In most of the markets my company is active in, solar is close enough to grid parity that it can no longer be considered “too expensive” or “not efficient”.  Colleague Aidan Foley has a great post that 50% of US markets are now solar-ready.

Now it’s about discovering what the off-taker’s investment threshold is, and how you compete for investment dollars.

Most of my corporate customers use discount rates of seven to nine percent—solar now meets that easily with the value put on RPS compliance using tradable RECs.  Investment solar gives you mid-teens returns if you are a corporate owner [not subject to passive loss restrictions].  Not a bad return on investment given the low risk of solar energy production.