Technology
The Solar Dryer dries harvests without electricity and without fuel. It is built on site and grows with its users: from a single unit to an industrial system to a local production site.
Six parts, one cycle of sun and air.
The sun heats the air beneath the cover. No grid power, no fuel.
Cool air flows in from below and keeps the cycle going.
Five stacked trays. The warm air flows evenly through the produce.
Loaded from the side without letting the chamber cool down.
The moist air rises and escapes through the chimney.
Stands without a foundation and can be set up wherever the harvest happens.
The sun heats the air beneath the cover. No grid power, no fuel.
Cool air flows in from below and keeps the cycle going.
Five stacked trays. The warm air flows evenly through the produce.
Loaded from the side without letting the chamber cool down.
The moist air rises and escapes through the chimney.
Stands without a foundation and can be set up wherever the harvest happens.
Module 01
Our Solar Dryer dries grain, vegetables and fruit with nothing but the heat of the sun, without grid power and without fuel. It is built on site with local craftspeople and run by the cooperatives themselves. More of the harvest is preserved, and farmers can sell later at better prices.
Built on site
Welding the frame
The frame on site
Assembling the chamber
Collector in the sun
First harvest on the trays
Module 02
For cooperatives and larger farms: a walk-in solar greenhouse that dries up to 900 kg per batch.
The principle is the same as in the Solar Dryer, only bigger. A shell of 6 mm UV-stabilised polycarbonate lets through 80 to 85 % of the sunlight and keeps the chamber at 45 to 50 °C. Eight fans, powered by their own solar panel, carry off the moist air. A controller monitors temperature and humidity and keeps the drying going even at night.
The produce lies on trays in trolleys. This makes the unit quick to load and unload, and a cooperative can process an entire harvest at once instead of in many small batches. The steel frame is modular and has a food-safe coating.
Benefits
More heat than in the open sun: the harvest dries in days instead of weeks.
No re-wetting in showers and no hurried covering up.
Insects, birds and rodents cannot reach the harvest.
Shorter drying gives fungi and aflatoxin less time.
Colour, aroma and vitamins are better preserved.
Clean, even produce fetches more at market.
Protection from direct UV radiation and shorter drying spare light-sensitive vitamins such as vitamin C.
Module 03, extension
Dried harvest becomes a finished product, right in the village or by the field. The container turns the Solar Dryer into a small production site run by the cooperative itself.
A converted shipping container brings together every step after drying:
Washing, hand disinfection and protective clothing before entering.
Quality control and grading.
Into powder, flour or spice blends.
Weighing, filling and labelling.
Long shelf life, ready for transport, trade and export.
The equipment is adapted to each crop, such as mango, cassava, millet or spices. The container is mobile, delivered fully equipped and needs no permanent building.
Today many cooperatives sell their raw produce straight after harvest, often under time pressure and to middlemen. Processing and packing happen elsewhere, and that is where the profit is made. With the container, processing, jobs and a larger share of the sales price stay in the community, especially for the women who work in processing.
Status
In research with the EES chair at the University of Wuppertal, planned for use in Ghana.
Drying, milling, packing, all in one place.
Profit and jobs stay in the cooperative.
Protected processing to food standards.