I have a very small solar setup, 300 watts of panels and a deep cycle battery. I keep it charged up for emergency use and for a hobby. Gonna try to put one of those S9 space heaters on one and see what it does. Probably need to put a few more panels on that thing. But something to try.
More than a single panel for 300watts? when did you buy those? the lowest I see nowadays where I live is 300w per panel, up to 500w, running the space heater version of S9 might do, let's say it needs 300wh so that's 7200w per day, depending on where you live, say you get 5 hours of sunlight ,so all you need from the backup batteries would be 5700w per day, in batteries' language that's more like 5700*2 = 11400w since you can't really discharge a battery with more than 50% DOD, say your system is 12v so that will be 950ampH batteries, well, worse than I thought
. I think 950ah will cost you about 1k, say with you get an average quality battery with 1500 cycles at 50% dod, you are looking at about 4 years of running that S9 on batteries and solar alone, provided of course you have enough solar to charge the batteries to 100% in those 4-5 hours of sunlight.