Definitely get bird proofing during installation. We didn’t and had no issues for a couple of years, but then one pair of pigeons started trying to nest. I spent the season removing their attempts at building a nest. The next season a bunch of pairs turned up with the same idea, and one pair managed to build a nest where I couldn’t reach it. Fortunately, it was precarious and the wind/rain wiped it out. Cost us around £1k to fit bird proofing as we had to get scaffolding put up due to the nature of the roof.
And get decent bird proofing, not just some flimsy mesh, as they can sometimes break through, and then you have a real issue. There’s a house nearby where the mesh hasn’t held and it’s a full on pigeon hotel. The mesh has actually provided them more protection, making it even more appealing. We’ve got galvanised steel mesh, which even I’d struggle to get through!
Just get air rifle
Sorry, another solar one but I know quite a few folk on here have PV etc and I will get some sensible answers.
I have a fairly large E/W dual array being installed in October and the issue of bird protection has just cropped up. I'd pretty much dismissed it but there's a guy down the road from us having issues with nesting pigeons beneath his panels. You can actually hear and see the activity as you walk past. On closer inspection I can see around 50% of the installations around us have bird protection and now I look more closely, lots of pigeons about!
It's not cheap but I guess better to do it during the install rather than later. What is your experience with/without bird protection on your PV arrays please? I'm looking at a grand or so to add it I think, so not trivial.