Substation battery banks (SBB) in electrical substations participate in black start recovery processes and provide essential back-up power supply for protection, control, telecommunications, and lighting. With stringent limitations on space and increasing requirements for safety and reliability, potential battery sizing optimisation opportunities may be possible to enable reliable, secure, space, time and cost-effective substation energy storage. Battery efficiency with optimal use supports the energy system transition by supporting evolving substation loads requiring appropriate scaling design that avoids costs in either oversizing initial banks or reinstalling entirely new banks. This project considers existing and future battery banks improvements to best practice, better chemistries, and online monitoring techniques with expected benefits in reducing carbon footprint and maintenance costs whilst informing correct & adaptive battery sizing.
Benefits
NGET’s capital & operational budget shows that £54m investment is expected over 10 years around LVAC systems, with approximately 600 battery replacements in RIIO-T2/3. The assumption for the benefit estimation is that this project would harvest 5% savings of the planned investment. The innovative case is envisaged to result in £20,000 footprint savings per each new substation. This yields potential savings/NPV benefits over the next 10 years of approximately £3.240m.
Learnings
Outcomes
- The project improved understanding of battery operation, performance and asset life management by assessing charging and discharging practices, battery life expectancy and opportunities for life extension. The findings reinforced the importance of effective battery management strategies in maintaining reliable backup power supplies, reducing premature degradation and supporting more informed replacement decisions.
- The project established a framework for advanced battery condition monitoring by identifying the key parameters required for battery health assessment, including voltage, current, impedance and temperature. This demonstrated the value of continuous monitoring in supporting maintenance decisions and improving visibility of battery condition throughout its operational life.
- The project successfully developed, tested and demonstrated an innovative online battery monitoring system. The computerised monitoring system was validated in the laboratory and subsequently deployed on an operational transmission substation battery bank, where it successfully captured battery performance data under both steady-state and transient operating conditions.
- The project demonstrated the feasibility of online battery bank monitoring and established a foundation for gathering long-term operational data to improve understanding of battery duty cycles, utilisation patterns and state of health. This provides a pathway towards future optimisation of battery sizing, maintenance practices and replacement strategies across the transmission network.
- Despite several months of delay arising from site access and deployment constraints, the project successfully progressed the original concept from TRL 3 to TRL 5, achieving both proof-of-concept and system demonstrator stages. The project has delivered a unique battery condition monitoring solution suitable for online application within electricity transmission substations.
- A deployment methodology, including supporting Risk Assessments and Method Statements (RAMS), was developed to facilitate safe installation and operation in a live transmission environment. In addition, a follow-on deployment concept was identified to enable easier installation, automated alarms and enhanced assessment of battery state of health and operational duty throughout service life, supporting improved resilience, reliability and cost-effective asset management.
- The detailed design and implementation information relating to the condition monitoring system contains innovative intellectual property developed through the project and should not be made publicly available, as it may support future commercial and operational exploitation
Total NIA Expenditure on project
The project includes £562,059 of milestone expenditure, covering the delivery of ten technical milestones ranging from the initial literature review through to the final options and recommendations report. In addition, the project includes £48,230 of internal costs and £63,000 of indirect costs, resulting in a total project budget of £673,299. The total cost is slightly lower than the PEA total budget that was approved on the Smarter Network Portal in June 2026. Although the final project expenditure was slightly lower than the budget approved in the PEA, all project objectives and deliverables were successfully completed.
Lessons Learnt
- Site access and operational constraints should be considered early in project planning. Projects that transition from laboratory-based development to in-service testing can experience significant delays due to the time required to obtain site access approvals, outage planning, safety clearances, and coordination with operational teams. Future projects should include additional contingency within programme timelines to accommodate these practical constraints, particularly when demonstrations are dependent on access to critical transmission assets.
- Data accessibility and remote monitoring requirements are increasingly influenced by cybersecurity considerations. While remote condition monitoring offers significant operational benefits, implementation can be challenging due to cybersecurity requirements, network access restrictions, and IT system approval processes. Future demonstrator projects should engage with cybersecurity and digital teams at an early stage to ensure that data access, communications architecture, and security requirements are understood and incorporated into the project plan from the outset.
- Early validation of monitoring and data acquisition equipment is essential. The project identified limitations in the initially selected data acquisition hardware when deployed on a live 110 V floating battery system. Although a suitable isolation solution was successfully developed, earlier testing against representative field conditions could have reduced development time and deployment risks.
- Industry collaboration provides valuable technical insight. Engagement with battery manufacturers, monitoring specialists, and industry experts helped validate the project approach and provided useful perspectives on emerging battery technologies, condition monitoring techniques, and future asset management practices. Similar collaborative approaches should be encouraged in future innovation projects.
Dissemination
- The project and its emerging findings were discussed with battery manufacturers, monitoring solution providers, and industry experts at the National Industrial Battery Seminar conferences (NiBS) in 2024 and 2025. In addition, an overview of the project and its objectives was presented at NiBS 2025, enabling engagement with key stakeholders and facilitating knowledge exchange on battery technologies, condition monitoring, and future substation energy storage solutions.
- Project outcomes were disseminated through the Ultra High Voltage Electrical Networks (UHVnet) Conference 2026, where a poster entitled “Monitoring System for Battery Bank for LV Auxiliary DC Network at Transmission Substation” was presented during the poster session on 21 May 2026 [‘Monitoring System for Battery Bank for LV Auxiliary DC Network at Transmission Substation’, Abhishek Kumar, Manu Haddad, Liana Cipcigan, Andrew Ridley, Aisha Ali, Tinashe Chikohora, and Christopher Stone, May 2026, Birmingham, UK]
- A draft paper outlining the survey findings on key parameters for battery chemistry selection is currently being prepared for submission to the UPEC 2026 conference, to be held in Italy in August–September 2026 (in progress
