The segmental approximation in multijunction solar cells
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This document discusses the segmental approximation used to analyze dark and light I–V curves in multijunction solar cells, focusing on characteristics like open-circuit voltage and efficiency in relation to photogenerated current and sunlight concentration. It details an experimental procedure for parameter acquisition and analyzes the performance of a specific triple-junction solar cell, demonstrating that calculations match experimental data well at efficiency peak sunlight concentrations. Furthermore, it highlights the potential to obtain resistanceless I–V curves, which aid in characterizing losses within solar cells.
The segmental approximation in multijunction solar cells
- 1. THE SEGMENTAL APPROXIMATION IN MULTIJUNCTION SOLAR CELLS ABSTRACT The segmental approach has been considered to analyze dark and light I–V curves. The photovoltaic (PV) dependence of the open-circuit voltage (Voc ), the maximum power point voltage (Vm), the efficiency (η) on the photogenerated current (Jg ), or on the sunlight concentration ratio (X), are analyzed, as well as other photovoltaic characteristics of multijunction solar cells. The characteristics being analyzed are split into monoexponential (linear in the semilogarithmic scale) portions, each of which is characterized by a definite value of the ideality factor A and preexponential current J0 . The monoexponentiality ensures advantages, since at many steps of the analysis, one can use the analytical dependences instead of numerical methods. In this work, an experimental procedure for obtaining the necessary parameters has been proposed, and an analysis of GaInP/GaInAs/Ge triple-junction solar cell characteristics has been carried out. It has been shown that up to the sunlight concentration ratios, at which the efficiency maximum is achieved, the results of calculation of dark and light I–V curves by the segmental method fit well with the experimental data. An important consequence of this work is the feasibility of acquiring the resistanceless dark and light I–V curves, which can be used for obtaining the I–V curves characterizing the losses in the transport part of a solar cell.