They have already done work for us.
Not a quotation, not a conversation at a trade show. Work completed, paid for and lived with. That includes work on our own properties, because the fastest way to learn how somebody operates is to be their customer.
We have seen them outside renewables.
Most of our partners came to us through ordinary work: electrical installations, plumbing, heating, maintenance. That matters more than it sounds. Anyone can look competent on a straightforward job. What we are actually judging is how somebody behaves when a job goes wrong, when something is found behind a wall, or when the honest answer costs them money.
Their credentials are checked on the public register, not taken on trust.
Companies House, TrustMark and the MCS register are all public and free. We look, we record the number and the date we looked, and we look again periodically. If a certificate lapses or its scope changes, the reference on this site changes with it.
We are willing to be asked about them afterwards.
The test we apply is simple. If this went badly, would we be comfortable explaining to you why we suggested them? Where the answer is anything other than yes, they are not on this page.