using 400 watt solar kit w/ extra battery I already have....

Not quite--the 1500w inverter will need more of a battery bank to be able to run anything. Usually need four batteries to run a big inverter that runs bigger things like microwave, toaster, kettle.

Solar doesn't work at night and won't supply the inverter directly by day either. It just slowly resupplies the battery bank after the inverter runs it down.