Electric Hot Water Heater

Bones

New Member
Joined
Dec 15, 2020
Messages
1
Hello ALL. Thanks in advance for any advice or suggestions. Building my bus conversion by myself. I'm well versed in EVERYTHING but SOLAR and POWER. We will NOT be living in our conversion year round. 2-3 week trips for the first 4-5 years, then maybe become snowbirds for winter. I'd like to build my power and solar system with that in mind, hopefully not having to upgrade it down the road. Just returned my RENOGY inverter/panel kit I bought on Amazon after viewing Wil's All in One video on YouTube. Simplicity and less wiring sounds great. I cannot figure and or decide upon whether to go with a 12volt or 24volt system. The only area that is of concern is our Hot Water Heater. We would rather not use Propane. My wife is nervous about it and I'm not going to argue with her. I know its safe, but a happy wife is a happy life. We'd like to use a Bosch 2 gallon heater, electric obviously. What is the best system for this? The only other large pull on the system would be an induction cook top. Please help.....
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,353
With an inverter, you can directly power an electric water heater using AC. Ideally that is done only with surplus power after battery charged. Is a state of charge signal available from either the charge controller or inverter? Mine has two SoC levels which are programmable (e.g. at 70% DoD and 20% DoD) and relays they can control.

With two large heating loads (cooktop and water heater), would be good to wire a signal from the cooktop that interrupts water heater, reducing peak demand. The reverse would be easier since we know there is an electromechanical thermostat in water heater, but if cooktop has a switched power or control connection inside, use that to turn off water heater.

If the water heater is used as a "dump load" for excess power, likely temperature will be variable. You can install a tempering valve which blends hot with cold, delivering a constant safe temperature. You can then crank up the thermostat, storing more energy in the tank. For instance 160F at the tank, blended to 110F in the pipes.

2 gallons is tiny. "Bus" sounds large. I had an 18' trailer and I put in a 6 gallon water heater.

There are 120V heating elements. There are 240V elements, which if powered with 120V will be 1/4 of the rated wattage.

While water heater could be made to work with a couple hundred watts, induction cooktop is likely a major load. Probably 24V not 12V is the way to go. That way, 2000W is 80A not 160A draw, easier to wire.

Being able to tilt your PV panels will make significant increase in power during winter (and clear days, flat is better for cloudy). Tilting two directions for morning and afternoon sun will spread power out over more hours.
 
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