offgrid Rod

Hi, I hope someone can help with my offgrid technical issue? Spec: 3kw panels in series into photonic universe 5kv charger/ inverter. 48v 24kv battery bank, 24x 2v cells. Issue: when I'm away and there's no sun for a few days, I lose power. As I'm not there to start backup generator. Solution 1: get a generator with ATS, but this only starts when there is power loss, so heating, alarm and cameras lose power. And once power is restored the generator turns off. I could put a delay relay say for 1-2 hours to get decent charge. But still the issue of losing power in the first place. What I am looking for is a voltage monitor say set to 46v, 47v that'll switch the ATS via the delay relay to start the generator and run for 1-2 hours, so power is not lost. So system is now fully automated. Is there such a unit on the market, as I can't be the only one with this issue. Any help would be appreciated. Cheers.