How big of a system are you installing?
For simple "battery maintainer" systems - many indications of actually connecting into the bathroom vent fans - sometimes you can get to the battery without doing a new roof penetration. Better to penetrate the vent.
For "real" solar installations where there is not a penetration - and I don't think that Keystones setup for this on the roof, the few non-Keystone units I've seen with solar options have a plug-in on the side, not the roof... Here's how I would go about doing the roof penetration:
https://www.amazon.com/dp/B0111RNZDY...V4TRU72P&psc=1