Temperature Coefficient Analysis of Polycrystalline PV Modules Under Field Conditions in Ghana

Abstract

ABSTRACT Photovoltaic (PV) systems in tropical climates routinely operate at temperatures well above standard test conditions (STC), yet field‐measured temperature coefficients remain scarce for sub‐Saharan Africa. This study quantifies the temperature coefficient of maximum power () for a 163.52 kWp polycrystalline silicon array at the Kaleo Solar Farm (KSF) in northern Ghana, using 14 months of high‐resolution field data. Module temperature was estimated using a nominal operating cell temperature (NOCT) model and a performance ratio (PR) based regression was applied to near‐STC records. The field‐measured was −0.473%/°C (95% CI: −0.883 to −0.063%/°C), approximately 31% more negative than the manufacturer's datasheet value of −0.36%/°C. Mean daytime module temperature reached 46°C, with peaks up to 72°C, confirming sustained thermal stress beyond STC. An annual energy yield simulation showed that the field‐measured coefficient implies approximately 7761 kWh/year more energy loss than predicted by the datasheet value—a deficit consistent with the accelerated degradation rates and shortened service lives reported for PV systems across West Africa. These findings demonstrate that manufacturer temperature coefficients systematically underestimate thermal losses in tropical field environments and highlight the need for region‐specific performance standards and design tools that incorporate field‐measured coefficients.