I'm not an electrician, but from what I can tell checking forums stats and even Google search terms related to Solar PV, it appears the industry in the UK has died off bigtime.
The government stopped subsidising it, or something, so it's now just expanding at a normal rate. So the jobs shared between those who got some experience and / or training a few years ago (which was a lot of people all chasing the gold rush as it were) isn't much at all per head now.
I notice you're currently in Iran though (according to your flag by your avatar) so I don't know whether you're asking about the UK, or Iran, or just globally generally.