Performance Evaluation and Software Simulation of the 5 6 kWp Murdoch University Library Photovoltaic System

T his paper assesses the performance of Murdoch University’s 56 kWp, roof mounted photovoltaic system between August 1 2010 and July 31 2011 and makes comparison with similar systems from the Desert Knowledge Australia Solar Centre (DKASC) in Alice Springs. Modelling of the system was also undertaken using the program PVsyst and further comparison made. It was found that the average performance ratio (PR) for the system over the analysis period was 0.74, with the poly-crystalline (poly-Si) component of the system having slightly higher PR than the mono-crystalline (mono-Si) component at 0.75 and 0.74 respectively. These results also compared favourably with free standing and roof mounted DKASC arrays. It has been found that performance is most significantly affected by module operating temperature. A linear regression analysis of module and ambient temperatures with solar radiation showed that module temperature can be approximated from irradiance and ambient temperature by the formula Tmod = 0.303S + Tamb (S=Solar irradiance in m W/cm 2 ), which is in reasonable agreement with literature (Wenham e t al. 2006). Due to the system’s sheltered position, wind was found to have negligible influence on module temperature. As well as the performance assessment, the second objective of the paper was the detailed modelling of the system carried out in the simulation package, PVsyst. It was found that PVsyst provided an acceptable estimation of expected system output and PR, with an average of 0.73, taking into account temperature and shading influences.