What is a Solar Dehydrator?

A solar dehydrator uses the sun's power to dry fruits, vegetables, and herbs without any external energy required. There are various designs for DIY solar dehydrators. This article will focus on the one created by Dennis Scanlin and the Appropriate Technology Program at Appalachian State University. This dehydrator was designed over many years and with the help of various students and teachers. Prototyped initially to be used in the school's Honduras Solar Education Project in the nineties, it continued to be adapted and modified consistently in the following years. The dehydrator takes advantage of the natural process of heat rising to gradually dry foods while preserving vital nutrients.

How Does a Solar Dehydrator Work?

The system works by first having an intake at the bottom of the solar dehydrator. From here, the air draws into the collector box, where the sunlight passes through the clear glass or plastic cover and absorbs into a dark mesh screen. This screen transfers the absorbed heat to the surrounding air, which then naturally rises to the drying chamber on top. At this point, as the air moves up and out of the collector box through vents. Negative pressure is created at the base of the system, drawing more air and repeating the process. As the warm air reaches the drying chamber, it passes over the fruits, vegetables, and herbs, drawing moisture out of them as it moves through to the vent at the top of the section.

Can You Buy a Solar Dehydrator?

Unfortunately, you will not find Dennis Scanlin's solar dehydrator retailing at stores. But he has provided detailed documentation on creating a solar dehydrator at home for Mother Earth News . The prices of the DIY solar dehydrator range depending on the cost of materials needed. With necessary tools already at your disposal, material costs can range from $300 to $500. But at the end of the design, you have a dehydrator that can run every sunny day, saving you money over time with the cost of food preserved and waste prevented.

What Are the Benefits of Solar Dehydrators?

A solar dehydrator is a great way to dry out your food and herb crops. While traditional drying methods put your crops at risk of sun exposure, solar dehydrators indirectly utilize sunshine for preserving your harvest. The primary benefits of properly drying foods, reported by Scanlin, come from how the process affects the nutritional value of food, the survivability of microorganisms, and plant enzyme response.

What Are the Limitations of Solar Dehydrators?

As great as the solar dehydrator is, it does have limitations, the primary being sunlight requirements . For a solar dehydrator to function optimally, it requires full sun or a partially sunny day. The collectors can absorb more potential energy with direct sunlight, transferring it into the air for better drying. If you live in a location with a lot of shade may have trouble collecting enough light to gather optimal heat. Scalin's reflectors can help with that, but some systems may require additional manual operation for optimal production. Solar dehydrators also have limited drying space for the amount of time it requires to dry fruits or vegetables. It can dry 11 trays, holding a total of 10 pounds of fruit or vegetables over two sunny days. These numbers vary depending on what you are drying and how warm the days are. Produce with more moisture will take longer to dry. Also, produce at the bottom of the drying chamber will often dry out faster because they receive the hottest air first. A test done by Scalin showed that the upper layers of the dehydrator drying box fluctuate and can be 50F cooler. In comparison to plug-in food dehydrators, the solar option is large and bulky. Requiring approximately least seven feet in length and six feet in height, it will take up a good portion of your patio or balcony . If space is limited, this may not be the best option for your site.