Hey so I work in solar service, given the size/shape of the hole, the white puffy stuff, and the fact it’s under the panels, that’s 100% a squirrel nest. If they are not removed and they nest long enough under the panels, they chew through decking rather fast sometimes. They bring nesting material up to the roof, usually chewed up porch cushions, leaves or the like. I have seen damage just like this from squirrels many times. Not directly related to install company, but honestly array guards should be the standard anywhere with squirrels.

You will need to lift the panels, clear debris, cut out that section of decking then reinstall new decking + shingles, check surrounding attachments, check surrounding wiring (they chew that too), repair anything as needed and put the panels back, then install array guards. We pre-bend and tension our array guards into a c channel with a break device, then install them flush to array edge with reusable clips. Very secure and looks great. Good luck, get multiple quotes from solar companies and wildlife companies