Described herein are the results of the FY1994 research program for international joint technology development for solar energy utilization systems. The joint study with an Indonesian research institute takes a model of lumber drying plant for the design and feasibility study. All the parts it needs are technically available in Indonesia, except carbon fiber sheets and electronic devices for controlling purposes. The drying cost is higher than that of a plant which procures charge-free wood fuel, but lower than that of a plant which procures fuel at 30$/t. A cacao drying plant model is also studied. The feasibility study shows that the initial investment for the blowing-up model is much higher by 60% to 100% than that for the conventional plant. Its fuel cost is lower by 11% than that of residual oil but 27% higher than that of wood. 4 figs.