Load shifting is the practice of moving electricity consumption from one time period to another—typically from peak-demand or high-price hours to off-peak, lower-cost periods. In EV charging, load shifting means scheduling or controlling charging sessions so energy is delivered when the grid is less constrained and electricity is cheaper, while still meeting driver or fleet readiness requirements.
What Is Load Shifting?
Load shifting changes when energy is used without necessarily reducing total energy consumption. For EV charging, this can involve:
– Delaying charging start times to off-peak hours
– Reducing charging during peak windows and resuming later
– Scheduling charging to align with low tariffs or low site load periods
– Coordinating charging to match on-site renewable generation (e.g., midday solar)
Load shifting is often implemented through smart charging controls in a CPMS or EMS.
Why Load Shifting Matters in EV Charging Infrastructure
EV charging demand often overlaps with building peaks (morning arrival, evening return). Load shifting helps:
– Lower electricity costs by avoiding peak tariffs and demand charges
– Reduce stress on the grid during congestion periods
– Increase the number of chargers a site can support within a site power limit
– Improve sustainability by charging when grid carbon intensity is lower (where available)
For fleets, load shifting can reduce operating costs while maintaining vehicle availability.
How Load Shifting Works in EV Charging
Load shifting typically relies on a combination of rules, data, and control:
– Time-of-use tariff windows (peak / shoulder / off-peak)
– Site load limits and headroom from load measurement
– User constraints (departure time, minimum energy needed)
– Charger control via dynamic current or power limits (often using OCPP)
Common approaches:
– Time-based schedules: charge only during defined hours
– Smart scheduling: distribute energy across many EVs overnight to meet deadlines
– Adaptive shifting: reduce charging when building load rises and increase when it falls
– Solar-aware shifting: prioritize charging when PV output is high
Load Shifting vs Load Shedding vs Load Curtailment
These terms are related but not the same:
– Load shifting: move charging to a different time window (planful control)
– Load curtailment: reduce charging power to stay within limits (may be temporary)
– Load shedding: stop or disconnect loads to prevent overload (protective action)
Load shifting is usually a proactive optimization strategy, while shedding is typically a last-resort safeguard.
Key Benefits of Load Shifting
– Lower energy costs and reduced peak-demand exposure
– Improved grid friendliness and reduced congestion impact
– Better utilization of existing electrical infrastructure
– Supports fleet readiness without increasing connection capacity
– Enables renewable-aligned charging strategies
Practical Considerations and Limitations
Effective load shifting requires coordination and clear constraints:
– Drivers or fleets must accept delayed charging if readiness targets are still met
– Sites need reliable time schedules and tariff data
– Minimum charging current limits must be respected to avoid session drops
– Communication resilience and safe fallback behavior are important
– Public charging sites with short dwell times have less flexibility than destination or fleet sites
Load shifting works best where vehicles remain parked for hours, such as workplaces, residential parking, and fleet depots.
Related Glossary Terms
Smart charging
Charging schedule
Load management
Load balancing
Load curtailment
Load shedding
Peak shaving
Demand response
Site power limit
Energy management system (EMS)