To be honest, with the exception of Segen, none of the wholesalers I have approached recently have asked for any credentials to prove I was in the trade.
That said, it's no different in any other trade,so why would solar be any different?
This is why installers are better off working together and keeping the prices tight so that the market moves as a whole rather than the smaller or 'fly by nights' don't push the FiTs down prematurely. I'm not saying there shouldn't be any competition, but being able to whack a job in for £1000+ less just seems insane and it's very short sited in my opinion.
I'm just starting out in this game and I can see what a minefield it is. Unfortunately the other aspects of my business will to a certain degree, revolve around the RHI which will be the same story I guess. Might be better off doing the night shift in tesco's in hindsight..