Improved Performance of the Integrated Power Supplies Based on Cu₂ZnSn(S,Se)₄ Solar Cells

Solar energy is an environmental friendly and sustainable energy source to solve the energy shortage and environmental pollution problems nowadays. Integrated power supply shows great potential in utilizing solar energy which converts solar energy into electrical energy. Integrated power supplies with optimized structures are constructed with Cu2ZnSn(S,Se)(4) solar cells and LiFePO4 (LFP) lithium-ion batteries for the first time. The matching of integrated power supply is investigated in detail for a better understanding and design of highly efficient integrated power supply. In the results, it is shown that the open-circuit voltage of solar cells has a significant influence on the efficiencies of integrated power supply. Apart from that, the calculation of average power coupling factor is proved to be an effective method to evaluate the difference between the actual and ideal working condition of the integrated power supply. As to current matching of integrated power supply, it is emphasized that the capacities of LFP coin cells should be designed within a normal range where the photo-charging time and the characteristic of energy-storage batteries need to be considered simultaneously.