one thing to be sure is the battery Discharge Amps, I have a 3kw cold room that trips the DC side of the 12kw Sunsynk inverter every time the compressor starts up. I believe its a limitation in the battery I have, it is MAX 200A. I am hoping a second battery with bigger fuse and cables will get me over this issue.....
BTW I have been told you cant get VFD or soft start for smaller cold room compressors as they are sealed.