Design,Construction and Evaluation of a Parabolic Concentrator-Photovoltic (PV) System with improved efficiency

One of the major problems in concentrating solar radiation on the Photovoltaic (PV)
module is the uneven illumination of the solar cells. The non – uniform irradiance
creates hot spots on the module and increases its temperature. The high temperature
results in a lower efficiency and increases the degradation rate of the PV module. To
solve both problems, a Parabolic Trough Solar Concentrator (PTSC) was designed and
constructed from locally available materials. The configured Parabolic Concentrator
Photovoltaic (PV) system’s efficiency was evaluated using diffuse reflector materials
(aluminium foil, rolled aluminium and galvanised aluminium) as reflecting surfaces.
Use of diffuse reflector materials resulted in an increased and even irradiance on the PV
module compared to a module without concentration. Aluminium foil recorded the
highest irradiation of 2148.62W/m2 and module temperature of 52.9oC. Rolled
aluminium recorded irradiance of 2133.20W/m2 and a temperature of 47.8oC. This
would be attributed to their high total integrated reflectance 95.4%, aluminium foil and
86.7% for rolled aluminium. Galvanised aluminium recorded irradiance of 1655.0W/m2
and the lowest temperature of 29.6oC. Its total integrated reflectance was 77.3%.
Galvanised aluminium showed the highest efficiency of 15.1%, aluminium foil gave
13.5% and rolled aluminum 12.7% compared to the solar module without the
concentrator which showed an efficiency of 11.3%. Hence, galvanised aluminium was
the best diffuse reflector material as it scattered solar radiation on the module which
resulted in the lower module temperature and increased efficiency of the Parabolic
Concentrator Photovoltaic (PV) system.