Effect of tilt angle on the performance and electrical parameters of a PV module: Comparative indoor and outdoor experimental investigation

Photovoltaic (PV) system's performance is significantly affected by its orientation and tilt angle. Experimental investigation (indoor and outdoor) has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions. There were two experimental modus: 1) varying module tilt under constant irradiation level, 2) varying irradiation intensity at the optimum tilt set up. For the former scheme, the irradiation level was maintained at 750 W/m2, and for the later arrangement, the module tilt angle was varied from 0o to 80o by means of a single-axis tracker. Results show that under constant irradiation of 750 W/m2, every 5o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor. In contrast, for the same condition, efficiency decreases by 0.54% for indoor case and by 0.76% at outdoor. On the other hand, for every 100 W/m2 increase in irradiation, solar cell temperature rises by 7.52°C at indoor and by 5.67°C at outdoor. As of module electrical parameters, open-circuit voltage, short-circuit current, maximum power point voltage and maximum power point current drops substantially with increasing tilt angle, whereas fill factor drops rather gradually. Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15o and orienting a PV module this angle will maximize the sun's energy captured and thereby enhance its performance.