A humidistat to control a solar powered DC fan for grain drying and ventilation in remote areas

In developing countries small-scale dryers and storage facilities are mostly monitored and controlled manually, which is complicated and prone to errors. Simple, affordable control devices can help farmers in the management of their systems. In this study, a low-cost, low-energy microcontroller-based humidistat was constructed to control the operation of a photovoltaic driven DC fan. The fan was connected to a modification of a typical Ethiopian drying and storage structure for ear maize. Fan current and voltage, insolation, and ambient temperature and relative humidity were recorded at five minutes intervals to test whether the humidistat performed as expected. The humidistat is reliable, costed less than 10 €, and can be easily modified in software and/or hardware to control fans or other components based on other criteria.