HI-85-04-2 -- Results of Active Solar Control System Testing and the Performance Effects of Sensor Degradation PDF

The Solar Energy Research Institute has been involved in testing control systems, including thermistors, switches, RTDs, integrated circuit sensors, and controllers, since 1981. The results show serious reliability problems with control systems. Sensors degraded or failed from exposure to high' temperature, and controllers did not meet specifications. The effect of sensor degradation on annual performance has been quantified for a particular system configuration in four different locations; as much as 50% of the collected energy can be lost, and the auxiliary energy requirements can increase by 250%. Test results of three prototype control systems for solar space heating' are also briefly discussed.