Preserving garden bounty is an important part of self-reliance. One efficient way to preserve the harvest is by dehydrating food. Electric dehydrators are a great way to go. However, in a true survival scenario, the luxury of electricity may not be available. Our infrared solar dryer is an effective way to dry fruits and vegetables using only the power of the sun.
Why use infrared solar drying to preserve fruits and vegetables? An infrared solar dryer takes advantage of the sun’s free energy. The food is not exposed to sunlight which leads to vitamin loss. It is simple to construct and best of all it does not require electricity to preserve fruits and vegetables.
We have been searching for the right solar dehydrator design, and were excited when we came across Tom Bartels’ infrared solar dryer. The design is simple, yet highly effective.
You can learn more about Tom Bartels and his biointensive gardening techniques here. He has some great ideas that we are implementing into our homestead.
How Does an Infrared Solar Dryer Work?
With an infrared solar dryer, the energy from the sun radiates through the “greenhouse” cover and is absorbed by the black metal plate. This energy drives through and into the food chamber, drying the food. The humid, heated air is exhausted into the heat channel beneath and flows up and out of the dryer. This rising air pulls air in to fill the vacuum and the process continues.
Why Use an Infrared Solar Dryer
An infrared solar dryer is an amazing tool that uses the free energy of the sun to dehydrate food. Because it does not use electricity, it is an ideal way to preserve food every day as well as during a grid-down event.
The design protects the food from sunlight, protecting the fragile vitamins. It also keeps the food away from flies and insects. Dehydrated produce can be shelf stable for several years without the need for refrigeration. It truly is an effective way to preserve the harvest.
This infrared solar dryer design is simple to construct and has no moving parts other than a set of hinges to open the lid. It is incredibly sturdy, should require little maintenance, and provide many years of service.
How to Use an Infrared Solar Dryer
Using an infrared solar dryer is incredibly simple. Simply lift the lid and place the prepared food on the screen inside of the dryer. Close the lid and let the sun work its magic. Depending on the food and the sun, food will be dehydrated in a day or two to a week.
Step-by-Step Instructions to Build an Infrared Solar Dryer
Design credit for this dryer goes to Tom Bartels. You can learn more about his work here. Tom’s design is 2 feet by 8 feet. We wanted something a bit smaller so our solar dryer is 2 feet by 4 feet. We plan to construct a total of 5 solar dryers to meet the needs of our family.
This is a list of the basic materials that we used. Most of the materials that you may need can be purchased at your local hardware store or from Home Depot online.
- Lumber – 2 x 2, 4 x 4, and plywood.
- Tin sheet
- High-temperature black spray paint
- Stainless steel screen
- Pro-panel metal
- Polycarbonate sheeting or greenhouse plastic
- Non-toxic stain
- Roofing nails
- Grabber screws
- Eye lag screws
- Lag bolts
- Carriage bolts
- Roofing screws
- Support chain
- Staple gun
- Thermometer (optional)
Paint One Side of Tin Sheet
Cut the lumber to the size of dryer you want to build. Tom Bartels solar dryer was 2 feet wide by 8 feet long and was divided into 4 compartments. Our dryer is half the size measuring 2 feet by 4 feet.
We wanted smaller compartments so we have 3 separate drying compartments in our frame.
Lay Out on Working Surface
To simplify the construction process, you will want to start with an elevated working surface. Lay out the lumber to form the box.
Attach Painted Tin to Frame
We predrilled holes in the both the tin and the wood. The tin was attached to the wood using roofing nails for a smooth surface.
Remember that the painted side of the tin is exposed to the sun and the unpainted side goes next to the food. We want to make sure that there are no toxins near the food.
Build Tray Base and Attach Screen
Build the frame and then attach the stainless steel screen to the top. We used a combination of staples and screws to secure it.
Attach Pro-Panel Under Screen
We repurposed some used pro-panel or metal roof panels that we installed underneath the stainless steel screen. This doesn’t come in contact with the food so we were comfortable using recycled material.
Attach Top to Bottom with Sturdy Hinges
It is important to use heavy duty hinges. The top of the dryer is heavy and sturdy hinges will help it to last a very long time.
Attach the polycarbonate to the top of the dryer.
We repurposed this handle. Simply attach it to the top box to make it easy to open the lid.
Attach Legs to Maintain 13 Degree Angle
The angle of the solar dryer box should be at 13 degrees. This angle encourages the warm air to rise, taking the moist air away from the drying produce. Any steeper than 13 degrees and the food slides down to the bottom of the trays.
Tom’s original design included legs made of 4×4 posts with a cross bar to brace it. He also used a support wire to keep the top from flopping backwards and a prop rod to make it easier when filling the dryer.
We experience heavy winds in our area so Jonathan (being an engineer) redesigned the legs to make sure that it wouldn’t topple over in a storm.
Instead of a support wire, Jonathan repurposed an old dog chain to support the lid while filling and prevent it from flopping backward. It works really well. A 2-foot by 8-foot solar dryer would require supports at both ends using the chain due to the increased weight.
Install Wind Barrier
When we first started dehydrating in our solar dryer we were disappointed because we just couldn’t get it to achieve acceptable temperatures. Jonathan realized that the cold winds were blowing into the dryer and added a piece of metal flashing to take care of that.
That wind barrier allows this dryer to regularly achieve temperatures of 140 to 170 degrees Fahrenheit.
What Types of Food Can Be Dried in an Infrared Solar Dryer?
The internal temperature of the infrared solar dryer rises with the intensity of the sun. It will cool off when the sun goes down. The fluctuation in temperature is fine when drying fruits and vegetables, but not for any food, such as meat, that requires a constant temperature. Follow the recommended guidelines for preparing produce for dehydration.
Can I dehydrate fruit in an infrared solar dryer?
Absolutely. Start by washing high-quality ripe fruit. Thinly slice fruits like bananas, apples, pears, strawberries, kiwis, mangos, and pineapple. I only peel the fruit if the peel isn’t edible such as bananas and pineapple. Apples and pears get to be dried with the skins on.
I cut apricots and small plums in half and then invert them. That pops the center out and helps to flatten them.
Small fruits such as grapes, blueberries, and cranberries can be left hole. You will get better results if you pierce the skin before drying. I cut larger grapes in half before drying them.
Don’t be afraid to try dehydrating watermelon. Melons are amazingly sweet when dried. They take significantly longer due to the high water content.
Can I dehydrate vegetables in an infrared solar dryer?
Yes! My favorite vegetables to dehydrate include diced celery, sliced squash, spinach, kale, Swiss chard, cabbage, diced carrots, diced beets, broccoli, cauliflower, peas, peppers, and cherry tomatoes. Just about any vegetable dries well.
Greens are packed with nutrition. Once they are completely dry, they will store for a couple of years if packaged correctly. I vacuum seal the greens in canning jars. Dried greens are a great way to add nutrition to your diet.
- Grind the greens into flour (in a coffee grinder, or similar) and sneak a few tablespoons into muffins, brownies, pancakes, or cookies for a nutritional boost.
- Add a few tablespoons of dried greens to soups, stews, or beans.
- Make dried greens a standard ingredient in your morning fruit smoothie.
Can I dry meat in an infrared solar dryer?
It is not safe to dry meat in an infrared solar dryer due to the fluctuation in temperature. Meat should be dried in a dehydrator that can maintain a constant safe temperature.
Can I dry herbs in an infrared solar dryer?
The infrared solar dryer is comparable to the oven method for herb drying. Herbs are usually dry within just a couple of days during the heat of the summer.
Food Preservation Using the Power of the Sun
The sun is an amazing resource. This infrared solar dryer takes advantage of that free resource, and lets you harness the energy to dehydrate produce.
We are preparing for a long term grid down event. This basic technology lets us safely preserve the harvest without using any of our precious fuel supplies. It is inexpensive and should last for many years. This solar dehydrator is definitely an asset in our journey to become more self-reliant.
One of the things that I like best about the infrared solar dryer is that it is foolproof. It requires no tending on my part to successfully dry the food. If I leave it in a day or two after it is dry, no harm done. All I have to do is put the prepared food on the screen, close the lid, and walk away.
A huge thanks to Tom Bartels for sharing his amazing design with us. You can learn more from Tom Bartels here. You can learn more about his biointensive gardening techniques in our post, Biointensive Victory Gardens: Higher Yields with Less Work.
Thanks for being part of the solution!Jonathan and Kylene Jones