Battery load shifting is the use of a battery system—most commonly a Battery Energy Storage System (BESS)—to move electricity consumption from one time period to another. In EV charging, load shifting stores energy when it is cheaper or when there is spare grid capacity, then supplies that energy later to support charging during high-demand or high-tariff periods.
What Is Battery Load Shifting?
Battery load shifting changes the timing of when electricity is imported from the grid:
– The battery charges during off-peak hours or when renewable generation is available
– The battery discharges later to supply EV chargers and reduce grid import
– The site’s peak demand is reduced, and charging becomes more cost-efficient
This is a core function of many smart energy strategies for charging hubs, fleet depots, and commercial sites.
Why Battery Load Shifting Matters in EV Infrastructure
EV charging demand often peaks at predictable times (end of workday, overnight fleet charging, retail peak hours). Without load shifting, sites may face:
– High demand charges and expensive peak tariffs
– Limited available import capacity restricting how many EVs can charge
– Grid upgrade requirements to support short-duration peaks
– Higher risk of overload trips in constrained installations
Battery load shifting helps site owners and CPOs:
– Reduce energy costs under time-of-use tariffs
– Increase effective charging capacity without increasing the grid connection
– Improve ROI for charging projects by lowering operating expenses
– Support more predictable site operation and better availability
How Battery Load Shifting Works
A typical load shifting setup includes a BESS, an inverter/PCS, metering, and an energy management system (EMS):
– The EMS monitors tariffs, site load, and charger demand
– The battery charges when electricity is cheap or when spare headroom exists
– During peak periods, the battery discharges to supply part of the EV load
– The EMS caps grid import to a predefined threshold to avoid peak charges
– Chargers may be coordinated with load management and power limits
Load shifting is often combined with:
– Peak shaving (controlling the maximum site demand)
– Power boosting (short bursts of higher charger output)
– Renewable shifting (storing solar PV energy for later charging)
Typical Use Cases
– Fleet depots charging many vehicles overnight while avoiding a high peak at start-of-shift plug-in
– Retail and workplace sites with time-of-use tariffs and demand charges
– Public charging hubs where multiple sessions overlap and create peaks
– Sites with solar PV that want to charge EVs later when the sun is gone
– Locations where grid reinforcement is delayed but charging demand is growing
Key Benefits of Battery Load Shifting
– Lower electricity bills by shifting charging supply to cheaper periods
– Reduced demand peaks and improved compliance with import limits
– More chargers can operate on constrained grid connections
– Better utilization and fewer overload-related shutdowns
– Improved sustainability outcomes when aligned with renewable generation
– Increased resilience when combined with backup-capable system design
Limitations to Consider
– Battery sizing must match the site’s charging profile to deliver meaningful savings
– Battery degradation and cycling costs must be included in the business case
– Round-trip efficiency losses reduce the net energy returned
– Tariff structures vary widely; savings depend on local pricing and demand charges
– Permitting, safety, and fire protection requirements can add complexity
– Load shifting cannot replace grid upgrades if sustained high power is needed continuously
Related Glossary Terms
Battery Energy Storage System (BESS)
Energy Management System (EMS)
Peak Shaving
Power Boosting
Available Import Capacity
Smart Charging
Dynamic Load Balancing
Battery Buffer Storage
Microgrid
Backup Power Operation