Energy storage dispatch is the real-time or scheduled control of a battery energy storage system (BESS) to decide when to charge, when to discharge, and at what power level. In EV charging sites, dispatch is used to reduce costs, limit peak demand, support fleet readiness, increase renewable self-consumption, and maintain site resilience under grid constraints.
What Is Energy Storage Dispatch?
Dispatch is the “operating strategy” of a storage system, executed by an Energy Management System (EMS), microgrid controller, or site energy controller.
– Charge the battery when energy is cheap or abundant (off-peak tariffs, high solar output)
– Discharge the battery when site demand is high or energy is expensive
– Maintain minimum reserves for backup or operational reliability (if required)
– Respect system constraints such as state-of-charge limits, power limits, and thermal limits
Dispatch can be automated (rule-based or optimization-based) and adjusted continuously as conditions change.
Why Energy Storage Dispatch Matters for EV Charging
EV charging can create large peaks and unpredictable load patterns, especially at depots and high-utilization sites.
– Enables more chargers without immediate grid upgrades by providing buffered power
– Reduces demand charges by shaving peaks during simultaneous charging sessions
– Improves charging availability when grid import limits are tight
– Increases use of onsite solar by storing surplus for later vehicle charging
– Supports energy arbitrage where time-based pricing or dynamic markets exist
– Improves resilience when storage is configured to support critical charging during outages (where permitted)
Common Dispatch Objectives for Charging Sites
– Peak shaving: discharge during the highest site demand windows to reduce maximum kW
– Time-of-use shifting: charge off-peak, discharge during peak price periods
– Solar self-consumption: store midday PV surplus and use it during evening charging
– Fleet readiness priority: ensure vehicles reach required SoC by departure time while minimizing cost
– Import cap enforcement: keep site import below a contractual or technical limit
– Backup reserve management: preserve a state-of-charge floor for critical operations
How Energy Storage Dispatch Works
Dispatch decisions typically use a combination of data inputs and control logic.
– Site import/export measurement from meters (kW)
– EV charging demand from CPMS/chargers (current sessions and predicted demand)
– Battery constraints: SoC, maximum charge/discharge power, efficiency, temperature
– Tariffs, demand charge rules, or price signals
– PV generation data and forecasts (if integrated)
– Optional constraints: export not allowed, noise/operational policies, grid service commitments
The EMS calculates setpoints and sends commands to the inverter/BESS controller, often updating every few seconds to minutes.
Dispatch Strategies: Rule-Based vs Optimization-Based
– Rule-based dispatch: simple triggers (if site load > X kW, discharge; if PV surplus, charge)
– Optimization-based dispatch: uses forecasts and cost models to decide the best schedule over hours or days
Rule-based strategies are easier to implement; optimization-based dispatch often delivers better economics, especially with complex tariffs and fleet schedules.
Key Metrics to Monitor
– Peak demand reduction (kW) and number of peak events
– Battery throughput (kWh cycled) and round-trip efficiency
– Cost savings from TOU shifting and demand charge reduction
– Impact on charger availability and fleet readiness
– Battery SoC profile and reserve compliance
– Dispatch-induced export events (if export is constrained)
Limitations to Consider
– Battery cycling creates degradation; dispatch must account for lifecycle cost per kWh shifted
– Poor forecasting can increase cost or reduce readiness if the battery is used at the wrong time
– Export restrictions and grid connection terms can limit dispatch options
– Safety, permitting, and compliance requirements apply to BESS installations
– Integration complexity increases when coordinating BESS with chargers, PV, and building loads
Related Glossary Terms
Battery Energy Storage System (BESS)
Energy Management System (EMS)
Peak Shaving
Demand Charges
Energy Arbitrage
Renewable Integration
Load Management
Depot Energy Optimization