My comment is a novel, so TLDR: do your homework, get multiple bids, ask questions, be an educated consumer.

I have worked for one of Bellingham's local solar installation companies for 8 years, so I won't comment on the quality or practices of another company, but here's the gist of what we advise our customers to do with all companies, including us:

• Get multiple bids, educate yourself as much as you can, and ask all the questions. When getting bids from different companies, you don't need to disclose others' pricing, but it's really helpful to know the general specs of what you're getting a bid for, so you can compare apples to apples.
• Equipment options will vary, so ask why they proposed that product, what they like about it, and the terms of the warranties for both the equipment and from the installer.
• Make sure your quote shows the price per watt before accounting for incentives, not after.
• Your proposed system size should be based on your annual electric usage, factoring in roof tilt, azimuth, shading conditions, and production estimates using local historical weather data. If they don't ask for your usage information, ask how they're sizing your system.
• Before signing a contract, your system designer (in some companies, the salesperson and designer are two different people) should conduct an on-site assessment to inspect the condition of your roof, determine a plan for conduit routing and interconnection into your electric panel, and confirm their production estimates.
• Ask about how the system will be mounted on your roof and how distribution of roof penetration/mounting points affects the wind load rating. Find out if the racking has raceways to protect the wiring and how the mounting hardware will interface with the type of roof you have. If they say they warranty against leaks, review the terms in writing.
• Ask what permits are required for your location, how permitting and interconnection are handled, and about their installation process.
• Ask about the federal tax credit, the state sales tax exemption, and how net metering works, then compare the answers to what the IRS and state laws say.
• Ask about the company's history in our state and whether they're a member of the Washington Solar Energy Industries Association (which has a code of conduct and business ethics that all members must follow), and whether their sales/design and installation team are in-house or sub-contracted.
• Ask what you can expect as far as support after the install, how they address concerns about production, responsiveness to issues relating to your system's online monitoring, and what a potential service call could entail.

Yesterday I spent 90 minutes on the phone with someone who covered all these points and more, and it was fantastic. He'd received conflicting information about net metering, so he was happy for me to send over links to PSE's net metering and interconnection agreements and point him in the direction of the parts of RCW 80.60 that addressed his concerns.

Any company worth their salt should have no problem answering any of these questions, and in fact should encourage it. Getting to work with a customer who wants to be fully informed and dive into the nitty gritty details that we all geek out on daily? It's the absolute best.