The only renewable energy technology currently capable of surviving without subsidies is biomass.

But no matter where you get the money from needed to finance the subsidies for other, less commercially viable renewables, giving credits or feed-in tariffs really results in a boost to the industry which pays itself back very rapidly.

The German government just recently renewed subsidies for renewables (low amount needed for biomass, higher for wind, very high for solar), but this time was already capable of putting a phase-out mechanism into it.

Meanwhile, the huge number of jobs this sector has created has already paid back the subsidies of the past (more than 400,000 green jobs today; extrapolate this to the U.S. and you'd have 1.6 million new jobs...). The R&D in renewables has made big progress in Germany (see REpower or biogas), and foreign investments have received a boost.

Subsidies, if clearly tied to a mechanism for their re-evaluation and phase-out, do make sense here.