Figure 7: A Hohenheim dryer, Ghana. Black paint being applied to the collector. Photo:
There are several other types of solar dryer, many involving insulation and different air-flow
methods. Some have a chimney fitted to the outlet to encourage better airflow, other make use
of external heating sources such as hot water to allow further drying at night or when cloud cover
prevents efficient drying. However, all are essentially variations on the three described above.
Sun drying compared with solar drying
Figure 8: View inside a Hohenheim solar tunnel dryer. Photo: Tony Swetman.