The Hohenheim-type dryer results in faster drying and higher quality than traditional open-air
methods. In Turkey, for example, apricots can be dried in 2 days – half the time required by
traditional methods. An important feature contributing to consistent quality is the use of
photovoltaic powered fans for fo
rced convection. The controlled drying process results in
high-quality. The acceptable load for the dryer ranges from 1.5 kg/m²
for medicinal herbs to
25 kg/m² for rice or coffee. For a standard dryer with a 20 m² drying area, this corresponds to
30 to 500 kg per batch
Some dryers made in Thailand are equipped with a gas powered air-heating unit to allow
drying during the six-month rainy season. In contrast, Turkish weather is dry enough to allow
the all-solar dryers to operate well with twice the standard drying area. Local manufacture of
the Turkish models allowed a total installation cost of less than 1000 US$ in 1997, resulting
in a payback period of only one year. The models used in Thailand were more expensive due
to the gas-powered back-up heating unit.