Two-Stage Solar Photovoltaic-Based Stand-Alone Scheme Having Battery as Energy Storage Element for Rural Deployment

Solar photovoltaic (PV)-based stand-alone systems have evolved as a promising solution to the issue of electrification in areas where the grid is not available. The major challenges in designing such systems are as follows: 1) extraction of maximum power from the PV array; 2) protection of the battery from overcharge and overdischarge; 3) dc to ac conversion; and 4) provision for adequate voltage boosting. As multiple objectives are required to be satisfied, the existing schemes for stand-alone systems require a minimum of three converter stages, leading to considerable reduction in the reliability and efficiency of the system. In order to address this issue, a two-stage stand-alone scheme consisting of a novel transformer-coupled dual-input converter (TCDIC) followed by a conventional full-bridge inverter is proposed in this paper. The proposed TCDIC can realize maximum power point tracking and battery charge control while maintaining the proper voltage level at the load terminal. The small signal mathematical model of the TCDIC is derived. A suitable control strategy for the proposed TCDIC is devised. The operation of the scheme is verified by performing detailed simulation studies. A laboratory prototype of the scheme is developed. Detailed experimental validation of the scheme utilizing the laboratory prototype is carried out to confirm the viability of the scheme.