I'm afraid I don't have the exact numbers anymore, but I determined that the 2700W solar panel array installed on my Seattle house for about $14k in 2013 (including a new breaker panel) had paid for itself before the end of 2019. The system worked really well.

People often think that solar won't work well in Seattle because it's cloudy so often, but light still comes in through the overcast, and solar panels don't care which angle the photons hit them from. Meanwhile, lower ambient temperatures mean the panels work more efficiently.