# Would like to build passive solar stock tank



## naturewoman (Nov 12, 2002)

passive solar de-icing stock tank 

The only ones I've seen advertised are for horses. They are also very expensive. They are a box with a solar panel or window on the south facing side, and a plastic tank set in the top. 

I'm looking for a way to make my own, as I don't have over $400 to buy one. But I bet it's simple enough inside (the solar panel?) that I could do it myself if I just knew how.

Anyone have one who has looked inside to see how they are made? I know how to build the box...it's the solar part I don't know how to do. Does it have to have something inside like black tubes (behind a window) filled with water that circulate through the tub?

Or a link to a site that might explain how to rig up something myself.












> Solar Powered Water Trough
> 
> Holds 25 Gallons and easily refills from your garden hose or water hauling tank!
> 
> ...


----------



## MELOC (Sep 26, 2005)

it is probably just an insulated box painted black. the inside may have aluminum painted black to tranfer the heat to the air more quickly.


----------



## tinknal (May 21, 2004)

A fried of mine had one of these years ago. It was just a steel stock tank (one of the smaller ones, 100 gallon?), with a well insulated wooden box built around it. His was 4 inches thick with fiberglass insulation but if I were to build one I would go 6' with foam insulation. The top had an opening just big enough for a horse to drink out of. The water would stay open (sometimes he had to break an inch or so of ice in the morning) in all but the coldest of Minnesota weather. A big "what if" is how many animals are drinking out of it. The more animals (and quicker the water is replaced), the easier it is to keep open. Good luck.


----------



## highlands (Jul 18, 2004)

We are in northern Vermont. Sub-zero routinely. Sometimes -45Â°F. Two things we do to deal with water being available in the cold of winter:

1) running water - it runs continuously from our spring overflow even in the coldest weather.

2) large mass - we have a 725 gallon tank that never freezes in another place. It has so much thermal mass that even our coldest weather doesn't freeze the water. I did put foil-bubble-bubble foil insulation on the outside and a snow drift on the north west side to buffer it.

I've often thought of doing something with a solar collector on it but have not, yet, since it has not been necessary.

Cheers,

-Walter
Sugar Mountain Farm
in the mountains of Vermont
http://SugarMtnFarm.com/blog/


----------



## SolarGary (Sep 8, 2005)

Hi,

As others, I would guess that its just a dark colored tank inside. This will absorb heat as well as anything. 

Let the sun that comes through the glazing shine right on the tank. 

Insulate the tank everywhere except where the sun shines on it.

I would think about using something like 1/4 inch Lexan (polycarboante) for the glazing, as it will be pretty much horse proof.

The bigger you can make the glazed panel, the more heat it will collect.

Some additional thoughts (may not be practical):
- Lots of the loss will be from the water surfaces, so --1) keep it as small as possible, 2) float a layer of ping-pong balls on the top as insulation. Or, maybe just thin and flexible foam that the animals could push down to get a drink (I said some of these might not be practical 

- Lots of loss out the glazed panel at night. If you visit the tank in the morning and afternoon, then having an insulated lid on the glazing at night would greatly improve the net collected energy over a day -- in cold weather there would probably be a factor of 2 plus more net energy collected by reducing the night losses with an insulated cover. Something like this batch water heater:
http://www.builditsolar.com/Projects/WaterHeating/MSBatch.pdf


If you build this, I'd really like to hear how it comes out.

Gary


----------



## wy_white_wolf (Oct 14, 2004)

SolarGary said:


> ...Lots of the loss will be from the water surfaces...


Around here ranchers throw old tires in thier stock tanks. The black tires help absorb extra solar radiation and cut down surface area. Horses and cattle can easily drink around the tires. If they do freeze the areas around the tires melts first and then you can easily move the tire over a little to open up a drinking hole.


----------



## Runners (Nov 6, 2003)

Don't paint the inside of the tank black... unless you want hot drinking water for the summer.


----------



## hoofinitnorth (Oct 18, 2006)

This was in another forum.

The example of the pre-fab unit costs about $600 from what I've seen but you can build one with a few simple components for less. Whether or not it will work on cloudy/low asthmuth days, is another issue altogether...


----------



## SolarGary (Sep 8, 2005)

Runners said:


> Don't paint the inside of the tank black... unless you want hot drinking water for the summer.


Hi,
I don't think it will work very if the part of the tank that is behind the glazing is not painted black.

You could turn the tank around so the window faces north in the summer, or cover up the glazing??

Gary


----------



## naturewoman (Nov 12, 2002)

Thanks guys...I will try just the insulated box with the window, and black paint on the outside of the tub..it is galvanized, so may not take paint well. I'm using a 17 gallon washtub for two small goats. I have no running water, so I have to carry water up from the creek every day to replace the ice I pull out...which is why I'd like to find a way to preserve as much of the water as possible. I was thinking I'd cover most of the surface of the stock tank with just the front part open to the goats. 

I also thought of floating an inflated motorcycle inner tube in the tub, to keep the ice from freezing to the edges of the tub, so it can be pushed down by the goats to get water...but I'm afraid they will just pull the tube out to play with it, or chew holes in it.

I probably won't be able to test this till next winter, so I doubt I'll remember to post a follow up thread on how it works. I don't have materials to build it now, and it's too wet outside to drag out my tools, so I will do it this summer. This has just been an extremely long cold winter (colder than I remember since I've been here) and my water has been frozen for 26 days now, which is no fun. I hope this works.


----------

