Charging Strategy for a Residential Battery Storage System using Fuzzy Logic Controller

The decrease of PV feed-in tariff and the progress on battery manufacture has significantly fostered the application for residential storage system. In order to save expense by increasing self-consumption rate, it is necessary to achieve an efficient usage of battery by developing a power control strategy in a household grid-connected PV-storage system. The strategy is also supposed to address potential curtailment power loss derived from surplus solar generation under high irradiance and strict feed-in limitation since it is a waste issue and results in avoidable energy retail cost. The challenge lies on managing surplus generation to battery and grid power flow, ideally without relying on error-prone forecasts for both load and generation in a PV-storage system. This paper proposes a fuzzy logic controller (FLC) based charging method to manage surplus power in order to avoid the waste of curtailment power loss and achieve the aim of minimum cost by battery utilization. Comparisons on curtailment losses, energy transfer via the grid and resulting savings achieved by battery installation are conducted and compared to three other reference methods, namely a direct charging / discharging strategy (“greedy”), a formerly investigated “feed-in damping” strategy and a “perfect foresight” strategy with forecast on load and generation. Using this easy implementable fuzzy logic method without forecast on generation as well as consumption power, the minimum total cost can be achieved by the proposed FLC method compared to the analyzed methods without the knowledge of power profiles in advance.