Best-reviewed solar companies in Massachusetts

How this list is ordered, and what it is not

By the share of Google reviewers who gave one or two stars — discounted for how much evidence there is behind it, so a long clean record beats a short one. That is an ordering of review records, not of workmanship: nobody here has inspected an installation, checked a licence, or spoken to a customer. A company can have a clean record and still be wrong for your roof.

A company appears only if it is one Google files as an installation business, Google publishes a star breakdown for it, that breakdown covers at least 25 rated reviews — a perfect record over four reviews is noise, not evidence — and someone has reviewed it inside the last 2 years, because a company nobody has reviewed since then may no longer be trading. Fail any one of those and the company is left off this page, never off the site: it stays on the Massachusetts listing with everything we hold on it.

Two details worth knowing. Panel-cleaning, repair and equipment businesses are ranked nowhere on this site, though they are listed on it: a panel wash costs a hundred dollars and almost never goes wrong, an installation costs twenty thousand and carries a twenty-five year warranty, and putting their review records in one order would flatter the wrong trade. And the order uses the upper end of the 95% confidence interval on the share rather than the bare percentage, so a spotless twenty-five reviews does not outrank a near-spotless six hundred — both figures are on every row, so you can check it.