If you are living off the Grid and looking for a way to heat some water for a shower check out this awesome little Device. It plugs in to the DC socket of your car or a 12 V battery...
RinseKit Hot Rod Water Heater Accessory for Portable Shower ...
Link: https://www.amazon.com/dp/B0788BKKNQ/ref=cm_sw_r_tw_dp_U_x_nbAzCb6EF0BB0
Quickly and safely heats the water in a RinseKit to a comfortable shower temperature with built in timer shut off
• Plugs into a standard 12-volt vehicle accessory socket (cigarette lighter) with an 8" cord long enough to reach to the back of an SUV
• Stainless steel heating probe screws into the drain plug port of the RinseKit and can remain there
• Utilizes a 30, 60, or 90-minute timer option
• Compatible with all RinseKit models