When do the dual-rate hours change?

Between 1 July and 31 December 2027. The grid operator switches your meter remotely, on a date that varies by home. You do not need to do anything.

Is dual rate still worth it after the change?

Off-peak still lasts 10 hours a day; it just starts half an hour later. If you have appliances set to start at 22:00, move them to 22:30 and you avoid paying more.

I am on the flat rate. Does this affect me?

No. The change only moves the dual-rate and triple-rate hours. Between November 2027 and March 2030 your meter will also start showing usage per period, so you can check whether dual rate pays off.

New ERSE time periods

Dual-rate calculator 2027

In 2027 off-peak starts half an hour later. Enter your usage and see whether dual rate (bi-horário) still beats the flat rate (simples).

What changes in 2027

Daily cycle: off-peak moves from 22:00–08:00 to 22:30–08:30.
Weekly cycle, weekdays: off-peak runs 0:30–7:30 (today 0:00–7:00).
Each period keeps the same number of hours, and the summer/winter difference ends.
Your smart meter is switched remotely between 1 July and 31 December 2027, on a different date for each home.
On the flat rate, nothing changes.

Source: ERSE press release of 31 July 2026 (Portuguese)

Indexed tariffMonthly usage (kWh)Share of usage off-peak40%On your bill: off-peak kWh divided by the total.Fixed usage 22:00–22:30 (kWh per day)E.g. a water heater or appliance set to start at 22:00. From 2027 this half hour is peak (fora de vazio).

Flat rate: 681 €/year
Dual rate today−12 € vs flat rate: 669 €/year
Dual rate from 2027−12 € vs flat rate: 669 €/year

On this tariff, dual rate never pays off.

Per year: energy, grid access charge (TAR), IEC and VAT (for contracted power up to 6.9 kVA). No power or fixed fees. The 8:00–8:30 gain (it becomes off-peak) is not counted.

Quick answers

When do the dual-rate hours change?: Between 1 July and 31 December 2027. The grid operator switches your meter remotely, on a date that varies by home. You do not need to do anything.
Is dual rate still worth it after the change?: Off-peak still lasts 10 hours a day; it just starts half an hour later. If you have appliances set to start at 22:00, move them to 22:30 and you avoid paying more.
I am on the flat rate. Does this affect me?: No. The change only moves the dual-rate and triple-rate hours. Between November 2027 and March 2030 your meter will also start showing usage per period, so you can check whether dual rate pays off.

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