Batteryless 275mV startup single-cell photovoltaic energy harvesting system for alleviating shading effect

Without any batteries, a low input voltage converter is presented for a single-cell (SC) photovoltaic (PV) energy harvesting to alleviate the energy degradation due to shading effect. The proposed low voltage startup (LVS) circuit with low input voltage of 275 mV and less than 840 ms startup time achieves high voltage conversion ratio to supply a high accuracy bandgap reference. Experimental results show the maximum power throughput is up to 6 mW and the quiescent power is less than 650 μW with integrated two buck-boost converters and two boost converters. The peak efficiency of the boost converter can be up to 75.8% for ultra-low voltage hearing aid systems.