Smart charging schedules

How vehicle, chargepoint and supplier schedules coordinate charging windows, departure targets and electrical limits.

A smart charging schedule decides when an EV may charge and, in some systems, varies the power so the vehicle reaches a target by a departure time. It can respond to a tariff, household load, solar generation or a remote flexibility service.

Reliable scheduling needs one clear source of control. The vehicle, chargepoint and energy supplier can each have a timer, and overlapping rules are a common reason a car does not charge when expected.

Choose the primary scheduler

The main options are:

vehicle schedule, which travels with the car but may not know the home’s load or tariff integration
chargepoint schedule, which can use site metering and works across compatible vehicles
supplier or third-party control, which may optimise against a tariff or flexibility instruction
home-energy management, which coordinates PV, battery, heat and EV demand

Use one as the primary controller and disable or widen conflicting windows elsewhere. Keep any safety and load-management controls active regardless of who schedules the energy.

Window control and departure control

A fixed window simply permits charging between chosen times. The car normally draws up to the available limit until its own charge target is reached.

A departure-based controller works backwards from the requested energy or vehicle state of charge and the time the car must be ready. It may start later, pause or vary power. Its plan depends on access to reliable vehicle data; when that data is unavailable, it may use an estimate or fallback.

For a critical journey, leave a sensible contingency and confirm the car is actually charging. An app plan is not stored energy.

The Great Britain smart-chargepoint rules

As at 22 July 2026, the EVs (Smart Charge Points) Regulations 2021 apply to covered private domestic and workplace chargepoints sold in England, Scotland and Wales. They require smart functionality, supplier interoperability, a user interface, metering information, continued charging capability after communications loss, cyber-security measures and a randomised-delay function.

Covered chargepoints are supplied with default off-peak hours, but the owner must be able to accept, remove or change them. The regulation’s default is not a requirement that every driver use those hours or that they match the driver’s tariff.

Public chargepoints and non-smart portable cables follow different regulatory scopes.

Randomised delay

If many vehicles begin charging at exactly the same scheduled time, the step in electricity demand can be large. Randomised delay spreads starts and changes over a short period.

This means a compliant chargepoint may not begin at the exact displayed minute. The owner can change or override settings within the product and regulations, but should allow for the delay when the available window is tight.

A much longer failure to start is unlikely to be explained by randomisation alone and should prompt a schedule and fault check.

Calculate whether the window is long enough

The required duration depends on energy needed at the battery and the power the vehicle actually accepts. Conversion loss means electricity drawn at the meter is greater than the increase in stored battery energy.

Use:

approximate charging time = energy required ÷ sustained charging power

Then allow for loss, load-management reductions and any time the controller may pause. A chargepoint’s nameplate is not the guaranteed sustained vehicle power; the onboard charger, cable, supply phase and site limit may be lower.

Tariff information can go stale

Supplier-managed charging requires the correct account, vehicle, chargepoint, time zone and tariff. A tariff name does not guarantee that its hours or eligibility are unchanged.

The supplier’s current terms and the schedule shown in the app define the charge windows. Where the controller selects dynamic periods, the actual session times replace any assumption of a fixed nightly block.

Load management still has priority

A schedule permits charging; it does not reserve electrical capacity. Dynamic load balancing can reduce current when the home uses more power, even within the chosen window.

Where several chargepoints share capacity, the site controller may divide or sequence their demand. The departure target should use the realistically available power, not the sum of every nameplate rating.

If the car repeatedly misses its target, check whether the issue is insufficient window length, site throttling, a vehicle limit or loss of smart control before increasing an electrical setting.

Communications and fallback

Wi-Fi, mobile data, cloud services and vehicle APIs can fail independently. The handover should explain what the chargepoint does when each connection is lost:

continue immediately at a safe local limit
follow a stored local schedule
wait for manual authorisation
provide another documented fallback

Covered smart chargepoints must retain a means of charging when communications are unavailable, but a supplier-specific cheap-rate or optimisation service may not operate.

Keep a tested manual charging route for urgent use. Do not bypass circuit protection or installer load limits to obtain it.

Solar and home-battery interaction

A solar schedule can conflict with a tariff schedule. The chargepoint may wait for daytime surplus while the vehicle expects a night window, or a home battery may discharge into the EV when the owner intended solar-only charging.

Define priorities for:

minimum vehicle energy by departure
true solar-surplus charging
home-battery reserve
low-price grid energy
site import and export limits

Monitor the grid meter after changing modes. Similar green icons in separate apps do not prove the systems share the same definition of surplus.

A reliable setup checklist

Confirm the car is plugged in and has no conflicting timer.
Set the correct departure time, energy or state-of-charge target.
Confirm chargepoint clock, location and time zone.
Check the active tariff or control service.
Confirm the circuit and dynamic-load limits.
Allow for randomised start and reduced power.
Test communications-loss fallback.
Verify one full session in interval data.

After a vehicle, tariff, router or app change, repeat the checks. Smart charging is a control service as well as an electrical installation.