Portugal 2027 Electricity Tariff Hours Explained: Peak, Off-Peak and Super Off-Peak at a Glance
Summary
Four tariff periods. Ponta (peak), cheias (standard), vazio normal (off-peak) and super vazio (super off-peak). ERSE ranks them by how much they load the grid, and prices follow.
Three cycles. Daily (the same every day), weekly (workdays, Saturday, Sunday) and seasonal weekly (medium, high and very-high voltage only).
What changed. The peak shifts to the end of the day. The number of hours in each period stays the same; only their position changes.
Who is affected. About 500,000 households on bi- or tri-hourly tariffs and about 70,000 businesses on tetra-hourly tariffs. About 6 million simple-tariff households keep the same tariff (ERSE, 31 July 2026).
When. 1 April 2027 for BTE, MT, AT and MAT; 1 July to 31 December 2027 for BTN bi- and tri-hourly, meter by meter.
One constant. Super vazio always runs from 02:30 to 06:30.
How the Portugal 2027 electricity regulated tariff is built
Every electricity bill in mainland Portugal contains a regulated part, set by ERSE and paid whichever retailer you choose. This is the grid-access tariff (TAR), which covers global system use, transmission and distribution. Customers on regulated supply also pay regulated energy and commercialisation components. Which hours count as peak or off-peak is decided by regulation, and it is the part that changes in 2027.
What you can choose depends on your voltage level. Low-voltage normal (BTN) means contracted power up to 41.4 kVA. Low-voltage special (BTE) is above that. Medium, high and very-high voltage (MT, AT, MAT) cover the largest sites.
Segment | Tariff options | Billed variables | Cycles available |
BTN | Simple (1 price), bi-hourly (2), tri-hourly (3) | Contracted power by band; active energy | Daily or weekly |
BTE | Tetra-hourly (4 prices) | Contracted power; peak-hour power; active energy by period; reactive energy | Daily or weekly |
MT, AT, MAT | Tetra-hourly (4 prices) | Same as BTE | Weekly or seasonal weekly |
Two details matter for cost. First, peak-hour power (potência em horas de ponta) is the average power taken during the peak hours, and it is billed to BTE, MT, AT and MAT but not to BTN. Moving the peak therefore moves a power charge as well as an energy price. Second, contracted power for these segments follows the highest 15-minute average power of the last 12 months. In the free market, the grid-access charges follow the regulated hours, while the energy price hours are set by your contract, which retailers typically align with them.
Three cycles, and who gets which
A cycle is the rule that says how the day and the week are cut into periods. There are three.
Daily cycle. The same periods every day of the year: no weekends, no holidays, and from 2027 no summer/winter difference. Available to BTN and BTE.
Weekly cycle. Different periods for workdays (with a winter and a summer version), Saturdays and Sundays. Available at every voltage level. The old optional weekly cycle for MT, AT and MAT is discontinued and merged into it.
Seasonal weekly cycle. Workday and weekend tables that also change by month (high, medium and low season) and by grid area A, B or C. Available only to MT, AT and MAT, who may also use the plain weekly cycle.
Segment | Daily | Weekly | Seasonal weekly |
BTN (bi- and tri-hourly) | Yes | Yes | No |
BTE | Yes | Yes | No |
MT, AT, MAT | No | Yes | Yes |
BTN customers on the simple tariff pay one price all day, so no cycle changes their bill. Their meters are still updated between 1 November 2027 and 31 March 2030 so that hourly readings use the new periods.
The 2027 tariff clock: every cycle in one picture
The picture below shows the new daily and weekly cycles on one page. Tetra-hourly customers (BTE, MT, AT, MAT) are billed on all four colours; BTN bi- and tri-hourly customers use the same clock with merged prices, explained further down. Red is the expensive peak, dark green the cheapest super off-peak. Read each row left to right as a 24-hour day.
Three things stand out. The peak now sits at the end of the day in every row that has one. In the weekly cycle the weekend has no peak at all, while the daily cycle bills the same peak seven days a week. And the super off-peak never moves: 02:30 to 06:30 in every row.
Cycle and day | Peak (ponta) | Standard (cheias) | Off-peak (vazio normal) | Super off-peak |
Daily, every day | 17:30–21:30 | 08:30–17:30, 21:30–22:30 | 00:00–02:30, 06:30–08:30, 22:30–24:00 | 02:30–06:30 |
Weekly, workday, winter time | 17:00–22:00 | 00:00–00:30, 07:30–17:00, 22:00–24:00 | 00:30–02:30, 06:30–07:30 | 02:30–06:30 |
Weekly, workday, summer time | 19:30–22:30 | 00:00–00:30, 07:30–19:30, 22:30–24:00 | 00:30–02:30, 06:30–07:30 | 02:30–06:30 |
Weekly, Saturday | none | 17:00–24:00 | 00:00–02:30, 06:30–17:00 | 02:30–06:30 |
Weekly, Sunday | none | none | 00:00–02:30, 06:30–24:00 | 02:30–06:30 |
Times are Portugal mainland legal time; each interval starts at its first time and ends just before its last. Durations do not change from today: the daily cycle has 4 peak hours, and the weekly workday has 5 peak hours in winter and 3 in summer.
A detail that surprises people. On weekdays the weekly off-peak now starts at 00:30, not 00:00, so the first half hour of every workday is standard. ERSE states the shift for the bi-hourly option: off-peak starts at 00:30 instead of 00:00 on workdays, and at 22:30 instead of 22:00 in the daily cycle (ERSE, 31 July 2026).
Four prices, three prices, two prices
Tetra-hourly customers (all BTE, MT, AT, MAT) are billed on all four periods. BTN tri-hourly customers see three prices: super off-peak and off-peak merge into one "vazio". BTN bi-hourly customers see two: peak and standard merge into "fora de vazio". The next picture shows one winter workday billed all three ways.
The seasonal weekly cycle (MT, AT, MAT): months and grid areas
Large customers on the seasonal weekly cycle get a calendar on top of the clock. Each month is high (alta), medium (média) or low (baixa) season, and the calendar depends on the grid area of the installation. ERSE defines three areas that broadly correspond to the north (A), centre (B) and south (C) of the mainland, and the maps for areas A and B are identical (ERSE). The south peaks in summer, the north and centre in winter.
Within each season the peak window on a workday is different, and it is always in the late afternoon or evening.
Workday peak window | High season | Medium season | Low season |
Areas A and B | 17:00–22:00 | 17:30–22:30 | 19:00–22:00 |
Area C | 18:30–23:30 | 17:00–22:00 | 18:00–21:00 |
In every season, super off-peak is 02:30–06:30, off-peak is 00:30–02:30 and 06:30–07:30, and the rest of the workday is standard outside the peak. The peak is 5 hours in high and medium season and 3 hours in low season.
Saturdays, Sundays and national holidays have no peak. They have one 3-hour standard (cheias) window in the evening, and everything else is off-peak or super off-peak:
Weekend and holiday standard window | High season | Medium season | Low season |
Areas A and B | 18:30–21:30 | 19:00–22:00 | 19:30–22:30 |
Area C | 19:30–22:30 | 18:30–21:30 | 18:00–21:00 |
Check your area. The area is a property of each installation (CPE), not of the company. Multi-site portfolios in the north and the south can sit in different areas and so peak at different hours in the same month.
Summer time, winter time and holidays: the rules that trip up data
Summer and winter. Tariff hours follow legal time. Winter time runs from the last Sunday of October to the last Sunday of March (ERSE). In 2027 summer time starts on 28 March and ends on 31 October. The summer/winter split only matters for the weekly cycle on workdays; the daily cycle is now identical all year, and the seasonal cycle follows months instead. The clock changes always fall on a Sunday, which uses the same table in both seasons, so the changeover day is unambiguous, but it has 92 or 100 quarter-hours instead of 96, which breaks naive data pipelines.
Holidays. The rule depends on the cycle and the voltage level.
Cycle and segment | A national holiday is billed as | Basis |
Daily (BTN, BTE) | An ordinary day: the cycle has no day types | Cycle definition |
Weekly, BTN and BTE | No special rule: the holiday keeps its weekday's table | ERSE consultation justification; confirm with your retailer |
Weekly, MT, AT, MAT | A Sunday | Directive n.º 3/2026 |
Seasonal weekly, MT, AT, MAT | A weekend day (Saturday/Sunday table) | Directive n.º 3/2026 |
The 13 national statutory holidays in 2027 are 1 January, 26 March (Good Friday), 28 March (Easter Sunday), 25 April, 1 May, 27 May (Corpus Christi), 10 June, 15 August, 5 October, 1 November, 1 December, 8 December and 25 December. Carnival and municipal holidays are not national holidays. Five of them fall on a weekend in 2027 (28 March, 25 April, 1 May, 15 August, 25 December), so only eight create a real change on a workday. For 1 May and 25 December, which fall on Saturdays, the Directive's wording points to the Sunday table for MT, AT and MAT on the weekly cycle; we recommend confirming this reading with E-REDES before you build billing checks on it.
Why it matters. A 15-minute reading is billed at the price of the period it falls in. A single wrong holiday, a one-hour clock error or a start-versus-end timestamp mix-up silently moves energy between peak and standard across a whole year of data.
When it changes, and how to get ready
Business customers (BTE, MT, AT, MAT) change on a single date, 1 April 2027, and the update is automatic. Households and small businesses on bi- or tri-hourly BTN change meter by meter between 1 July and 31 December 2027. Simple-tariff meters are updated between 1 November 2027 and 31 March 2030, but their tariff does not change (ERSE). Nothing needs to be signed for the new hours to apply, which is exactly why an unprepared portfolio is the one that gets surprised.
A readiness check for each installation takes five steps:
Identify the facts per CPE: voltage level, tariff option, cycle, grid area and effective date.
Collect the data: at least 12 months of invoices and of E-REDES 15-minute readings.
Re-classify every reading under the new periods, with the right clock, season and holiday rules.
Compare energy by period and, for BTE, MT, AT and MAT, peak-hour power, before and after.
Decide: shift or shed flexible loads, add storage, or change cycle or contract where the rules allow it.
The prize for step 5 is concrete. A building whose load sits in the new evening window pays more even though it consumes the same energy, and a building that already consume mostly in the middle of the day can pay less. See a real example, a client with solar PV and no battery.
Quick answers
What are the new peak hours in Portugal 2027 electricity tariff? In the daily cycle 17:30–21:30. In the weekly cycle on workdays 17:00–22:00 in winter time and 19:30–22:30 in summer time. Seasonal weekly windows are in the table above.
When do they start? 1 April 2027 for BTE, MT, AT and MAT; between 1 July and 31 December 2027 for BTN bi- and tri-hourly.
Does the simple tariff change? No. Simple-tariff customers keep one price all day, and only their meter readings are updated to the new periods.
Does the number of peak hours change? No. Durations stay the same; only the position moves.
Do holidays count as weekends? For MT, AT and MAT on the weekly cycle, yes: holidays use the Sunday table. For BTN and BTE on the weekly cycle there is no holiday rule, and the daily cycle ignores holidays.
Why Builtrix is the right partner to optimize your electricity tariff in Portugal?
Tariff hours look simple on a poster and are unforgiving in a spreadsheet. Three cycles with five day types, two clock seasons, three grid areas, legal-time changes of 92 and 100 quarter-hours, and a different effective date for every CPE: this is the detail that decides whether a savings figure is right. Builtrix asset intelligence platform works with exactly the data that settles it, your invoices and E-REDES 15-minute readings, and applies the official tariff calendar to each installation. That means we can show, asset by asset and CPE by CPE, how many kWh and how much peak-hour power move into or out of each period when the new hours apply, and then which actions reduce the cost.
Our clients already receive insights on how to limit the impact of the new timing in their buildings. If you manage a portfolio, the most useful step now is to see it under the 2027 periods before April 2027.
Sources
ERSE, Diretiva n.º 3/2026 (new hourly periods) and Declaração de Retificação n.º 889/2026/2
ERSE, 10 questions and answers on the new periods and consultation CP137 explainer
ERSE, Tariff structure of the electricity sector 2025 and Regulamento Tarifário (Regulamento n.º 1218/2025)
