| | MAY 20258E ERGYTech ReviewIN MY OPINIONBESS AUXILIARY POWER By Pengfei Wang, Senior Manager, BESS Applied Technology, RWEAn Important but Often Overlooked Aspect of BESS Project Design and DevelopmentThe installation of battery energy storage systems (BESS) has been growing rapidly in the United States and worldwide since 2021, driven by the continuously falling cost of lithium-ion batteries and favorable government policies and incentives. While the industry is maturing quickly, there are still gaps because BESS remains a relatively new technology. One critical but often overlooked aspect of BESS project development is the technical requirements and financial implications of BESS auxiliary power.What Is BESS Auxiliary Load?In addition to the power required to charge its batteries, a BESS also requires power for its auxiliary loads. BESS auxiliary loads typically fall into the following three categories:· Control and communication equipment, such as the battery management system and network switches;· Thermal management systems, such as HVAC or chillers;· Fire safety systems, such as fire alarms, control panels and gas ventilation systems (if present).These auxiliary loads are essential for ensuring the safe and efficient operation of BESS projects. Therefore, providing a reliable power supply for these auxiliary loads is crucial.BESS Auxiliary Power Supply Circuit DesignMost BESS products on the market require an external power supply circuit for their auxiliary loads, although some have built-in circuits and do not need an external supply. When an external auxiliary power supply is required, project owners or their EPC (engineering, procurement and construction) contractors are typically responsible for designing, furnishing and installing the auxiliary power supply circuit. This includes auxiliary power transformers, switchboards and cables.Pengfei Wang is a Senior BESS Applied Technology Manager at RWE Clean Energy, where he provides technical support for BESS project development. His previous experience includes roles at Fluence Energy, General Electric and TNEI. Pengfei holds a PhD in Electrical Engineering from Newcastle University in the United Kingdom.Pengfei Wang
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