i think it is disingenuous to represent that AC is a standard or required by law for a rental anywhere, at least in the US. I do find it shitty that the AC included with the unit is damaged, and land(slum)lord won't fix it, but again, unless it's in the lease there really is no requirement that the LL provide it in US. I think it is good to start a discussion on if AC for a rental should be the law, (edit: i also would strongly support this) but i doubt we will see that become the case, especially in southern states which probably would need it most.
i didn't downvote but 17v on a 12v battery maybe seems a bit high. I'm more used to about 7-14% over (maybe up to 14v on a 12v batt) when charged/floating but i don't use solar anywhere currently, and i usually work on 48v systems. i normally expect to see about 54v on a fully charged battery string (13.5v per battery x4) with the rectifiers running.
i also second the opinion of running an automotive PSU for this situation.
edit: i looked it up since i was curious, some "12v" solar panels can output between 16-20v, but it's recommended that you would use a charge controller, especially if you have lead-acid batteries