[SGVLUG] Off-topic - home guerrilla solar systems

[David Lawyer]

On Fri, Feb 23, 2007 at 08:07:00AM -0800, Don Gibbs wrote:
> While the group entertains this off-topic thread ...
> 
> I've wondered about the long-term benefit of PV (photovoltaic) 
> systems.  I've done a some searching but have not seen any decent 
> analysis evaluating the overall energy efficiency  of such systems. 
> For instance, for a non-steerable, residential system capable of 
> delivering 1kW peak (noon, mid-summer, surface normal to sun) in the 
> LA area and tied to the neighborhood utility, how much total energy 
> was required to build and install it and how much total energy will 
> it deliver over a ten year period?  I suspect the payback is pretty 
> good.  But my gut judgements have proven wrong before.

If it costs less for electricity this way, then it likely will use
less energy.  All energy (including labor energy) get added to costs
so this is about the best criteria we have for estimating energy
content.  I've read that PV will cost more for electricity so if
that's the case then it's a loser.  Another unknown is how long the PV
installation will last.  You also need to include the cost of
batteries.  The cost method of estimation of energy content has been
widely used for decades.

Here's an important paper on PV economics from profs. at the Naval
Postgraduate School at Monterey, CA.  They seem to agree with me and
conversely.
http://www.nps.navy.mil/drmi/WorkingPapers/DRMI%20Working%20Paper%2006-02.pdf

			David Lawyer