Using the chimney solar dryer to dehydrate fruits and vegetables

This 5-page document includes directions for how to use the chimney solar dryer to dry fruits and vegetables, with troubleshooting tips and resources for more information. It is Section 2 of the Chimney Solar Dryer Manual.

First, test your solar dryer

We recommend giving the dryer a test run to make sure all the pieces fit well together, that there are no air leaks or gaps in the plastic, and to measure the temperature (if possible) at different locations within the dryer table. If the dryer is working well, strips of tissue paper hanging from the center pole under the clear plastic will flutter, the plastic over the table will be concave (due to suction from the chimney), and you will see shimmering at the top of the chimney’s shadow.

Prepare fruits and vegetables for drying

Produce should be clean and undamaged. Bulky products dry faster if they are cut into pieces prior to drying. It is best to begin the drying process in the morning to give the maximum drying time before sunset.

Fruit and vegetable product size

Thin items like herbs and leafy greens may dry in a few hours, while large products like whole apricots or whole bananas will require several days to dry. You can decrease drying time by removing pits, peeling the product, and/or cutting it into thin (6 mm) slices.

Load produce on trays 

Load the trays with whole or sliced products (fruits and vegetables). The pieces can overlap slightly because they will shrink as they lose moisture. Make sure the tray is not too heavy to lift.

Preheat area in the chimney solar dryer

The first tray space (farthest away from the chimney) should be left empty (see photo). Leaving the first tray space empty allows the air to heat before it contacts the product.

Rotate trays during drying process

Rotate the trays according to the thickness and water content of the product. Generally, thicker and moister products require more time and thus more rotations compared to leaves and other similar products. It is advised that you rotate the trays 2 to 3 times during the drying process. Move the trays closest to the chimney to the opening of the dryer and the trays from the opening next to the chimney. Switch the bottom tray with top tray if trays are stacked. By rotating trays and leaving an open preheat area, you will get a more uniform moisture content across all of the product in the dryer.

Check airflow and plastic cover

The clear plastic that covers the trays should not touch the fresh product; this may cause burning or incomplete drying. The plastic should be as taut as possible, creating a tent over the product and trays. Make sure that there is plenty of airflow through the dryer, especially above and below the product. Remember, ambient air enters, quickly warms up and dries the product. Warm, humid air exits through the chimney.

See the "Drying fruits and vegetables with a chimney solar dryer" PDF for diagrams and more details.