Time-of-Use (ToU) tariffs are electricity pricing schedules where the cost of power changes depending on the time of day, day of week, and sometimes season. In EV charging, ToU tariffs influence what the site pays for electricity and/or what drivers are billed—encouraging charging when the grid is less loaded and energy is cheaper (off-peak) and discouraging charging during expensive peak periods.
Why ToU Tariffs Matter in EV Charging
ToU tariffs are a key lever for both cost control and grid-friendly charging:
– Reduce energy costs by shifting charging into off-peak windows
– Lower peak demand and help comply with a maximum site demand limit
– Improve utilization of existing grid connection capacity without upgrades
– Support managed charging for fleets and workplaces
– Help smooth local grid load and reduce congestion risk
For depots and multi-tenant buildings, ToU tariffs can significantly improve operating economics.
How ToU Tariffs Work
A typical ToU tariff defines:
– Time blocks (peak, shoulder, off-peak)
– A price for each block (usually €/kWh at the electricity supply level)
– Special schedules for weekends and holidays
– Seasonal adjustments (winter vs summer schedules in some markets)
– Sometimes demand charges or capacity-based components
Charging platforms can reflect ToU either as internal cost optimization (operator-side) or as customer-facing ToU pricing.
Common ToU Tariff Structures
– Peak / off-peak
Two-rate structure for simple pricing and clear incentives
– Peak / shoulder / off-peak
Three-rate structure for more detailed shaping of demand
– Night-rate focus
Very low night pricing to encourage overnight fleet and residential charging
– Dynamic time schedules
Utility-defined time blocks that change periodically (still schedule-based rather than real-time wholesale pricing)
Operator Cost ToU vs Customer Billing ToU
Two ToU layers may exist:
– Operator ToU: the site’s electricity procurement cost varies by time
– Customer ToU: the driver price varies by time to influence behavior
Operators may use ToU internally with load management even if public pricing stays flat, to avoid confusing customers.
Practical Considerations for Deployments
– Best results occur where dwell time is long (fleet depots, workplaces, residential garages)
– Requires automation or behavior change to shift load reliably
– ToU configuration must handle time zones and daylight-saving shifts correctly
– Clear communication and display reduce billing disputes
– ToU should align with operational rules like idle fee policy and bay turnover goals
Common Pitfalls
– Over-complex time blocks that users don’t understand
– Not accounting for site constraints, leading to many vehicles starting simultaneously off-peak
– Misconfigured tariff schedules causing incorrect billing
– Roaming price inconsistency where partners don’t mirror your ToU logic
– Confusing ToU tariffs (energy pricing) with time-based billing (€/minute charging)
Best Practices
– Keep ToU windows simple for public users; use advanced scheduling for fleets
– Pair ToU with time-of-use optimization and managed charging
– Enforce site caps through load management to avoid overloads and thermal trips
– Track KPIs: off-peak share, peak demand reduction, cost savings, readiness exceptions
– Provide transparent receipts showing applied tariff windows when ToU is customer-facing
Related Glossary Terms
Time-of-Use Pricing
Time-of-Use Optimization
Off-peak Charging
Peak Demand
Peak Shaving
Managed Charging
Load Management
Maximum Site Demand Limit
Tariff Structures
Idle Fee Policy