We have a system set up for long term off grid. 300w with 260Ah running a Psw 1500w inverter and 175w with 240Ah for the 12v side. Last winter we were on our pitch in Spain for 6 months hooked up, but used only a tiny amount of power (they charge for it on a meter) and that was probably my over caution regarding battery protection. This year we will see if we can use no hookup.
Cheers
Ed
Cheers
Ed