A Hybrid Battery / Ultracapacitor Energy Storage Solution for PV Systems

With increased efficiency and reduced initial investment, photovoltaic (PV) systems have become very popular. Installed capacities in every part of the globe are increasing dramatically annually, but will soon be capped due to grid integration limitations. This is mostly due to uncertainty in the generation capacity due to the unpredictable nature of renewable energy resources. This complicates integration with traditional generation dispatch schemes. The solution is the deployment of energy storage solutions. Storage technologies have exponentially improved over the years, but performance and price are still a limiting factor. Ultracapacitor manufacturing has matured, with capacitance values reaching thousands of Farads. They may be charged with high current resulting in high power and energy density. The purpose of this study is to quantify the improvement in the performance of a battery system with the addition of an ultracapacitor as an auxiliary energy storage device for solar PV applications. The improvement in performance is demonstrated through mathematical modelling and verified with simulation.