Your maximum current is too conservative, power transmission calculations are conservative enough to run wire through fiberglass insulation in a hot attic. Clos

Your maximum current is too conservative, power transmission calculations are conservative enough to run wire through fiberglass insulation in a hot attic. Closer is "chassis wiring" which rates that wire for 0.47A: https://www.powerstream.com/Wire_Size.htm https://www.powerstream.com/Wire_Size.htm To deliver 150W with output voltage of 300V (0.5A) would require an input voltage of 640V at an efficiency of ~45%. Not great. The water could handle a lot higher heat distribution but efficiency is already terrible. > For maximum power transfer at a fixed input voltage.