turbo36
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Turbo36,
The reason I am skeptical of the 1.5 year energy payback claim is that, if it were true, they would be installed. Everywhere. The basic raw materials are quite cheap.
The total energy required is not the energy to run the machine that makes the substrate, and subsequent chip. The true energy hogs are the feedstock processing, along with the astoundingly low yield associated with effort to make the feedstocks. I suspect that someone used the heat of melting of silicon as a basis for that claim, and it has been propogated as an urban myth.
Again, I would like a reference to the specific article that supports the claim, if you have one, as I would like to study it. I may get my eyes opened. It would help me out a bunch.
Thanks for you help.
Chris
Research these articles to see the real and potential solar payback periods. Most of the studies showing long paybacks are 5-15 years old so they are not relevant when comparing today's technology.
According to Wikipedia:
Solar cell - Wikipedia, the free encyclopedia
Energy payback is the recovery (period) of the energy spent for manufacturing of the respective technical energy systems, also called harvesting ratio (ISO 13602).
In the 1990s, when silicon cells were twice as thick, efficiencies were 30% lower than today and lifetimes were shorter, it may well have cost more energy to make a cell than it could generate in a lifetime. In the meantime, the technology has progressed significantly, and the energy payback time of a modern photovoltaic module is typically from 1 to 4 years[8][31] depending on the type and where it is used (see net energy gain). Generally, thin film technologies - despite having comparatively low conversion efficiencies - achieve significantly shorter energy payback times than conventional systems (often < 1 year).[32] With a typical lifetime of 20 to 30 years, this means that modern solar cells are net energy producers, i.e. they generate significantly more energy over their lifetime than the energy expended in producing them.[33][8][34]
Other sources:
http://www.nrel.gov/docs/fy04osti/35489.pdf
Entropy Production: Solar Payback Period
Solar Urban Legends - greentechZONE
Alternative generation and storage methods
Technology Review: Solar without the Panels
China has more coal then we do but they are moving fast into renewable energy sources
China links coal use and birth defects - 02 Feb 2009 - BusinessGreen
Updated: China overtakes UK as top location for renewables investment - 19 Aug 2008 - BusinessGreen
China's rise in solar energy centered around polysilicon; LDK signs contract with Italy's Helios
Even the utilities are embracing solar
Duke Energy pushes for rooftop solar distributed power program