Building a Solar Chicken Coop Heater

Can You Make a Homemade Heater that Won’t Burn Down Your Coop?

Building a Solar Chicken Coop Heater

Reading Time: 7 minutes

Do chickens need heat in winter? Is it worth the fire risk? A solar chicken coop heater could solve both problems to keep birds safe when temperatures plummet.

Each autumn, new chicken owners flock my direction when the first fall temperatures hit. Their chickens are cold! Should they put heat lamps or space heaters in the coop?

There are solid reasons to avoid using electric heat within a chicken coop.

  • Fire danger is the biggest reason. Even heated chicken waterers can cause devastating coop fires if they are set on combustible material. Those fires often happen at night, when it’s too late to save beloved birds by the time owners realize there is a problem.
  • Providing regular heat doesn’t allow chickens to acclimate to outside conditions. If the power goes out, so does the heat.
  • Chickens can handle a lot of cold. Those Icelandic chickens, the New Hampshires and Delawares? They evolved in areas with frigid winters, before people harnessed electricity.

But there is one good reason to provide a little heat in the winter: Though the birds can withstand way below freezing by fluffing their feathers and huddling together, frostbite can kill tissue on feet and combs if too much humidity is present. A draft-free and well-ventilated coop allows heat to rise and carry moisture from bedding for chickens and to escape near the roof. Usually, deep litter and body temperatures create enough heat. Sometimes though, the coop could use a little help.

Like solar chicken coop lights, a solar heater can make coops more comfortable while remaining off-grid.

My mini-run that uses greenhouse dynamics to warm the coop.

Greenhouse-type Solar Chicken Coop Heaters

When I expanded my flock from five to 35 and built a new coop, I designed a mini-run with a greenhouse chamber. A strong frame jutted from the main coop, about knee-high, facing the sun. Hardware cloth wrapped the top and front. The leeward side housed the pop door, set in solid wood. I affixed a board inside that frame that chickens would have to walk around to enter the coop; this provided a windbreak.

During warm weather, hardware cloth sits bare and cool air wafts in from shaded ground. I wrap it with 6mil plastic when cold rains start to fall, stapling it to wooden boards and leaving the pop door free. Air enters through the pop door but cannot blow straight in; it moves around that board in the middle. Warmed by plastic, air enters the coop, lifts moisture, and exits through small gaps near the roof.

The same concept can be employed by wrapping larger runs in thick plastic, leaving gaps at the bottom so fresh air can enter. It also protects chickens from rain, snow, and harsh wind.

Craig’s Secret Solar Chicken Coop Heater

Craig Bergland, who runs the Facebook page Secret Solar Institute of Northern Nevada, is a genius with the sun’s power. He builds coffee roasters from old satellite dishes, covered in mirrors, pointing at a chamber turned by a solar-powered motor. One of his simplest, and most useful tools is a three-paneled cooker which folds to notebook size and can boil rice within three hours of full sun. Craig knows electricity or fossil fuels may run out during times of crisis or economic hardship. He teaches others how to build the three-paneled cooker and hopes to distribute them among the homeless.

When he suggested a solar chicken coop heater, I was intrigued. My birds do huddle a bit more than I like when winter plummets to single digits.

Here’s a cool fact about Craig: he won’t tell you to finance expensive solar panels. He wants low-cost solutions that remove items from the waste stream. His plans included amber glass bottles, empty metal canisters, and used cooking or motor oil.

We drafted a plan to enclose bottles of liquid inside a reflective, insulated box. Bottles would warm in the sun then we would close the lid, trapping heat and venting it into the coop. It works on the same concept as those barrels of water that gardeners place in off-grid greenhouses to regulate temperatures.

I purchased two sheets of inch-thick R-65 foam insulation with mylar backing. He emptied a few one-liter amber glass bottles “for science.” A friend working at an auto parts store provided old motor oil. While Craig acquired the dimensions and layout of my coop and built the insulated box, he gave me bottles of liquids to test in my freezer.

Inch-thick foam insulation.

Water holds heat longer, but would containers withstand a super-cold winter? Since Epsom salts have greater heat retention and can be drained into gardens, we ran tests to determine if the salts would keep water from freezing and breaking amber bottles. (The answer is no. Glass everywhere.)

We leaned toward oil, which takes very low temperatures to freeze and doesn’t expand the way water does.

“Oil heats up faster,” Craig explained, “but since it only weighs 90 percent of what water does it will not hold as much heat. However, this is a way to take castoff oil out of the waste stream and again, at some point, it could be reused and re-burned.” He also explained that oil will reach higher temperatures than water.

But how hot would bottles get before they burst?

Craig built the box in a long wedge shape, with the largest side opening to face the sun. He filled it with plastic and glass bottles, some with water and others with motor oil. I waited with a point-and-read thermometer until the sun blazed its hottest.

The bottles with oil reached 180 degrees midday in the summer. None burst, but we didn’t excuse the concern that it was possible.

Concerned about breakage and the toxicity of oil, Craig suggested old acetone or linseed oil cans for extreme temperature changes. Auto parts warehouses or paint stores could source free containers. Spray-painting them black would attract more heat. Craig prefers the metal cans because all plastic will eventually degrade in UV light and the heat will soften containers.

Venting heat into the coop is simple. It needs to escape through a side in the heating unit, travel through a very short tunnel, and enter the coop low enough to push humidity up. The tunnel can be made of aluminum cans, their tops and bottoms cut off, duct-taped together. Or it can be purchased from hardware stores.

Regarding pushing heat into the coop, Craig says, “A PV (solar) panel can power 12-volt fans to circulate warm air in daytime, and a small battery will run at night.” Often, the simple dynamic of heat rising up will pull warmth into the coop on its own.

While testing out my coop, I discovered two design flaws. First, unless the land is snowy or wet, dust soon covers the mylar. Not a problem, says Craig. It will still reflect heat. Second, chickens love standing in the heater. This is easily solved by stretching bird netting over the unit or covering the heating chamber with thick clear plastic. Cans would still heat through the plastic, but it would need to be pulled back for any repairs. Tacking foam boards to plywood increases its lifespan through weather, opening and closing, and fowl toenails.


Solar Chicken Coop Heaters for Pennies

“Here in sunny Nevada,” says Craig, “solar is no problem, but solar also works in other areas. There are reports of someone doing summer cooking in Antarctica at one time. And just because the sky is cloudy, that does not mean you will not get some solar heat again. Of course, adding reflectors to your thermal mass will greatly increase the amount of heat available to you throughout the night.”

The key here, says Craig, is to slow the rate of heat loss from containers through the night. Solar reflectors can be made from small mirrors, or even aluminum foil glued to cardboard, but insulation is the key to heat retention. If you build a heater and it cools off too soon before the sun rises, add more insulation and be sure a wooden box is built around the unit.

A few tips on building solar chicken coop heaters out of the cheapest materials:

  • Intersperse a few reused water bottles, filled with water, among the dark containers. This will fill in small, unused spaces and the plastic will not burst if you leave a little gap at the top.
  • If you’re going to use glass bottles, never fill them completely, as liquid expands as it heats. You can top off the bottle after it is hot, but leave at least an inch and a half of space. Only tighten down the lid after the bottle has gotten quite hot.
  • Setting glass bottles inside larger leak-proof containers will contain liquid and shards if bottles do break. These containers can simply be juice bottles with tops cut off.
The heater, all closed up and insulated.

Beyond Solar Chicken Coop Heaters?

It is possible that a simple coop heater could be adapted to provide warm temperatures for other livestock.

Craig’s design can be expanded to incorporate empty black feed or water barrels, set within a box lined with aluminum siding, venting into a barn. It can also cool livestock housing when used in reverse: the top stays open during the night, allowing cans or barrels to lose heat under the stars. The insulated top comes down before the sun can hit containers and cool air vents into barns or coops.

While a solar chicken coop heater may not change the world, says Craig, “It will help reduce some amount of our waste stream, may help keep our chickens a little happier on cold nights, and may give us a little feeling of satisfaction from having reused available resources.”

Have you tried using a solar chicken coop heater? Did you have success? Do you have any tips to share? Join in the comments below.

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