Solar, A/C, DC Hot Water Heater Project

[boywonder]

Originally Posted by arctictraveller

Boywonder, If you redo those calcs at something like 13.2 or even 14vdc things will probably look even better.

Yes, true.....

I think 1der took the above voltages into account when deciding on what wattage element he wanted to order.

[1der]

Originally Posted by boywonder

Yes, true.....

I think 1der took the above voltages into account when deciding on what wattage element he wanted to order.

I did. As a matter of fact I had two elements made, one at 12v/200w and one at 12v/240w. Going with the 200w to start since I think that will be closer to optimal with the 300 watt solar panel less draws for refrigeration and float charge for batteries.

[Bbasso]

That water heating system sounds ridiculously complicated compared to mine...
I bet it will work just fine, but why so intricate intricate?

My system for comparison is 21gallows through a filter into the pump then through the eccotemp heater. (On for hot, off for cool)

[1der]

Rob - not really complicated at all. It is an electric water heater with AC and DC Elements, flip a switch. No propane. I wanted something inside for winter and nights and connected to the sink faucet. Also, idea is to utilize the excess solar energy to heat water after the batteries are in float.

I also have an Eccotemp that may get incorporated for summertime outside stuff, probably hang on the storage box.

Where is your Eccotemp located?

[arctictraveller]

Originally Posted by 1der

idea is to utilize the excess solar energy to heat water after the batteries are in float.

Are you planning to manually control when the heater is connected to 12v? (something like Boywonder's drawing?) I'm trying to figure out what will happen if the batteries were low, and the heating element is connected. Also, how do you keep from draining them after the sun goes down, the other loads suddenly exceede the solar output, or it get's cloudy while your on a hike? I guess you could use a voltage sensitive relay of some sort. Anyway, this sounds like a great idea, I'm looking forward to seeing how it all works out.

[Bbasso]

Mine is mounted on the 40 door. I'd like to make a nice multi-use box to hide it in one day.

[boywonder]

Originally Posted by arctictraveller

Are you planning to manually control when the heater is connected to 12v? (something like Boywonder's drawing?) I'm trying to figure out what will happen if the batteries were low, and the heating element is connected. Also, how do you keep from draining them after the sun goes down, the other loads suddenly exceede the solar output, or it get's cloudy while your on a hike? I guess you could use a voltage sensitive relay of some sort. Anyway, this sounds like a great idea, I'm looking forward to seeing how it all works out.

The kid's dump load feature has a zillion settings based on voltage, state of charge, etc.....so it's internal relay will disconnect if things get low.

[Flux]

very nice work gentlemen.

I never intended to have onboard water heating. But after seeing this and also knowing how much excess engine heat I have.........well, it's kind of silly not to.

[Scalf77]

As far a wiring I would suggest two separate circuits, with their own t-stats and circuit protection. I don't expect that the existing breaker would work with DC, also you show both circuits going to ground. In reality they are going through the AC neutral which while this could effectively be grounded to your the frame of the vehicle. This is outside of my basic knowledge but I would think there would be some sort of code violation there. It would also depend on where the ground bonding occurred. When power is coming from the inverter then you would have that bond, when the inverter was off, if plugged in that goes back to the service. In you're practical use case, it would depend on if the ground bonding was left connected for it to work I would think. I may be way off base here, but it is something to think about.

.

This is very cool project.

-greg

[Flux]

Greg brings up a question that kind of had me scratching my head. Really it's just the simple question of grounding a 120V circuit when you have shore power coming in.

I know that the ground and neutral in a 120V circuit all head back to the same bus and earth ground in the breaker panel. But when you bring 120V into the van, are you grounding to the Body/Frame?? Or isolating the ground and letting the GFI handle any shorting that could occur from the hot to the van??

Sorry, seemed like a good time to ask, don't want to be a thread killer.