there are literally tons of ups inverters out there awaiting repurposing that are 24volt buss units
APC has several models up to about 2kva that are 24volts
they make several that are pure sine wave, or at least very clean sine wave
efficiency is about 85% or so, which isn't fantastic, but the price is right as
they can be had for little or nothing.
downside is the pull 10s of watts idleing so you probably would want to shut them off when not needed.
for experimental purposes, there is a lot to be said for the use of one or more such units.
replace the batteries with higher amp/hr units and the surge capacity becomes respectable as well.
bob g