There are many variables that go into the cost of a solar PV system. Like all major purchases, there are many decisions to make. How big of a system do you want? How efficient of a system are you looking for? What is the quality of equipment you’re purchasing and where was it made? Are there special installation considerations?
PUD 3 is finding that you can expect to spend between $3,000 to $8,000 per installed kilowatt (KW) of designed capacity. PUD 3 recommends getting at least three bids and selecting the contractor you feel the most comfortable with that offers the best product available within your price range. Please see the section of the guide linked above entitled "Working with a Solar Contractor".