I happened onto this manual just now and it got me to thinking about solar drying again.
click the image to download the manual
The document was prepared as a training manual for a Zimbabwian project funded by the Austrian Embassy titled Establishment of a production, sales and consulting infrastructure for solar thermal plants in Zimbabwe.
Its a comprehensive manual covering many designs and processes which you will see in illustrations from other documents you have read over the years. The 110 page book contains descriptions of many different dryers as well as examples of many different crops and their dryers. It also presents a great deal of technical data on drying but even though the title of the project nothing about markets, packaging and selling.
Solar drying should be all the rage currently giving its potential to impact global food shortage and climate change – but we still seem to be where we were decades ago.