I thought to go into some details on Ad 1.

First, on the geographic aspects.

• Rooftop solar and both domestic and MW-scale wind share a benefit compared to greenfield solar farms of either type (large-scale PV, concentrated PV [CSP] and solarthermal): they take away little or no real estate. Thus, greenfield solar can have a significant contribution only in places with lots of cheap desert-like area available.
  
• Unlike Germany, Spain is such an area. Thus, contrary to what you write in the diary, the 2008 Spanish PV boom (see stats upthread) was overwhelmingly in large greenfield farms (and large industrial rooftops), not on private home rooftops. While I don't have actual stats for it, one can add up the 2008 Spanish plants in the World's largest photovoltaic power plants ranking: just the farms 2MW or above add up to 2096 MW, out of the 2700MW total. (Out of the 3400MW added in Germany this year, the same number is just 517 MW.)
  
• It also helps that apparently, Spain has no separate FIT rates for greenfield and rooftop (in Germany the first is lower).

Second, all renewable technologies can be considered evolving technologies, for which the price per kWh as a mature technology can only be projected. These projections come with differing certainty, however, given the different stages of evolution these technologies are in. And this is where the relationship of domestic wind and large wind, and that of PV and CSP or solarthermal is inverted: in the eighties already, large wind was an industry producing in large series, while small wind still remained at backyard shop level to this day; while in solar, PV is the well established industry with factory-size series production, and CSP and solarthermal are still in the pioneering phase.

That is, one can infer with some certainty that PV and MW-scale wind will be able to cut prices further according to projections, while CSP, solarthermal and domestic wind have yet to prove their claims. (What could be the risks for CSP or solarthermal? Maintenance/leaks, for example.)

Finally, there is also the issue of the rate of production. It remains to be seen whether CSP or solarthermal plants can be projected, approved, manufactured and installed at an annual rate in the Gigawatts, like large wind and PV showed that they can.

_{*Lunatic*, n.
One whose delusions are out of fashion.}