Off-Grid Portable Photovoltaic System Operating At Low Power Conditions

A new approach to portable photo-voltaic systems which described in this paper is of very low power (5W) and main purpose is for recharging or powering small portable electronics devices. The objects of this study are: i) the optimization of photo-voltaic cells connection with regard to portable conditions; a nonstandard topology is adopted, to compensate shadowing or nonoptimal orientation; ii) the introduction of a topology for battery and DC/DC converter, in which the battery voltage is optimized for photo-voltaic operation and a buck-boost converter can provide any voltage to the load. A good efficiency is achieved also in marginal condition of illumination (0.1W). A series of measurements have been performed in a real-life situation, and the system has been characterized. The efficiency of the proposed system has been compared with a conventional system, in the same operating conditions.