Then there is the option to run the engine until it heats up the water in the water heater. Running the engine for warm water is inefficient and undesirable.
Now we have what promises to be a pretty good solution; solar heated water. Because the solar panel is dark in color, it absorbs a significant amount of the sun's energy in the form of heat. This is dissipated through the back and front of the panel by air currents. By attaching a heat collector/exchanger to the back of the panel, properly insulating it and circulating water through the heat exchanger we are able to collect that excess heat and store it in the water heater tank or in a separate holding tank. While still in the test stages, we have completed proof of concept and can make the heat exchangers available to DIY mariners who are interested in setting up such a system. We plan on offering a complete water heating system retro fit kit within the next year.
Initial tests indicate that with our 140 and 160 watt systems we can heat 3 gallons of water from 60 to 110 degrees F in less that a half hour on a sunny day with the ambient temperature of 65 degrees F.
Our top-of-pole system is about to be a 3 in 1 assembly; solar panel mount, outboard motor crane and solar water heating system. Call us if you are interested in participating in our test program.