I don't really understand the difference made here between commercial solar tech and individual solar tech?

Thermic solar exists in different technology, all of them of some use, the simplest being a black-painted water barrel on top of one's house. They are hardly the most expensive.

Solar PV is still economically unsafe at the moment, but the tech is the same for commercial or individual installation, the pannels being standard-sized. The tech difference here is between low yield silicium pannels and high yield GaAs ones. None of these are economically sustainable at the moment, but the research is very active here.

It's the individual/commercial PV that is badly in need of tariff feed-in, because individual thermic solar is used for hot water generation, not electricity. I don't know the economics of industrial thermal (hot water+turbine+generator) but I think it should be similar to gaz turbine generation regarding the capital investment.

Should your diary be understood as a critic of solar PV, both commercial or individual? If so, the question is more on this particular technology than on solar in general.