How to reduce maximum power rating of dishwasher for use with photovoltaics inverter?
From an efficiency standpoint you would be way better off to use the sun to heat the water up instead of converting to electricity in the middle of the process. Modify the dishwasher to accept the solar heated water instead of dumping any electricity into the heater coil.

To get even more efficient adopt a washing strategy with cold water cleaning in a basin followed by drying in the sun.