Choosing a Solar Provider: Competing Bids
Before you even choose a solar provider, you may have to choose among a number of providers' bids. Deciding on the one you want is not nearly as simple as choosing the lowest bid. Often, the lowest bid will give you the worst job. Other times, the lowest bid only means there are hidden costs. Cautionary advice that applies to other purchases also applies to solar.
Be sure that you are not comparing apples to oranges. For example, be sure that all bidders know exactly what you want: Have they given you a quote for a roof-mounted system vs. a ground or pole-mounted system?
What grade or output are they offering? As you can read elsewhere on this site, there are very different kinds of solar cells resulting in different types of PV modules.
You might really only care about the output of the system which is measured in watts or kilowatts. This should be clearly stated in all bids.
Does the bid include everything you need? If you want a system that is immediately usable, be sure that is explicitly stated in all bids. Some factors that you may want to be sure are included are: all hardware costs, grid connection, permits, warranty, electrical inspection and taxes.
If you are willing to do some final touches yourself (e.g. wiring, if you are qualified) then you may get a break from some bidders. Just be cautious: many manufacturers consider the product warranty void unless the product has been installed by a certified technician. This applies to some solar panels and inverters.
Knowledge is power
Learn all you can about state and federal licensing, certification standards and labeling.
For solar thermal systems, there is a nonprofit organization called the Solar Rating and Certification Corporation. They provide clear benchmarks for comparing solar thermal systems.