Backup Source of Energy Necessary for Solar Drying to Ensure High Quality Product

This insight and supporting research was developed by Kopernik Fellow and UC Berkeley Master of Public Policy student, Tarunima Prabhakar, together with Kopernik's Strategic Initiatives Team.

While researching the unmet needs of smallholder farmers in Indonesia, we found that ineffective crop drying and dehydrating techniques were causing considerable economic losses. Because electric dehydrators are not a viable option for many rural areas with limited or no electricity, often the most common method of drying crops is placing them directly under the sun. This practice is often unhygienic, can be time-consuming, and is heavily reliant on weather conditions.

So, we wanted to develop a simple, solar-based technology that was faster and more hygienic than the direct-sun drying method, cheaper than electric dehydrators, and consistently produced dried fruit of equal or higher quality than the currently used method.

While our prototype performed at least 15°C above the outside temperature during sunny weather, it struggled to maintain this temperature during cloudy conditions or once the sun goes down. The chamber conditions closely mirrored the weather outside and therefore could not maintain a consistently high enough temperature to produce a uniform quality of product.^{Results of two indicative days of temperature monitoring}

When conditions were right and the sun was out, our dried fruit outperformed both direct sun-dried fruit and store-bought electric dehydrated fruit on blind sensory tests.²  But when it was overcast, the result was neither better quality nor more efficient than sun-drying.

Just as Elon Musk said, when talking about how crucial battery power is for a sustainable energy future, “the sun doesn’t shine all the time”. Similarly, in order to achieve a consistently high quality product, batteries or a backup source of energy might be needed to complement the sun for effective drying or dehydrating.

Have you had any experience using solar power for drying or dehydrating?

^{Kopernik Solar Dehydrator based on Appalachian Dehydrator by D. Scanlin}