Multifunctional module lithium-ion storage and photovoltaic conversion of solar energy

A large part of photovoltaic research is dedicated to developing innovative integration technology for the module. Now the use of a storage function in such intermittent power supply systems is crucial in order to get better adequacy between the peaks of energetic consumption and production. The integration degree of photovoltaic systems will be improved if all the components: panel, battery, converters, electronic control unit, cablings can be combined in a compact single unit. Different battery technologies are currently used with photovoltaic systems along with some of the charging and discharging techniques that are available. Lithium-ion technology appears to be the best candidate because of its high energetic efficiency, high specific energy density, deep discharge ability, its long cycling life and its possible different shapes (cylindrical or prismatic styles) to obtain an integrated design. To optimize the battery performance, different conditions are required and achieved by control sub-systems, integrated into battery and module construction. The electronic management system presented in this paper aims to optimize the use of the battery making the overall system more reliable and cost effective. On the one hand, a research algorithm of the optimal power to charge and discharge an advanced lithium-ion battery for photovoltaic application is necessary to obtain an optimum electronic management system. On the other hand, a Maximum Power Point Tracking is also incorporated into the electronic control unit, to optimize the solar array production under varying atmospheric conditions. This paper will describe a new concept of an integrated multifunctional module using lithium-ion batteries and new control algorithms.