CPS has a program, but I've not looked into it in forever. My neighbor just started digging into it, and it turned into an HOA fight.
Dude at work had one of the door to door guys hit him up. He was kind of excited about the idea, but it sounded like fool's gold at first. A whole bunch of the savings, it would seem, were based on energy costs more than doubling in the next X years. He was going from memory at the time, but it also involved what seemed to me a stupid high payment for an extended period of time. I told him to ask the door guy for the nuts and bolts of how they model the system to project available energy, and what the expected payback period was. Over the phone the door guy said he had it all handy "once he got back to the office," but I don't think anything was ever provided.
In a past life, I worked for a GC who did a bunch of government/DoD work. There was a niche market with the Air Force doing solar and PV projects. Or rather, TRYING to do solar and PV projects. It was in many cases difficult to get the numbers to work. It lead to other design-build teams playing games. You can tweak all kinds of things to skew numbers - panel temperatures, ratings, available sunlight, etc. Two things were also very eye opening: 1. the volatility of solar panel prices (they've dropped quite a bit since then) and 2. the number of solar companies that come and go. The latter seems to be more the rule than the exception.
All of that is to say this, I don't have a dog in the fight, but I'd probably start looking at one of the CPS deals before a door to door guy. CPS has its share of faults (no pun intended), but their end game is enticing customers to lease their roofs in order shave demand and push out the capital costs for new generation. Door guy's end game is to sell you solar panels.
A friend of mine is the renewable energy manager at a local co-op. They're rolling out a program similar to what other utilities have done, and by leveraging their name and number of customers, they've been able to get the dollars per watt numbers really competitive for a turn key install.