The main objective of this paper is to experimentally assess the real-life outdoor performance of a photovoltaic-thermal (PVT) module against a conventional photovoltaic (PV) system in a hot humid tropical climate in Ghana. An experimental setup comprising a water-based mono-crystalline silicon PVT and an ordinary mono-crystalline silicon PV was installed on a rooftop at the Kwame Nkrumah University of Science and Technology in Kumasi and results evaluated for the entire year of 2019. It was observed that the annual total output energy of PV module was 194.79 kWh/m² whereas that of the PVT for electrical and thermal outputs were 149.92 kWh/m² and 1087.79 kWh/m², respectively. The yearly average daily electrical energy yield for the PV and PVT were 3.21 kWh/kW_p/day and 2.72 kWh/kW_p/day, respectively. The annual performance ratios for the PV and PVT (based on electrical energy output only) were 79.2% and 51.6%, respectively, whilst their capacity factors were, respectively, 13.4% and 11.3%. Whereas the highest monthly mean efficiency recorded for the PV was 12.7%, the highest combined measured monthly mean electrical/thermal efficiency of the PVT was 56.1%. It is also concluded that the PVT is a worthy prospective alternative energy source in off-grid situations.

Fourteen (14) rack-mounted polycrystalline modules installed on the concrete roof of the solar energy applications laboratory at the Kwame Nkrumah University of Science and Technology (KNUST) in Ghana, a hot humid environment, were assessed after 19 years of continuous outdoor exposure. The physical state of the modules was documented using a visual inspection checklist. They were further assessed by current-voltage (I-V) characterization and thermal imaging. The modules were found to be in good physical state, except some bubbles on front side and minor discolouration/corrosion at edge of the cells. Compared with reference values, the performance decline of the modules observed over the exposure period was: nominal power (P_nom), 21% to 35%; short circuit current (I_sc), 5.8% to 11.7%; open circuit voltage (V_oc) 3.6% to 5.6% and 11.9% to 25.7% for fill factor (FF). It is hoped that this study will provide some helpful information to project developers, manufacturers and the research community on the long-term performance of PV modules in Ghana.