A CMOS-Based Energy Harvesting Approach for Laterally-Arrayed Multi-Bandgap Concentrated Photovoltaic Systems

This paper presents an energy harvesting approach for a concentrated photovoltaics (CPV) system based on cell-block-level integrated CMOS converters. The CPV system, built upon the Laterally-Arrayed Multi-Bandgap (LAMB) cell structure, is a potentially higher-efficiency and lower-cost alternative to traditional tandem-based systems. The cells within a sub-module block are connected for approximate voltage matching, and a CMOS-based multi-input single-output (MISO) buck converter harvests and combines the energy while performing maximum power point tracking (MPPT) locally. First, a comparison of modeled performances achievable with traditional tandem CPV and LAMB CPV with a MISO converter is presented using day-long outdoor measured solar spectrum. The model predicts on average >19% more energy can be extracted from LAMB modules on a typical day. Then, a prototype miniaturized MISO dc-dc converter operating at 10MHz is developed in a 130nm CMOS process. For 45-160mW power levels, the prototype converter achieves >92% nominal and >95% peak efficiency in a small form factor designed to fit within available space in a LAMB PV cell block. The results demonstrate the potential of the LAMB CPV architecture for enhanced solar energy capture.