Stationary battery storage is a fixed (non-vehicle) battery system installed at a site to store electricity and discharge it when needed. In EV charging, stationary batteries are used to reduce peak demand, support charging during grid constraints, and improve energy cost control by shifting energy use to cheaper or cleaner periods.
Stationary battery storage is commonly deployed as a Battery Energy Storage System (BESS), typically using lithium-ion chemistry (such as LFP), integrated with power electronics, protection, and an energy management controller.
Why Stationary Battery Storage Matters for EV Charging
EV charging can create high and variable electrical demand—especially in multi-charger sites and fleet depots. Stationary batteries help sites:
– Reduce peak demand charges and avoid exceeding a maximum site demand limit
– Enable more charge points without immediate grid upgrades (grid reinforcement deferral)
– Improve charger uptime and continuity during short grid events (design-dependent)
– Support scalable rollout by buffering power for future expansion
– Increase use of on-site renewables by storing solar PV for later charging
For commercial and public charging, stationary storage can be the difference between a “few chargers now” and a scalable, high-utilization site.
How Stationary Battery Storage Works in Charging Sites
A typical charging + storage setup works like this:
– The battery charges from the grid during low-demand or low-tariff periods
– The battery can also charge from on-site solar PV where available
– During high-demand periods, the battery discharges to support EV chargers
– An energy management system (EMS) monitors site load, tariffs, and limits
– Power is balanced to keep the site within connection constraints and optimize cost
Depending on design, the battery may support the whole site load or only the EV chargers.
Common Use Cases
Stationary battery storage is widely used for:
– Fleet depots with clustered charging and strict operational windows
– Public charging hubs where peak demand charges are high
– Workplaces and mixed-use developments with limited grid capacity
– Sites with expensive or slow grid upgrade timelines
– Locations with solar PV seeking higher self-consumption
– Temporary or phased installations where demand grows over time
Key Benefits for Operators and Site Owners
– Lower electricity costs through peak shaving and tariff optimization
– Better utilization of existing grid connection capacity
– Increased flexibility to add chargers without immediate upstream upgrades
– Improved resilience and stability in constrained networks (design-dependent)
– Enhanced sustainability outcomes when paired with renewables
Limitations and Considerations
Stationary storage adds complexity and must be engineered carefully:
– Additional CAPEX, space requirements, and permitting considerations
– Battery sizing must match charging profiles, dwell times, and peak patterns
– Thermal management and safety systems are critical for reliable operation
– Round-trip losses reduce net energy efficiency compared to direct grid supply
– Control strategy matters: poor tuning can shift peaks rather than reduce them
Integration with Managed Charging and Load Management
Stationary storage is most effective when combined with:
– Load management to allocate power dynamically across chargers
– Managed charging schedules for fleets (charge-by-departure planning)
– Peak demand profiling to correctly size the battery and PCS
– Grid monitoring to avoid overload events and comply with site limits
Together, these tools increase site throughput while controlling demand and operating cost.
Related Glossary Terms
On-site Battery Buffering
Load Management
Managed Charging
Peak Shaving
Peak Demand
Maximum Site Demand Limit
On-site Solar PV
Grid Capacity Assessment