a 150 watt panel cost about �400,
so youll need about 50 of these to supply 8000 watt.
but thats all at the same time
but with batteries, and an inverter dependant on what would be the max amount of watts at any one time, but i would guess 5kw would be more than enough at any one time ie: cooker, water heater etc etc
gets quite complicated, firstly you need to work out , how much is constantly used , and the peak, then work out how many batteries you need to supply that for one day, then, work out how many panels would be needed to charge them back up again