An Experiment With Solar Dehydrating

Something I researched early on was solar dehydrators. I have my Excalibur, which I love, but being able to dry foods with just the sun always interested me. What I learned from my early research was that solar dehydrators have limited usefulness in areas of high humidity.

Most of our weather comes up off the Gulf of Mexico, which means most of our weather includes a high level of humidity. That’s not always the case, but humid days outnumber dry ones and changes in our humidity are unpredictable. The other problem is that our sunny summer days often turn cloudy by mid-afternoon. More than once I’ve had to take a solar started dinner and finish it on the stove. Between those two factors, I’ve not been inclined to invest the time and money to either make or buy a solar dehydrator.

My solar oven is a Sun Oven. The other day, I recalled the solar cooking webinar I hosted several years ago for that brand’s manufacturer. (Does anyone remember that? It’s still available online, here.) I remembered that one of the things discussed was how to use the oven as a solar food dehydrator. The technique is different from using it for cooking, so I knew there would be a learning curve. Before the remnants of hurricane Delta blew through, we had a week of day-long sunshine; perfect weather to give this a try.

I chose something inexpensive for my experiment, onions. My first go-round was not successful; I cooked the onions rather than dehydrate them. But we still ate them and I learned from that experience. My second try turned out much better.

Three things turn the Sun Oven into a solar dehydrator. The first is the optional baking/dehydrating rack. Parchment paper keeps the food from falling through the wire.

The second is to set the oven lid on top of the lid latches. To use as a cooker, the latches hold the oven door firmly in place, allowing it to do its moist heat magic. Leaving the lid ajar allows moisture to escape.

The third difference, is to offset the direction the oven is facing, so that it is not pointed directly at the sun. The holes in the door handle enable tracking of the sun to maintain baking temperatures.

By offsetting the direction of the oven to the east, the temperature can be kept at a lower dehydrating temperature. The recommended adjustment is about six inches, and I soon figured out how to adjust it to keep the oven temp in the dehydration range.

With my electric dehydrator, I can just set it and forget it. Using the Sun Oven required frequent checking and adjusting. I learned to rotate the trays and remove onions as they became dry enough.

It took three full days to dry the first batch of onions. Final yield for two pounds of fresh onions was about ¾  of a quart jar dry.

The main disadvantage is that the Sun Oven doesn’t hold much. I had five trays-worth of sliced onions, but only have four trays. But I combined trays as the onions shriveled, and added a new tray of fresh as room allowed. I’m not on a time schedule, so it really doesn’t matter unless humid or cloudy days push in!

So! After this success, I found a DIY solar dehydrator that is claimed to work even in humid weather. It’s at this website. It would still be a huge project to acquire materials and build, but I’m no longer assuming that solar dehydrating isn’t feasible for me. Maybe someday?