Tips for FAST Solar Food Drying!

Fast drying is key to optimal food quality and to maximizing your productivity as a food preserver. Most of the work in food drying goes into the food prep: washing and slicing. The rest is easy. You can dry a full load of food in just one or two days of sunshine with a good solar dryer.

Fast drying requires three things: heat, air movement, and proper food prep. Here are my tips to fast solar drying:

Maximize solar heat input to your dryer.

A solar food dryer is made to operate outdoors in any sunny location such as a yard, deck, or patio. Check for trees and buildings that may block sunlight at various times of day and pick the least obstructed location for your dryer.

Clean the solar glazing with a wet cloth before each drying session to remove any dust that may accumulate on the top. Dust on the glazing can easily reduce your solar energy input by 10% to 20%.

Get maximum solar rays by adjusting your dryer to face the sun. I usually adjust it three times: for morning sun, midday sun, and afternoon sun.

Optimize air flow.

Airflow is necessary to remove moisture and replace moist air with dry warm air. Solar dryers rely on natural convection instead of mechanical fans to move the air. Warm air rises, so controlling the top vent on the dryer regulates air flow.

Adjust the venting on your dryer to allow maximum airflow, while also maintaining adequate drying temperatures. Drying temperature is up to you, but I like to dry at 120 to 140 degrees F, because food dries faster at higher temperatures.

Proper food prep.

Proper food prep will greatly speed drying. Slice all food to a uniform thickness so that each piece will dry at about the same rate. Generally, I try to keep all foods to a thickness of 1/4 inch maximum.

Cut through fruit and vegetable skins so that the flesh is exposed. Skins can greatly impede drying.

Load food so that there is a little space around each piece of food to facilitate air movement. Overloading the dryer will slow drying and will not save time.

Start your solar drying in the morning on a day with a good sunny forecast. Ideally you want to transfer your prepared food to the dryer quickly to preserve nutrients. You also want your dryer to be getting morning sun so it will start drying immediately.

If you have a large, wet load of tomatoes or fruit that will take more than one day, you need a sunny day on the first day of drying to remove most of the moisture and start the preservation process. This will enable to food to overnight without losing quality.

This is all you need to get consistently great results.

If you have a load that requires a second day of drying, and the weather gets partly cloudy on the second day, you will still get good results, even if you need to take an extra day, since your food already has most of the moisture removed and the preservation process has started. However, if your weather turns overcast or rainy on the second day, make use of the backup electric heating (if available) to finish off the sun's work.

Happy solar drying!
Eben Fodor

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