The normal incidence angle, as applied in the common qualification testing at Standard Test Condition (STC) is hard to achieve for a fixed photovoltaic system due to the movement of the sun. This causes variations in the module reflection which in turn causes a lower than predicted performance of the module. The understanding of this loss factor is therefore important for an accurate energy prediction of PV modules. This study investigates experimentally the effect of incidence angle under real operating conditions for different PV technologies. A measurement system was developed and commissioned using a custom-built two-axis tracker. The tracking system was used for systematically varying the angle of incidence while the short current of the module was monitored. The current-voltage characteristics were measured with specifically developed hardware and overall system control was achieved by a programme written in LabVIEW. This study investigated the variation of nominal short circuit current with the different angles such as: azimuth angle, tilt angle and angle of incidence. Alongside this the variation of the maximum power of the module under different STC state was calculated For Loughborough latitude 520 modules of tilt angle of around 300 facing south is the best to achieved maximum short circuit current and for the façade system the azimuth angle more 600 gives maximum current.