Heating water via solar

[IamJerryP]

Anybody done this on the roof of their RV.
Putting a black container on the roof, or perhaps using the solar heaters tubes for pools.
A black hose on the ground in the summer gets pretty hot, and takes a while to cool. So it seems that if you had 10-12 gallons, or more, in a low profile black container, It would heat fairly quickly. Seems like it would be a cheap way to heat water for boon docking, or when traveling, during summer, and last a little while into the night.

[JFNM]

Originally Posted by IamJerryP

Anybody done this on the roof of their RV.
Putting a black container on the roof, or perhaps using the solar heaters tubes for pools.

Hi Jerry,

I did this for my hot tub at home (S&B). It certainly works but is a pain (leaks and maintenance). On an RV, I think weight way up high might be a problem - could always drain before moving.

I documented some of my solar powered hot tub experiment here. I don't think I noted that I also tried that same black tubing just coiled up on the roof of my garage (with the collector panel). That worked too, can't remember the exact water temp at the output but seems like it was in the 130 degree range. I think I paid about $100 for the pump, controller, and temp sensors.

Since our RV hot water tanks are small, seems like a very small "solar heater" would be sufficient along with a small solar powered electric pump to lift the water (and associated temp sensors and pump controller).

[Tony Lee]

Many have thought about it but then the practicalities get in the way.

Hot water consumption in a RV is much lower than in a house and is readily and conveniently supplied by a standard RV HWS powered by propane.
Some models are also fitted with an engine-assist heating coil so when you arrive at your destination the HWS is already full of hot water.

Also possible if you have an oversized solar system is to use energy once the batteries are charged to heat the water via an inverter and a mains element.
(using power from the engine alternator is definitely NOT a green solution)

[oatmeal]

Well, this isn't cheap, but here's a kit for doing something similar to what you're suggesting: RV SOLAR HOT WATER KIT - BHAsolar

I don't know anything about it, but I'm intrigued.

Tony Lee mentioned people with oversized solar arrays. We're one of them (1,050 Watts) and we rewired the water heater to run through the inverter. There was some messing around with the settings on the solar controller and installation of a solid state relay, but the upshot is that once the batteries are full, the excess solar gets diverted to the water heater.

Once the batteries are in float mode, I flip the switch for the electric water heater. The water heater comes on if the battery voltage is above a certain point. Of course, once the water heater comes on the voltage drops, so the water heater goes back off but if it's sunny, the battery voltage recovers almost instantly, so the water heater comes back on. Many times a second.

It's not only free, but it uses up solar production that would otherwise be "wasted." I think it's great.

[IamJerryP]

Originally Posted by oatmeal

Well, this isn't cheap, but here's a kit for doing something similar to what you're suggesting: RV SOLAR HOT WATER KIT - BHAsolar

I don't know anything about it, but I'm intrigued.

Tony Lee mentioned people with oversized solar arrays. We're one of them (1,050 Watts) and we rewired the water heater to run through the inverter. There was some messing around with the settings on the solar controller and installation of a solid state relay, but the upshot is that once the batteries are full, the excess solar gets diverted to the water heater.

Once the batteries are in float mode, I flip the switch for the electric water heater. The water heater comes on if the battery voltage is above a certain point. Of course, once the water heater comes on the voltage drops, so the water heater goes back off but if it's sunny, the battery voltage recovers almost instantly, so the water heater comes back on. Many times a second.

It's not only free, but it uses up solar production that would otherwise be "wasted." I think it's great.

Exactly what I was wondering about

[Gocoffeer]

Jerry... the diversion method of using the solar array to power other projects is not difficult...but it is a bit on the costly side. I am deep into my solar project and have been molding and meddling with the inverters at this point. VSHEETS had made a solid designed solar system for his rig and published the design. I used his basic thoughts and designed mostly a similar install for my rig. I discovered thru the project that there is a huge budget bloom contributed by accessories needed for installation. Copper wiring (WOW...it is costly), conduit and boxes and fittings, tools I did not have (crimpers and wire ends) and the host of items related to the battery (custom cabling and connections to the battery added up) I am in the phase where I am maximizing what the RV can do with the batteries and power produced. I have 3 each inverters. 2 are already installed (300w Triplite models) These run the TV electronics and some independently installed outlets up front for small and light use charging and laptop use. I also have a 1000 w Pure Sine not yet tied into its respective newly installed circuits. This will run...refrig and microwave. That will basically get my needs off the generator and or shore power for most use. I can turn on and off the various inverters as I see fit... During all of the project I was looking over at costs and add-ons. Wanted to decide what was practical to run on solar and play set and forget... Hot water? Hmmmmm I do not think in my case hot water would make me feel I was getting more out of the project than I was spending. I have a propane water heater...a new water heater would need be installed and then the appropriate inverter and the wiring. When you see how much welding cable used to hook up an inverter costs ... OUCH.....