Hot water heater-off grid

[Bluedog225]

Well, here we go.

I have only dipped my toe into the solar hot water world. Enough to know that solar electric hot water is too much trouble and too inefficient for me.

So I’m building a direct solar water heater. Trying to to this on the cheap as possible and with a little mad max style.

I’ve got a west facing concrete wall below the kitchen that gets full Texas sun. The plan is to use 3/4 pex A and coil it inside this 36”x36” galvanized drip pan, paint it black, and cover (with spacer) with a big piece of tempered glass. I got the drip pan and a great piece of 1/4 tempered glass today for a song.

I’ll make a frame out of 2x2 angle iron so I will have something to mount to the concrete wall.

For the hot water container in the kitchen above, I will find a stainless steel box I can tap into for the hot water to circulate and to dispense.

I don’t think I’m smart or ambitious to pull off a heat exchange. But maybe.

More pics as this develops. Any tips welcome.

 

[efficientPV]

"a little mad max style" Maybe, I remember watching those movies and wondering why, in a world where petrol was so precious, all the vehicles got less than 5mpg. For me PV heating is really cheap and easy. Some day this will be true for everyone.

 

[Wellbuilt]

I have a buddy that heat his water in a 150 long black well line .
The line runs on top of fence 75’ down and back .
It plumed into his gas water heater he has a small solar pump that moves water when the sun is out .
It works good and supply’s all his hot water from may to October .
The system gets drawing for the winter

 

[circus]

Prior attempt

 

[Rednecktek]

I remember growing up my dad made a solar water heater that lived in the side yard. I didn't know what it was at the time (almost 40 years ago now!) but nowadays it seems so simple.

Old hot water tank stripped of its shell and spray painted flat black.
Big plywood box.
Mylar coated 2" foam cradle it sat in
Big sheet of plexi on top.

Yeah, that was super simple!

 

[The Dish Doc]

Be sure to incorporate a way to drain it in the event of a hard freeze. My buddy has full solar on his house and a hot water panel also and when his re-circulating pump failed the copper pipes froze in the unit and busted.

 

[Bluedog225]

good point. I’ve been thinking about that. It gets more complicated.

 

[Externet]

Good day.
Visited a friend in Florida last year and found him making a plywood tray with a glass cover taken from a defunct sliding door and he was ready to make a serpent of PVC pipes in it to be painted black, and sealing the tray with silicone to put on his roof.
Somehow I convinced him to change his ideas and I built for him this spiral that I saw on the web years ago :

----> https://www.treehugger.com/how-make-simple-solar-spa-heater-your-roof-4859242

Took a couple of hours to make and secure on roof. Connected one end of the coil to mains water supply and its other end to the electric water heater inlet at his house. Has been a total success for very low cost and reported a reduction in his electric bill.
I suggest you consider this. For a colder location/season, it may be covered by clear plastic or modified to suit.

Now he wants me to visit again to install photovoltaics...

 

[OzSolar]

A batch water heater is ideal for non freezing climates.

However most of them don't make it more than a few years in freezing climates as owners eventually fail to drain them before the first hard freeze.

For freezing climates I'm pretty sure you could heat your water with PV powered electricity for less money and hassle than a solar hot water panel, heat exchanger, antifreeze, pumps and controller, etc needed for a solar hot water system.

You might need to step your water heater element down to 2000 watts or less plus put it on a timer so it's not competing with other loads on your inverter but in the long term I suspect most folks will be happier with the simplicity and use of standard gear that will be far easier to maintain.

 

[Rednecktek]

I remember growing up as a kid my dad took the inner tank out of a hot water heater and mounted it in a box lined with the foil covered foam and a plexiglass lid. It lived in the yard. I never knew why until about 30 years later.

 

[GLC]

"I have only dipped my toe into the solar hot water world. Enough to know that solar electric hot water is too much trouble and too inefficient for me."

I don't know why people say this. Anytime you can get 150 degrees by 3 in the afternoon in a 50 gallon hot water heater tank I think you are doing pretty good especially since it is drawn directly from PV cells.