A comprehensive analysis of recombination and resistive losses in silicon solar cells induced by co-firing process

Abstract

In this paper, we critically assess and present characterization methods to observe the impact of co-firing conditions initially on global parameters and subsequently, on local parameters of solar cells. Two different schemes, namely Scheme-A and Scheme-B, where the former is a closed and static system and the latter is an open and dynamic system are used to achieve two different co-firing conditions. Solar cells co-fired with these schemes are used in this study for investigating both global as well as the local performance parameters, majorly responsible for the losses in solar cells. In order to investigate the lateral variations of the diode parameters contributing to the loss mechanisms, combination of spatially resolved measurements have been carried out including light beam-induced current, photoluminescence and dark lock-in thermography. The proposed set of characterizations and methodology qualitatively compare the local two diode model parameters of each pixel in the spatially resolved images of a solar cell, responsible for the losses in all three performance parameters; open circuit voltage, short circuit current density and fill factor. The analysis reveals that even optimum firing conditions in two different schemes affect the surfaces in different ways where recombination and resistive losses become major contributors towards the power losses, primarily reverse saturation current density for first diode J01 and series resistance Rs. The characterization methods suggested are expected to become more significant during co-firing of advanced solar cell structures like passivated emitter and rear contact (PERC) solar cells where surface modifications are done to improve the solar cell output parameters.