All-in-One Photovoltaic Power System: Features and Challenges Involved in Cell-Level Power Conversion in ac Solar Cells

Power converters constructed from discrete components are difficult to mass produce, and their installation requires a significant labor cost for the proper interconnection among the panel, inverter, and grid. Several critical applications, such as portable power stations (for use on a battlefield or scientific expedition), will require key attributes from a photovoltaic (PV)-based power system, such as modularity, high reliability, and quick set-up time. Therefore, a paradigm shift in the design of the entire PV power system is needed to mitigate this need. To increase the converter reliability and portability, the active and passive elements of a power converter [especially capacitors and active switches such as metal-oxide-semiconductor field-effect transistors (MOSFETs), junction gate field-effect transistors (JFETs), or insulated-gate bipolar transistors (IGBTs)] could be embedded on the same substrate material used for fabricating the p-n junctions in the PV panel. To the authors' knowledge, there is no prior work in cell-level power conversion with embedded converters, and therefore this project idea could be considered "outside the box." A novel fabrication process along with experimental results are presented in this article, demonstrating the integration of PV cells and major components needed to build a power converter on the same substrate/wafer. Because of the cell-level power conversion, PV panels constructed from these cells are likely to be immune to partial shading and hot-spot effects. In addition, the effect of light exposure on converter switches has been analyzed to understand the converter behavior at various illumination levels. Simulation and experimental results have been provided to support this analysis. In addition to process-related challenges and issues, the justification of this integration is explained by achieving higher reliability, portability and complete modular construction for PV-based energy harvesting units.