"It lets my cattle enjoy a nice, warm drink of water even on the coldest days," says Roger Brown, Walker, Kan., about the solar-powered system he uses to heat his 400-gal. stock tank. It has a unique control heating tube that stays open all winter.

"The key to this system is that I'm only heating 10 to 15 gal. of water at a time," says Brown, noting that the system costs just pennies a day to operate.

The system is "powered" by a 4 by 8-ft. solar panel that sets just outside the tank. A small pump circulates antifreeze from the solar panel to the tank.

A length of 12-in. dia. pvc pipe with a copper heating coil inside it runs from the surface of the water, down to within a couple inches of the bottom of the tank. A pair of hoses run from the heating coil to the solar panel. As the animals drink, water is drawn into the pipe from the rest of the tank.

"In cold weather, the water inside the pvc pipe is generally 20 to 40 degrees warmer than the water in the rest of the tank," says Brown. "On a cold morning when there's ice on the rest of the tank, the heating element will keep the water inside the pvc pipe from freezing. If it's very cold, a little ice might form inside the pipe. But if the sun is shining, by 9 a.m. the ice will have already melted inside the pipe. Then as the day gets warmer, the ice on the rest of the tank will melt. If it's a cloudy day I just turn a valve to shut the water off.

"The 110-volt pump draws only 1/2 amp. It moves a very small amount of water but that's just enough to keep hot water pushing through the coil and back to the solar panel."

Brown says the system didn't cost much to put together. "I paid for the pump. I already had the heating element coil and the pvc pipe, and I got the solar panel free from someone who had been using it on his house but no longer needed it. My only other cost was for copper fittings, hoses and antifreeze," he notes.