A Low Power Photo-Voltaic Battery Charger With Improved Reliability and Functionality to Reduce Shading Effect

Solar energy harvesters have been used lately as a source for battery chargers in a low power scheme. These energy harvesting/charging 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 article 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/18 mW charger was built and successfully tested with 87.3% heavily sourced efficiency retained.