Why do solar systems fail

Reliability evaluation studies carried out at Argonne National Labs are described. At present, conventional domestic hot water systems are more reliable than solar domestic hot water systems. According to reliability studies, several problems are most likely to affect the performance of a solar system. These are: freeze problems, control system decisions, system interconnections, component failures, and materials performance. Solar collector failures are cited as the major cause of low reliability. The need for more research in materials and solar systems is stressed. (MJJ)