FWIW, I left an AGM, partially charged battery, to over-winter in unheated space in MN. After 5 months it measured 12.4 V. I know I wasn't doing it any favors and treat my cells a lot better, now, but the amount of puny discharge was surprising.
If I was the OP, I'd look for a single, higher voltage, polycrystalline module. Put it in a space where it gets the most light. Needs change and having some solar is better than no solar. It could be a start to having electric power without hauling fuel and listening to a generator. Having power in remote locations changes everything, the daily schedule isn't infringed by a budget of generator run time. Been there.
FYI, my 235W module is still harvesting power after sunset. not anything appreciable but it is still pushing ma until the sky darkens.