Optimal design and dispatch of a hybrid microgrid system capturing battery fade

Microgrids provide power to remote communities and at operational sites that are not connected to a grid. We consider such a microgrid that consists of batteries, photovoltaics, and diesel generators, and optimize the components it comprises and a corresponding dispatch strategy at hourly fidelity so as to minimize procurement, operations and maintenance, and fuel costs. The system is governed by constraints such as meeting demand and adhering to component interoperability and capability. Our contribution lies in the introduction to this optimization model of a set of constraints that incorporates capacity fade of a battery and temperature effects. We show, using data from a forward operating base and solving the corresponding instances for a time horizon of 8760h, that higher temperatures decrease resistance, leading to better round-trip energy efficiency, but at the same time increase capacity fade of the battery, resulting in a higher overall operating cost. In some cases, the procurement strategy is robust to the fade of the battery, but fade can influence battery state of charge and power output as the available battery capacity degrades over time and with use.