They previous group has built a solar dryer with a steel frame, plastic sheets on the sides and the drying box on top (see picture). The main problem was that the plastic was not durable; it was affected by the sun and there formed some cracks.
Because of this, we will try to make a design without plastic sheets, or we will use a better quality plastic.
The other improvement opportunity lies with the steel frame. Because of the costs of steel, its better to use a cheaper material. The challenge is to find a cheaper but still durable material to make the frame.
Besides the construction related subject, we can also learn a lot from all the other. Their report is a valuable source of information.