Given all these uncertainties, how should investors place their bets on renewable energy?

Over the next few years, solar-power capacity will continue to expand, fueled by utility-scale projects such as NRG Energy’s (NYSE: NRG) Ivanpah facility and a growing number of rooftop installations.

Opponents of investment tax credits for solar power likely won’t have enough votes after the upcoming Congressional election to override President Barack Obama’s veto and repeal these subsidies.

At the same time, any rollback of states’ renewable portfolio standards will occur gradually, even in areas where opposition has strengthened.

Consumer demand for rooftop solar remains high in affluent states with higher electricity rates. And solar power has emerged as a viable alternative to oil-fired power plants in Hawaii and the US Virgin Islands.

NRG Energy, for example, recently acquired a 4-megawatt solar farm in the US Virgin Islands that operates under a 25-year contract.

Hawaii is perhaps a more critical test case than California for the large-scale viability of rooftop solar and other forms of renewable energy.