[fgm2r]

According to [1] photovoltaic energy might be competitive in Germany by 2012/2013 in regions with a lot of sunshine and by 2016 "in regions with less intensive sunshine." (I'm not sure whether "less intensive" means average.) These numbers assume consumer prices and no subsidies. For industry users competitiveness is expected by 2019.

Hawaii: already competitive (2009), California: 2011 (assuming 3kW plants)

Reuters [2] writes that "very sunny countries could reach that breakeven in five years[2012] or so, and even cloudy Britain by 2020."

The breakeven is called Grid Parity http://en.wikipedia.org/wiki/Grid_parity

[1] http://www.wm.baden-wuerttemberg.de/fm7/1106/Endbericht%20Br... (German, 2009, this is the report cited by taz.de)

[2] http://www.reuters.com/article/2007/10/19/environment-solar-... (2007)

[roel_v]

This doesn't answer his question, but anyway: it depends on how you account for things. When you take into account the production cost and materials needed for PV, electricity from them is not a sustainable energy source in any non-marketing meaning of the word.