A logic-based geometrical model for the next day operation of PV-battery systems

•We use a graphical method to optimize the use of batteries with PV panels.•The method relies on next day forecasts of output and load, minimising power costs.•The method is applied to Sydney homes using different power tariffs.•The control system should be different for time-of-use and flat electricity tariffs.

This article presents a new control model for the optimal next day management of a PV-battery system using a geometrical analysis method under two electricity tariff schemes. The method is visual, simple and reduces calculation times by determining the control scheme only once a day, using 24-h forecasting of PV output and demand. The optimization goal of this method is to minimize the customer’s daily expenditure on electricity from the grid. The cases studied in this work validate the effectiveness of this geometrical method which would be applicable in many countries with different tariff mechanisms. From a comparison of the control model under two tariffs, the results show that under a flat retail tariff (ReT), the battery needs only to store the surplus PV energy for later use, but under a Time-of-Use (ToU) ReT, the battery controller should optimize the battery state of charge according to the level of demand during peak and shoulder times.

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