As part of research activities aimed at increasing the efficiency of concentrating photovoltaic (CPV) systems, the development of diagnostic techniques applied to photovoltaic devices plays a fundamental role. In fact, diagnostics allows us to obtain essential information for the evaluation of solar cells and their production process, both in terms of actual achievable performance and in terms of identifying any anomalies in the manufacturing processes of these photovoltaic devices.
The measurement of Spectral Response and Quantum Efficiency of multijunction (MJ) cells is one of the most important and complex measurements. It requires several steps which generally must be carried out by multiple operators.
During the activities for this project in 2021, a control system was implemented for the partial automation of the Spectral Response and Quantum Efficiency measurement system created by RSE. The control was carried out in the LabviewTM environment by means of various subprograms controlled by a supervision program.
The program provides for the setting of some measurement parameters and the control of various subsystems. Specifically, it regulates the light polarization supplied to the cell, controls the monochromator for the selection of the measurement wavelength, turns the light sources on or off and controls the positioning of the different optical filters mounted on a filter wheel.
A new calibration system has also been introduced based on the use of only two calibrated photodiodes with sensitivity in partially overlapping spectral bands.
The instrument was tested by carrying out some preliminary measurements of Spectral Response and Quantum Efficiency of four-junction photovoltaic cells.