"Old Nick" wrote in message
...
On Sat, 28 Feb 2004 20:48:35 GMT, "Ed Huntress"
vaguely proposed a theory
......and in reply I say!:


What is the source for the claim that solar electricity has a 2-5 yr.
ROI,
Larry? The figures I've seen show a payback period of...never.

There was one claim here, I can't remember by whom, that solar power
actually had a negative _energy_ valkue, in that it took more energy
to make a solar cell and the associated batteries etc than it
generated in its life.

I don't know what the present status is, but that was the case at least 15
years ago. Someone I talked to around that time who seemed to know what he
was talking about (he was an engineer for a company that did process work on
manufacturing of semiconductors) said that the life of PV cells had passed
the threshhold, and that some cells made at that time (early '90s) were
producing positive net lifetime energy. Gary C. probably knows more about
this.

Guessing here, a large portion of the lifetime energy of those cells
probably is still lost to the manufacturing-energy overhead.

Ed Huntress