Thanks for your comment. I don't think that a solar lease is any less sustainable than a direct solar purchase when it comes to the impact of the tax credits on tax payers. In either case, it's the same 30% federal tax credit and the same local tax credits whether it's the home owner applying for them or whether it's a solar leasing company applying for them. In fact, the leasing companies get a better deal on the panels & BOS because they buy in volume, so they would be getting a credit on a smaller amount which means that tax payers would be subsidizing a smaller amount.
I haven't done much analysis on whether all of our various tax credits are sustainable... although I sure hope they are. That said, in PG&E territory the price of panels is coming down about as fast as the rebates are drying up, so in that case the finance seems sustainable since it is due to run out pretty quickly.
Solar leasing is by no means a silver bullet or a perpetual motion machine. However it does allow people who have a good credit score (generally that means over 700) to go solar by paying less per month than they currently do for their electricity bill, rather than paying $15 or $20k (or more) up front for a system. In the long run you save more money if you buy the system outright from the start. But for many homeowners they'd rather just reduce their monthly expenditure on electricity via a solar lease, even though the savings won't be as great over the next 20 years.