I’m hoping the attached is a common entry pre-installed at the factory. My question is, is this water tight when the cover is removed to get to the MC4 connectors or do I need to cover with a gang box?
Hard to say, but it appears to be purpose built for it. MC4 connectors are water tight by definition, so when the cables are installed, I would say it's waterproof... assuming the rest of the unit is designed for it.
