Hi,
plasmas require a s****tload of power.
Lets assume a cut current of 50A and an arc voltage of 100VDC.
The power of the arc is 50 x 100=5000W or 5kW.
If the plasma machine is an inverter style it may well have a power factor of 0.7 or less so the load on the supply is going to be:
5000 / 0.7 =7142W or 7kW.
You'll need on hell of an off-grid supply and a load of storage to run a plasma of any description.
Craig