Component Reliability and Control System Testing

The Solar Energy Research Institute has been involved in testing active component reliability and control systems. Six test loops were constructed to thermally cycle drain valves, check valves, air vents, vacuum breakers, tempering valves, and polybutylene piping. Results showing poor reliability of some of the components and limited performance of others lead to a better understanding of certainfailures in the field and present designers with realistic expectations for these components. The seven SDHW control systems tested included thermistors, switches, RTDs, IC sensors, and controllers. Serious reliability problems included sensor degradation or failure from high temperatures, and controllers that did not meet specifications. As much as 50% of collected energy can be lost because ofsensor degradation, and auxiliary energy requirements can increase by 250%.