Actually is is better to use 220V if the heater allows for it. Having a higher voltage actually lowers your current draw (amps) if the wattage and resistance are the same in both heaters. Also, using 220V instead of 110V actually can help to keep your panel current draw (amps) even on each line.

It would be cheaper running 110V with 220V heater

But possibly wont work if you intend to use the max power

If the wattage = constant

Current is much higher on lower voltage compared to higher voltage supply , to produce

the same amount of power ( watts ).

But possibly wont work if you intend to use the max power

If the wattage = constant

Current is much higher on lower voltage compared to higher voltage supply , to produce

the same amount of power ( watts ).