ABSTRACT
A simple method was developed with which PV-system owners that are non-PV-specialists can check each month whether their system has been functioning well. It requires monthly kWh-readings, an estimate of the Performance Ratio, monthly insolation values of a nearby meteorological station and a tilt conversion factor. A field test with 36 PV-owners showed that the method worked well, in the sense that the owners could work with it and in the sense that failures were detected that very likely would have gone unnoticed otherwise. For large scale application of the method solar radiance and tilt conversion factors should be easily accessible, for example through newspapers or an internet site.
