Factors influencing the conversion efficiency of a PV module Vaal University of Technology Augustine Ozemoya Vaal University of Technology Augustine Ozemoya Energy Postgraduate Conference 2013

Outline Introduction A prognosis of the scientific advisory board on energy usage 2100 Practical Setup Experimental results Future work Conclusion

Introduction The ratio of solar energy to output electrical energy is considered as the conversion efficiency. More than 80% of the solar radiation reaching the PV module is not converted into electrical energy; it is reflected or transformed into heat energy. Heat generated in PV modules leads to the problem of a decrease in the conversion efficiency of energy and is referred to as temperature degradation. A general rule is the higher the surface temperature of the PV module, the lower its efficiency and hence its output power.

Global energy usage to 2100 It is predicted that solar power will become the dominant energy source in the future. A branch of solar energy research that has received worldwide attention is the PV renaissance. South Africa's economy is heavily dependent on coal and EIA estimates show that nearly 70% of the country's total primary energy supply is derived from coal.

Practical setup  Block diagram A PV module connected to a 24 V DC-DC converter and a constant load resistance of 6 Ω. A DC-DC converter is used in place of solar charger to regulate the output power from the PV module. The data acquisition equipment consists of a data logging interface circuit (DLIC) and a DAQPro 5300 data logger. Temperature sensors PV Panel set at an orientation angle of 0 o and different tilt angles of (16 o, 26 o & 36 o ) Data acquisition system DC-DC converter Constant load

Practical setup The position of temperature sensor on the PV panel

Experimental results

The back surface temperature is a good approximation of the actual cell temperature and studies have shown that solar cells typically run 3°C warmer than back surface temperatures for glass–glass laminate constructions.

Experimental results The tilt angle has a major impact on the solar radiation incident on a surface. Day Night

Future work Implementing a cost effective method to control temperature degradation and improve output power. Using different cooling techniques for PV modules to try and control the surface temperature in order to provide optimum output power Conclusion The results show that ambient temperature as well as the tilt angle impact significantly on the surface temperature of the PV module. The conversion efficiency of PV module depends to a large degree on a constant surface temperature of around 25°C Going beyond this point leads to a considerable amount of heat being generated within the PV module leading to the problem of a decreased conversion efficiency and subsequent temperature degradation.