Original Article

Using the equivalent cell temperature for power matrix calculations

European Commission, Joint Research Centre, Ispra (VA), Italy

^* e-mail: Hanna.ELLIS@ec.europa.eu

Received: 28 June 2024
Accepted: 8 October 2024
Published online: 19 November 2024

Abstract

Performing measurements and compiling a power matrix (IEC 61853-1) is a useful tool for illustrating the energy production of a PV module at different levels of irradiance and temperature. At the European Solar Test Installation (ESTI) a steady-state solar simulator can be used to determine these matrices. The steady-state solar simulator irradiates the PV module from the front side, which heats the module to the desired temperature. However, this causes a temperature difference between the front surface of the module and the rear, where the temperature sensor is attached. This temperature difference, between the measured module temperature (T_m) and the temperature of the cell junction, gives rise to errors. In this paper, a correction procedure according to the determination of the equivalent cell temperature (ECT) of photovoltaic devices by the open-circuit voltage method in IEC 60904-5 is proposed and evaluated. In this study the difference between the T_m and the ECT was determined to about 1 °C to 3 °C, resulting in a deviation of the P_max value in the power matrix up to about 1.5%, for a monocrystalline PV module.