In a PV plant the solar modules account for about half the value of the whole system. Therefore, if the modules have a serial defect, a large part of the investment may be at the risk of being lost. Internal module damage is not normally visible to the naked eye. A thermographic examination reliably reveals to the experienced technician different types of defect in a module and their effects on the performance of the system. We perform thermographic checks with a very high-resolution system and by trained and experienced personnel. Typical service: 100 % module check.