I really don't know how else to do it..sorry I can't help.what about some kind of solar powered device?

I am assuming that the area where you want to site your solar water heater is in the full sun..... I have seen advertised a solar water heater for bird bath type arrangements, one of which was a true solar powered one and the other, as I recall, was a double-walled, heavy black plastic floating cover with a small hole in the middle for the birds to drink out of. The latter covered most of the surface of the waterer, and I think had styrofoam or the equivalent between the plastic layers. I would think you could approximate such, speaking off the top of my head here, using a larger, black-painted, outer container, maybe with an inner lining of styrofoam insulation, or hay/straw, to hold and keep the heat, and the water container itself being either very shallow or quite deep, but narrow, so there's less surface area exposed. I don't know whether burying the outer container part way into the ground would make it warmer or colder. Building a plexi-glass wind-break around it, or siting it on the south side of a building, or piling rocks around it, or making a rock "patio", might help also, limiting the wind-chill and concentrating the solar gain. If that won't keep the water unfrozen, or thaw it out by mid-morning, then you might have to have 2 of the inner containers and continue to bring one fresh with warm water in the AM, letting the insulation keep it thawed during the day. I don't know for sure, but think that if your hens have warm/not-frozen water in the AM and most of the day, they will be OK. They can learn to drink up when the water is available, although I admit it would be better to have water available for most of the day - night isn't so important.

There are propane heaters for water tanks out of reach of electricity. Maybe a search would turn them up. I have heard them discussed for use in the far pastures for sheep. I don't remember how long a tank of propane lasts, seems like the heaters were fairly economical to use.

The horse solar heated tank is pretty expensive. Doesn't hold a lot of quantity. Also the one person I know who owns it, says you have to use Pam spray or vegtable oil on the floating ball cover, to prevent sticking on edges. Horse drinks, usually dribbles water back on tank, which freezes floater to box. Then horse can't drink next time. Oil or spray makes the drips run off faster, before freezing shut.

Greetings,
At my wife's request, I've developed a solar-powered livestock water heater and am considering bringing it to market. Originally installed in CO, it routinely produced 65F water on 20F days. Initial costs were in the $1000 range. I hope to reduce that slightly. This cost would include the water cost of the livestock water tank, the collector and a PV panel for circulation, so the entire unit is self-contained (except for the water!).
Please feel free to contact me at tlampros@verizon.net.
Regards, Tom Lampros

what kind of temps are you dealing with and how much water are you talking about? What kind of and how many animals?

Dave

The original tank was 150 gal, and the system could be designed for larger tanks. We're watering horses. You could use it for cows or others, too. When the outside temps were in the teens/low 20's, the water heated to excess of 60 degrees. This was in CO, land of abuindant sunshine, but it's just a matter of including a big enough collector. I'm experimenting now in NY, land of abundant overcast skies!
The system does use anti-freeze, but in such a way that the animals would bever be exposed to it. Note, too, that this is a water heating system only; it doesn't pump water into the tank. You still have to provide water from an external source.
Cheers, Tom

The original tank was 150 gal, and the system could be designed for larger tanks. We're watering horses. You could use it for cows or others, too. When the outside temps were in the teens/low 20's, the water heated to excess of 60 degrees. This was in CO, land of abuindant sunshine, but it's just a matter of including a big enough collector. I'm experimenting now in NY, land of abundant overcast skies!
The system does use anti-freeze, but in such a way that the animals would bever be exposed to it. Note, too, that this is a water heating system only; it doesn't pump water into the tank. You still have to provide water from an external source.
Cheers, Tom

Tom, what do you use to circulate the water?

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In searching for alternative methods to keep water from freezing in "SUB ZERO" weather I ran across a couple of old time methods told to me by old time ranchers from the mid west. I have not tried them but they sound feasible to me ! Dig a hole or trench, place manure in the bottom, place tires on the manure, add more manure then tires, alternate as you build up until you have tires on the top, (be sure to fill inside the tires), I do not know if the water trough needs to be lower than the top of the ground, I would imagine so but only slightly,

The second method was a surprise to me, get a round 5 or 10 gallon steel oil can, submerge in the center of the tank and weigh down with large "rocks" then fill with any slow burning oil, light it and it will keep the water from freezing for as long as it burns, never could get the actual length of time, and it must be a metal tank, inaccessible to the curious equine nose

My dad was telling me that his dad had a barrel in the stock tank and burned wood in it to keep the water thawed back in the early 1900's.