A Low Power Photo-Voltaic Battery Charger with Improved Reliability and Energy Recovery to Reduce Shading Effect

Micro-solar energy harvesting systems can operate efficiently at relatively high threshold luminance, and they exhibit 0% efficiency below threshold luminance or at strong shading. The objective of this paper is to introduce a new topology that improves the charge efficiency, functionality, sensitivity, and reliability of the Photo-Voltaic (PV) solar chargers during strong overcast while employing minimum hardware. The proposed topology responds to a wide range of solar irradiation and functions as an efficient charger with an improved battery charging current for slow charge topology at strong shading. It employs a boost converter with a second inductor and exploits the non-linearity of the PV characteristics of a solar cell to reduce power loss. To verify the proposed topology, a prototype, 1.4V/18mA charger, was built and successfully tested with 87.3% heavily sourced efficiency retained.