An innovative method for determining the junction temperature of a photovoltaic cell

Abstract

An innovative method for determining the junction temperature TJ as a function of the cell voltage V of a photovoltaic (PV) cell for varying operating power levels at pre-determined values of irradiation levels is presented. Since the junction of a PV cell that is in operation is inaccessible for obtaining a measure of TJ, a novel indirect temperature measurement method suitable for determining the TJ is proposed in this paper. The electronically controllable load required to establish different operating power levels for obtaining the TJ - V characteristic of a photovoltaic (PV) cell is implemented with a MOSFET, suitably controlled to act as a variable load resistor. Microcontroller based hardware with associated software were developed to automate the entire measurement process. Results obtained from a prototype TJ - V measurement unit built and tested establish the efficacy of the proposed method.