Raining inside workshop
It sounds like your roof has failed. Unfortunately, if that's the case, there isn't anything that can be done inside the structure. The water will always have to go somewhere. Short of building a second ceiling inside, you're stuck.

I'd say call in a roofer to take a look, they'll know the warning signs and can tell you if it's a repair or a replacement kind of job. Might be a couple tiles have broken, or a problem with the roofing underlay (tar paper or similar).

You may be in luck though, that plastic (I'm guessing) roofing tile may be removable/patchable without being destroyed, which would make the roofer's job much easier.

There is a very small chance that this is internal condensations collecting on the new panels, or just above them. Did it do this before you installed the panels?