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Possible first project: Off Grid Water Heater
#1
I have a couple acres of property in Great Lakes area and have been thinking about possibility to add solar for purpose of using the land to support cattle grazing in winter

There is no electricity currently to support an electric fence or water heater for winter

A basic 5gal bucket heater is arround 1000w

https://www.hurricanewindpower.com/dc-water-heating/

A solar fence looks to be basic with one panel given intermittent use to charge a battery

https://www.motherearthnews.com/homestea...0z17aszmul

"When selecting a solar panel to keep your energizer battery charged, make sure it’s rated for 12-volt charging. Typically, the nameplate will list a 21-volt DC open-circuit voltage and a 17-volt charging voltage. A solar panel rated at 6 to 10 watts should be able to maintain the battery for an energizer rated at 0.3 to 0.5 joule, while a solar panel rated at 12 to 20 watts should be able to maintain the battery for an energizer rated at 1 to 2 joules. Which you choose will ultimately depend on the size of your fenced area, your climate conditions, and your latitude."

If I only need the heater to be on 3-4 hrs durring day I could use the solar the rest of day to charge up the battery in anticipation of usage for the heater

So my question is what would be the size of such a system as I imagine it would need to be much larger then the one foe fence system

Tks
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#2
I bought/installed a standard 50gal Rheem hybrid water heater last May. It has selectable modes - one of which is 100% heat-pump heating. In this mode, it tops out at 400watts (240v@1.7a) - e.g. very light on my inverter. We a family of 2 with normal showers, laundry and we have 400ft of hot water circulation - for instant hot water at the taps - e.g. probably 20% of power is wasted toward that. Finally, I have the temp elevated to 125 (instead of standard 120) - its settable.

So far we've consumed an average of 161kwh/month to run this. That's a little over 5kwh/day. Most likely 1kwh/day going to hot water circulation. I think with judicious use this could come down to down to 2-3kwh/day range. The installation is in unheated/under-house where temps go down to 45F (7C) for 3 months of year and max is 75F in summer. So it you have a hot attic install - you might get even better performance.

I bring this up because its a simple, buy-off-the-shelf at Home Depot solution to heat water that seems as 'efficient' as these fool-around with custom heating element systems.

In any case - good luck on your project.
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#3
One thing you might look at if using for supplying a shower is heat recovery from the waste water to pre-heat the cold water.
Eg catch the waste water in a bucket before final drain, & put a few copper coils in the bucket & run the cold inlet through them.
Korishan likes this post
Running off solar, DIY & electronics fan :-)
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#4
Good idea. The other option is to have a copper pipe inside of the drain pipe. As the warmed water flows over the copper pipe it pre-heats the water. You'd want the copper pipe laying on the "bottom" of the drain pipe to get maximum contact, of course. At least 8Ft (2.5m) length would be needed to reclaim enough to make it worth it.
A coil inside the drain pipe wouldn't be good as the coils could catch human debris, like hair and oils, and eventually clog up the works.

This is a project I planned for myself as well.
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#5
(01-11-2020, 06:10 PM)Chablis_m Wrote: I have a couple acres of property in Great Lakes area and have been thinking about possibility to add solar for purpose of using the land to support cattle grazing in winter

If I only need the heater to be on 3-4 hrs durring day I could use the solar the rest of day to charge up the battery in anticipation of usage for the heater

So my question is what would be the size of such a system as I imagine it would need to be much larger then the one foe fence system

Tks


I can answer the fence part. It's nothing to an electric fence. A car battery can run a 12V electric fence for weeks. That's without solar. You spend more time making sure the fence isn't tangling with weeds than just worrying about the battery. A small solar panel is all that's needed to keep it running but I find changing the batteries is easier, had some solar fence types in the past and somehow the solar part always fails.

The water part is another ball game. If you're thinking of keeping a water trough from freezing, then it's going to be a lot of power, 100x more than the fence. Heating up a tank of water is no joke, and a cow can drink a lot. So it comes down to size and location and outside temp. Watch some youtube videos to see what kind of wattage heaters you'd need to keep the water from freezing.

https://www.youtube.com/watch?v=O1NNdov_iDY

https://www.amazon.com/Livestock-Water-T...nk+Heaters
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#6
For keeping the water from freezing, only needs enough heat to keep it above 32F. Field/wild animals will drink water that is that cold w/o issues. And some will even break the ice on top to get to the liquid water below.
Another option, and maybe easier/cheaper/less-power would be to have a fountain in the trough. This would cause enough turbulence to keep the surface of the water from freezing. Granted, it would need to bubble quite a bit, but would use a lot less power than a heater.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
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