inverter 10000w
a good sense efficiency for this inverter would be ~ 80%. that's about 520A at 12 current draw, and even more at lower voltages.
it isn't practical for this power level to be supplied with 12V. most of the inverters which are >3000W are powered from 48V or more. of course, in special cases, can be powered from this voltage too. think about that the electrical resistance of the cables, connectors, and screws is higher that the total Rds ON of the paralleled MOS-FET's. so you might loose more power on the connections than on the power stage.
off topic:
few years back i had to make a challanging project. an inverter which supply a house with 230V AC rated at 2KW and supplied at 2V only !!! from a huge telecom battery rated at 2400Ah. it was for a friend, which got this battery from an old telecom site which was upgraded. i made the step-up spms with 10 push-pull transformers, all inputs in parallel and outputs in parallel, each rated at 225W, and the primary current was about 96A to 125A depending on the battery charging state. the bus voltage was 380V, and a full bridge power stage generate 230V AC. the reson for using 10 step-up stages was not only the reduced current handling compared with single one, but.... at 2V in, 2KW and 30KHz, on any ferrite core need between 0.2 and 0.5 primary turns which is not achievable. but at 225W can make 2x1 turns for push-pull without problems. i used 120 pcs. vishay's 20V DS MOS-FET with 2 mR Rds ON, and 80A drain current.
problably the most interesting part was the battery charger circuit...