My Inverter is 1998 technology. It doesn't give me a read on the amperage it takes just to keep it turned on. On my boat, I have a Xantrex MS2000, about 2005 technology. I assume things are improving in inverter efficiency, as I have head of newer units using very little power to stay turned on. My MS2000 does give a readout that shows it uses up to 8 amps of continuous draw, just to keep the inverter turned on. Overnight, (8amps x 8 hours) 64 Amp/hours, all of which needs to be generated and put back in, which will add about 45 minutes generating time just to keep the batteries at the same level.
So I leave mine off unless using a 115v appliance.