How do you find an electrician who knows home battery installs?

I'm getting an Anker Solarbank 4 Pro when it lands and am trying to sort out the install now.

I've seen a few setups on here and YouTube where people had an electrician wire these in for around £200, so I assumed finding someone locally wouldn't be too difficult. Turns out it is.

The electricians I've called so far either mainly do normal domestic work or EV chargers and haven't worked with battery storage. The solar installers I've spoken to seem more interested in quoting for a full MCS solar install rather than just doing the battery.

For anyone who's had one installed, how did you actually find the electrician? Is there a particular register or certification I should be looking for beyond Part P?

Ideally I'd rather find someone who has done a few of these already rather than being their first attempt.