Tim Prosser's numbers are pessimistic. Generally the systems we are installing are about half the price per watt that he's noted. I realize a big part of this is that the new solar incentives are huge. Electricity from the sun at the residential scale here in California costs about $4.10 per watt. Payback times are 5 to 10 years, which is an amazing rate of return for something that is going to last at least 40 years. Every year you wait for new technology, you're losing money; our clients are saving thousands of dollars each year right now.
Steve's great question about lending your rooftop to the utility makes sense except for all the legislation and regulation and policies that have developed over the years. If we could throw all that stuff out and start fresh, distributed, commonwealth-ish power generation is very sensible. The fly in the ointment is that utilities make their money on distribution. This explains why they'll site a generation facility far away from where the load is; they get to have longer transmission lines and higher charges. It's part of how the regulations are written.
So SCE and PG&E aren't interested in your rooftop. Photovoltaic technology is mature and stable, but the economics and the regulations favor the little guy, you, the residential consumer. PG&E could certainly build distributed generation across all the warehouse roofs through the central valley and power all those HVAC systems without the use of coal, oil, or gas... except no one has come up with a pricing structure that makes it economically feasible for them to do so.
Most of our clients aren't "green." They buy a rooftop solar panel system specifically because they have perceived the financial benefit of controlling their own electricity costs
This sort of leads into timmer's query about having power when the power goes out. Short answer? Yes, you can have a battery system to store your electricity. Long answer? 20 years ago they were relatively cheap. A grid-intertied, battery back-up system that could power your house all night long when the utility shuts down pretty much starts at $100,000. You're better off with a back-up generator for a few thousand bucks. Size it to what you really need to keep running (the refrigerator, a TV, a couple of lights, and perhaps the wine cellar) and just be ready to plug it in.
I really like Steve's whole-circle thinking around energy use that includes the car. A PV system sized to provide power for a car should still be tied to the grid, though, and here's why: the car charges at night, when the grid has tons of unused capacity. The solar panels put power into the grid during peak day usage, when the demand is high. This makes it a win-win situation for everyone. In the future when legislation about load-balancing gets enacted, early adopters could see good rewards.
I know there's a huge pent-up desire to stick it to the utilities and take back our energy independence. But if we can simmer down a bit from there, we can see that real freedom isn't cutting off our nose to spite our face. It's letting the utlitity do some of the job, while taking back some of the job ourselves. This includes making some changes at the policy level, but it also includes getting control of your own energy costs through conservation and generation.