Solar Crop Dryers

Beautiful solar dryer image courtesy of David Lockie, LowCarbonEconomy.com

Fresh fruit, vegetables, and herbs can be dried throughout the year to preserve the fresh produce for seasons when they cannot be grown, to make use of excess yields so crops don’t spoil before they are used, or just because they are enjoyed as yummy snacks.

From a storage perspective, drying is one of the best ways to preserve food, even better than canning.[1]   Drying fruit and herbs in the sun is easy; food is simply laid out to dry in the sun, hung over branches, tied up to hang, or laid in baskets.  However, for those interested in selling dried crops, this can be very time consuming, and may take away from the color and freshness of certain crops.  Exposing fresh produce to rain, insects, dust, and direct sunlight all degrade the quality of the produce. 

Solar dryers improve the final quality of the food, are typically less expensive then mechanized food dryers, require no energy to operate, reduce drying time, and require less space to dry.  If a fan is used instead of relying on natural convection, only half as large a solar collector is required and drying time can be reduced by a factor of three.[2]  Faster drying times can prevent molding, allow crops to be preserved swiftly, and dry food more completely.  The key is to dry the produce or herbs as swiftly as possible without actually cooking the food.  If the temperature is too low at the start, microorganisms may grow before the food is preserved.  On the other hand, if the temperature is too high, the surface of the food hardens making it difficult to dry the interior.  Food that is dried up to 10 to 20% moisture content reduces the chance of food spoiling from bacteria, yeast, mold, or enzymes.  This type of system is particularly useful in humid tropics or other places where the harvest is during a rainy season.

Belize has very few industries, especially for those individuals residing in rural regions of the country.  The availability of locally produced, inexpensive solar dryers may allow for more individuals to take advantage of this area.  Because the crops can be dried more swiftly, participants can sell crops more rapidly therefore increasing their income.  The solar dried crops retain more color and freshness, therefore increasing the quality of the product, which potentially increases the value of the crop at market.  Increased income is also generated with the packaging/marketing strategy learned in the workshops.