I believe we have what was the standard fitment in 2004 under the nav tablke rhs cupboard.
Mastervolt 24/500....ie 500W...doesn't run much except laptop, phone chargers etc
I installed a 1500W inverter I bought on the internet and installed it in the locker above the galley and use it to power small kitchen appliances and my espresso machine (that was the real reason for it!).
It is actually electrically much less noisy than the Mastervolt unit.
I know others have even larger units in the engine room