Test Methodology for Residential Stationary Battery Energy Storage Systems

Abstract

Abstract This thesis proposes a compressed test sequence designed to characterize and assess the annual performance of a stationary battery energy storage system integrated with a residential solar PV system, within a short testing duration. The approach followed consists of studying annual system profiles (load demand and irradiance profiles) obtained from historical measurements, through which four representative days that best reflect the system’s annual operational patterns were systematically selected. The dimensioning aspect for the battery energy storage system, PV and power electronic converter systems, along with their relationship between the energy and power capacities of the battery, was studied through a market survey. The criteria utilized in the selection of the representative days assess the relative error between sums and averages values of the annual and representative day system profiles. These representative days serve as the basis for the compressed test sequence. To evaluate the performance of the system, the relevant performance metrics were evaluated. These include conversion efficiencies based on the energy flow path in the system, battery storage capacity, and round-trip efficiency. The results of the market survey indicated that a typical energy-to-power ratio ranging between 2–3.5 kWh/kWp, with an average battery size of around 5–10 kWh for SBESS coupled with a PV system in residential applications. The survey also highlighted that the size of the SBESS is influenced not only by the size of the PV system, but also by the power electronics converter (PEC) capacity and the system topology connection applied in the system. Using flow-duration curves, the results show how closely the selected representative days align with the annual system profiles. For load demand, the relative errors between the daily and annual averages and sums were 0.1% and 1.6%, respectively. The irradiance profile showed slightly higher deviations, with relative errors of 3.0% for averages and 4.7% for sums between daily and annual values, respectively. This highlights the impact of transitional boundaries between seasons, where the largest deviations in seasonal profiles are observed. The proposed test sequence followed a 4-day sequence, with two additional days reserved for reconditioning and rebalancing the battery’s state of charge (SOC). The Battery Management System (BMS) of the SBESS regulates the battery energy flow on the basis of the selected representative day profiles. In this way, the test sequence allows the battery to be cycled according to the load demand and the PV throughput, following the self-consumption and self-sufficiency control strategy commonly used in residential applications.