Portugal's energy regulator, ERSE, announced final approval of new time-of-use periods for electricity tariffs in mainland Portugal on July 31, closing a public consultation process launched in November 2025 that drew 31 submissions from consumers, retailers, and industry groups. The final version differs from the proposal released for consultation, with several details revised after feedback.
The change affects roughly 500,000 residential customers on bi-hourly (386,000) or tri-hourly (112,000) tariffs, plus about 70,000 business and industrial customers on tetra-hourly tariffs. The vast majority of Portugal's roughly six million residential customers, those on a flat-rate tariff, aren't affected in price, ERSE says, though their smart meters will still be updated so they can see what they'd have paid under a time-based plan.
Why ERSE is doing this
ERSE says the goal is to align pricing periods with how the grid is actually used now, not how it was used when the current periods were set. Two things have changed significantly: decentralized renewable generation has grown a lot, and by the end of the first half of 2025, 99% of residential electricity customers had a smart meter installed, making time-based pricing far more practical to implement and monitor than before. Charging more during high-demand hours and less during low-demand hours is meant to push some consumption toward off-peak periods, which ERSE says can reduce how much money needs to be spent reinforcing the grid, a cost that otherwise gets passed on to everyone.
What actually changes
For bi-hourly tariffs, the off-peak ("vazio") period simply starts and ends half an hour later. In the daily cycle, it now begins at 10:30pm instead of 10:00pm, and the peak-priced period now begins at 8:30am instead of 8:00am. In the weekly cycle, weekday off-peak hours now start at 12:30am. Saturdays get simplified too: instead of two separate peak-priced windows, morning and evening, there's now a single seven-hour peak block from 5pm to midnight, with the rest of Saturday and all of Sunday counted as off-peak.
For tri-hourly tariffs, the bigger change is that peak ("ponta") hours move to the end of the day, and the morning peak period disappears entirely. The daily cycle no longer differs between winter and summer clock changes, one set of hours applies year-round. In that daily cycle, the peak period now ends at 9:30pm, rather than 8:30pm in winter or 9:00pm in summer. In the weekly cycle, winter peak hours now end at 10:00pm rather than 9:00pm, and summer peak hours shift to the end of the afternoon, ending at 10:30pm.
Tetra-hourly tariffs, mandatory for non-residential customers, follow the same logic, peak hours consolidated at the end of the day, with morning and early-afternoon peak periods eliminated. These customers move to a single weekly cycle, though a seasonal alternative remains available for 60 days after the change takes effect, splitting the year into three pricing seasons and the country into three network zones. Across all tariff types, the total number of hours in each pricing period stays the same, only the start and end times move.
Does this actually change your price?
Not directly. The price per kilowatt-hour isn't changing because of this decision. What changes is when your retailer considers your electricity use to be off-peak, mid-peak, or peak. Whether your bill goes up or down depends entirely on when you actually use electricity relative to the new hours, not on any new rate being introduced.
Does this save you money?
Not automatically, and not for everyone. ERSE itself acknowledges the impact could be positive or negative depending on your household's actual consumption pattern, and how much of it you're able to shift toward the new cheaper hours. The regulator says it will provide tools letting individual customers simulate the impact on their own bill, without committing to a specific timeline for when those tools will be available.
The practical version: if you run your washing machine, dishwasher, water heater, or electric vehicle charger on a timer set for the old off-peak hours, that timer needs to move by roughly 30 minutes to keep hitting the cheap window. Electricity retailers are required to reflect the new periods in their offers, though they can negotiate different hours specifically for the energy portion of your bill with individual customers if both sides agree. Existing contracts don't automatically become invalid, retailers will update the applicable time periods when the new schedule takes effect, and customers remain free to switch tariff types if a different option suits their usage better.
Another practical change
Switching between tariff types, simple, bi-hourly, or tri-hourly, no longer requires waiting a set period between changes, under an amendment to the Tariff Regulation approved in October 2025. Switching cycles is a different matter: that still requires staying on your current cycle for at least 12 months first.
When this actually happens
Nothing changes immediately. For residential customers and small businesses on bi-hourly or tri-hourly tariffs, the new periods roll out between July 1 and December 31, 2027, in phases rather than all at once. Most of the switch happens remotely through smart meters, with only a small number of customers needing an in-person technical visit. Non-residential tetra-hourly customers move over starting April 1, 2027. Flat-rate customers, who aren't affected by any of this pricing-wise, will still get their meters updated to show time-of-use data between November 2027 and March 2030, or sooner if they request it directly from E-Redes, the grid operator.