I weigh plusses and minuses.
With solar connected for storage almost zero is gained or benefitted in this scenario. Infintsimal because of perfect storage temperature for AGM self-loss. Ridiculously small.
While solar controllers, the good ones are pretty reliable they are far from perfect. With no one to supervise, why leave it connected? California, Florida, Arizona or down here definitely leave it connected but check the monitor weekly or even more often. Do you feel lucky? Two ways for a controller to fail. On is to lose float reference and charge at higher voltage. The other way is to fail altogether and start consuming battery power. Is either likely? No IMHO. But it can happen. And the risk/benefit ratio is absolutely not worth it. The storage temp is the key. Those batteries would love it at -20c disconnected. They would do fine at -30c. Cold acid is defanged acid corrosion wise.k
