Impact of settlement time resolution on battery lifetime in self-regulating, hybridised solar photovoltaic and battery energy storage power plants

Power markets are currently transitioning to shorter settlement time periods, which may impact the health of batteries in hybridised solar photovoltaics (PV) and battery energy storage power plants. This study investigates how battery degradation is affected when the hybrid PV–battery energy storage power plant is operated to ensure firm delivery of power at an hourly basis, settled on various sub-hourly settlement times. A three-step modelling approach is presented to assess the system-level impacts of shortened settlement period on battery lifetime. First, synthetic PV AC power time series are generated from high-quality meteorological data. Second, a deterministic linear optimisation model with perfect foresight schedules battery charging and discharging to minimise imbalance volume of the generated synthetic PV profile, relative to an hourly power obligation. Finally, the resulting battery state-of-charge profiles are used as inputs to a semi-empirical lithium–ion degradation model to estimate capacity fade and lifetime. This framework is applied to a 10 MWp PV power plant coupled with 1 MWh, 2 MWh and 4 MWh batteries with storage durations from 0.25 h to 2 h, over settlement period time resolutions from 30 min to 1 min. Results show that shorter settlement periods increase cycling frequency and reduce battery lifetime, implying higher levelised cost of energy as markets adopt finer settlement resolution. These findings highlight the financial implications of high-resolution settlement for PV–battery asset owners and policy makers. • Hybrid PV battery plants operate in markets with shorter settlement times. • Methodology evaluates how shorter settlements affect battery life in hybrid systems. • Results suggest shorter settlement times decrease lithium ion battery lifetimes. • Results imply battery LCOE increases with finer market settlement resolution.