I see where you can skip the invert-charger combo and get a dedicated unit from these guys for under $200. Get it for your 46V or 48V lithiun-ion battery,Should probably be more efficient too, vs converting the panel to 110V AC and then converting that back to DC,

There are other options available.I am not making a recommendation as I never used one. In particular, select one that won;t exceed the charge current of your battery, usually 2-3 amps,