Cell Temperature Determination based on IEC61215: Solar Photovoltaic Experimental Study of Tropical Malaysia

Abstract

Most commercial photovoltaic (PV) module data sheets include Nominal Operating Cell Temperature (NOCT) values, which assist PV system designers in estimating module temperatures under real outdoor conditions. However, the typical NOCT values of 45°C to 47°C do not account for tropical climates. This study seeks to develop an adjusted NOCT mathematical model and determine revised NOCT values suited for tropical conditions. The new proposed NOCT model follows the international standard IEC61215 but incorporates updated tropical Standard Reference Environment (SRE) parameters: solar irradiance (SI) of 800 W/m², ambient temperature (AT) of 31°C, and wind speed (WS) of 1 m/s. This modified NOCT model demonstrates improved accuracy over the existing model, with an average reduction of 2% in percentage error, root mean square error, and mean average percentage error. Outdoor NOCT testing conducted in Shah Alam, Malaysia, uncovered much higher NOCT values for various PV modules technology: 55°C for monocrystalline, 57°C for polycrystalline, and 59°C for thin film. These results emphasize the inadequacy of current NOCT values in commercial PV module data sheets, which do not accurately reflect conditions in tropical climates. The revised NOCT values from this study offer crucial thermal reference data for PV system designers, integrators, and researchers working in tropical regions, particularly Malaysia.