Getting solar panels in Seattle always seemed to me like a bad idea given the fact that our energy rates are so low and our cloud cover is so high. I figured it would take centuries to pay off the panels. But, with new state incentives and net metering, some systems are quicker to pay off than others.
Based on some preliminary quotes we've received, one of the systems we are looking at could be paid off in 9 years which means that, in about 10 years, everything we generate is gravy. One hitch is that, since we live in an urban area, most systems that are installed don't include a battery bank. Which also means that if there's a power outage and the panels aren't generating electricity, we aren't getting any.
For the nitty gritty breakdown on the three different systems we were quoted and their costs, see my solar panel quote post. In spite of the incentives, things in Washington aren't quite the same as the incentives offered in California. For the same net cost after tax and credits, my brother, who lives in San Jose, had installed almost 3,000 more kWh/yr capacity. So, while he can cover about 95% of his electricity usage, ours would be more like 41% for the same price and time to pay off.