. But this does not ring true in light of the very poor economic return. As discussed in "PV Economics", the price of installed grid-tied PV systems need to fall almost by a factor of 10 to make them truly competitive with fossil fuels. These papers use a bottoms up analysis which traditionally underestimated total energy inputs, and they are written by people that are strong solar advocates. Such bottoms up analysis are extremely difficult to make complete.

One reliable way to know the real energy content is to observe the change in price of the panel as energy prices change. If energy cost increased 10% and the panels increased 2%, then we could say the embodied energy is 20% of the total cost. This method automatically captures 100% of the embodied energy cost. Of course, asking all other variable to stay constant during the test is a tall order.

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