How to find the break-even point for a time-of-use plan

Use your real time split

A time-of-use comparison needs kWh by period, not only the total. Smart-meter portals, interval-data downloads or a representative bill can provide the split. If you do not have it, test several labelled scenarios rather than claiming one answer.

Calculate each plan independently

Multiply peak kWh by the peak rate and off-peak kWh by the off-peak rate. Add any difference in fixed charges. Then price the same total kWh under the flat plan. The lower result is valid only for that usage pattern and tariff period.

Interpret break-even carefully

The break-even off-peak share is the proportion of total use that makes both entered plans equal. A household needs a larger off-peak share when the peak penalty is high or when the time-of-use plan has a higher fixed charge.

• Check weekends and public holidays.
• Check seasonal rates and controlled loads.
• Check whether EV charging or heating can actually move.

Re-test after behaviour changes

Moving an EV charge or water-heating cycle can change the split. Save both the before and after scenarios, but do not assume every appliance can be shifted safely or conveniently.