According to this article:

http://solstice.crest.org/renewables/dish-stirling/chapter1/concentrators.html

"With current technologies, a 5-kWe dish/Stirling system requires a dish 
of approximately 5.5 meters (18 feet) in diameter, and a 25-kWe system 
requires a dish approximately 10 meters (33Jfeet) in diameter."

Assuming a garage built amateur system would be 1/10th as efficient it 
means ~0.5kWe from a 6 meter dish at probably 1/100 of the cost of a 
commercial system (which is in the $300k range for this size as I can 
see ?).

Aside: One can buy a ready built and tested ready to go Stirling motor 
that generates 500We for EUR5000 right now. At 19 cents per kW (~EUR 
0.15) it would break even after less than 72k hours ? I think that it 
would be realistic for a garage built one of the same size to make 
250We, and cost less than EUR1000 to make (hours of work not counted). 
Then it would have to run for 25k hours (~3 years) to break even with 
electricity at $0.19/kWh ? (again the calculation above does not account 
for the mirrors and maintenance and installation cost).

Peter
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