Glossary

Electricity market glossary

Every term used in the Portuguese electricity market, defined plainly. Cross-referenced with our comparator and methodology.

kWh (Kilowatt-hour): Unit of energy consumed. 1 kWh equals running a 1000 W appliance for one hour. It is the base unit for electricity billing — multiplied by the tariff’s per-kWh price it gives the energy component of the bill.
kVA (Kilovolt-ampere): Unit of electrical power. Defines the maximum contracted load — how much your installation can draw simultaneously. Common residential tiers in Portugal are 3.45, 4.6, 6.9, 10.35 and 13.8 kVA. The higher the tier, the higher the daily standing charge, regardless of consumption.
TAR (Network Access Tariff): Regulated rate set by ERSE that pays for electricity transport and distribution. Identical across all retailers and present on every bill, with two components: TAR-energy (€/kWh) and TAR-power (€/day × kVA). On dual- and triple-rate tariffs, TAR-energy varies by period (off-peak, peak, etc.).
IEC (Excise Tax on Electricity Consumption): Excise tax charged per kWh consumed, set by the Portuguese State. Appears on every bill, identical across all retailers. The 2026 rate is €0.001/kWh.
DGEG (General Directorate of Energy and Geology): Portuguese government body regulating and supervising the energy sector. The DGEG levy is a monthly regulatory fee on every bill — small (~€0.07/month in 2026) and identical across retailers.
Audiovisual Contribution: Fixed monthly charge on the electricity bill that funds the Portuguese public broadcaster (RTP). The 2026 rate is €2.85/month for non-exempt residential customers. Identical across retailers.
VAT (Value Added Tax): VAT applies in two brackets on electricity bills: 6% on energy and power up to 100 kWh per 30 days (200 kWh for households with 4+ dependants); 23% on the excess, on regulated charges (TAR, IEC, DGEG, audiovisual) and on the subscription portion. Every price we display already includes VAT.
ERSE (Energy Services Regulator): Independent regulator of the Portuguese energy sector. Sets regulated tariffs (TAR), approves the last-resort retailer’s prices and supervises the liberalised market. Publishes the Electricity Price Simulator — the primary data source for our comparator.
MIBEL (Iberian Electricity Market): Wholesale market integrating Portugal and Spain since 2007. MIBEL spot prices set the reference for indexed tariffs — when MIBEL falls, indexed offers become more competitive; when it rises, fixed tariffs protect the consumer.
OMIE (Iberian Energy Market Operator): Iberian electricity exchange that publishes daily hourly MIBEL spot prices. Indexed-tariff contracts use these prices as their reference. Each OMIE hourly slot feeds the final price paid by indexed consumers.
Liberalised market: Segment of the electricity market where private retailers compete freely. More than 24 active retailers in Portugal in 2026. Switching between retailers is free and does not interrupt supply — the physical grid (E-REDES) stays the same.
Regulated market / SU Eletricidade: Last-resort retailer (CUR), operated by EDP Serviço Universal, with quarterly rates fixed by ERSE. Serves as a reference but is frequently more expensive than the best liberalised-market offers. Progressively closed to new domestic consumers since 2013.
Retailer: Company that sells electricity to the end consumer in the liberalised market. Buys electricity wholesale (MIBEL) and resells with its commercial margin. In Portugal: EDP Comercial, Galp, Endesa, Iberdrola, Goldenergy, Repsol, Coopérnico, among others. Not to be confused with the distributor (E-REDES), which manages the physical grid.
E-REDES (Distributor): Distribution grid operator in mainland Portugal. Manages physical transport down to the consumer’s home — independent of which retailer the customer chooses. E-REDES is paid via TAR and exposes the public Diagrama de Carga API with 15-minute consumption curves.
CPE (Delivery Point Code): Unique identifier of the electricity installation, formatted PT0002... followed by 18 characters. Found on any bill or on the fusebox. Required for any retailer switch and for signing up to a new tariff.
Flat-rate tariff: Time-of-use mode in which the energy price is identical throughout the day, every day. Easier to forecast. Recommended if consumption is uniform or if there is little flexibility to shift usage to off-peak hours.
Dual-rate tariff: Time-of-use mode with two prices: peak (more expensive, generally 8h–22h on the daily cycle, or weekdays only on the weekly cycle) and off-peak (cheaper, remaining hours and weekends). Worth it when the user can shift usage — washing machine, heating, EV charging — to the off-peak window.
Triple-rate tariff: Time-of-use mode with three prices: peak (highest price, demand peaks), mid-peak (intermediate) and off-peak (lowest, night and weekends). Higher savings potential but more complexity. ERSE does not publish residential triple-rate prices in the simulator — we collect that data directly from retailers when available.
Daily cycle: Time-of-use schedule in dual-rate tariffs where the off-peak window is fixed every day (typically 22h–8h or 23h–9h). Recommended when the user is out during the day and consumes mostly at night.
Weekly cycle: Time-of-use schedule in dual-rate tariffs where the off-peak window covers entire weekends plus weeknight hours. Recommended for users at home during weekend days — shifts heavy loads (washer/dryer) to Saturday/Sunday.
Lock-in / Fidelidade: Contractual commitment to stay with a retailer for a period (typically 12 or 24 months), with an early-exit penalty. The penalty is usually proportional to remaining months. We always surface a fidelity_lock flag in the UI with the exact penalty.
Promotional discount: Percentage or fixed reduction over the base price, applied for a limited period (often 6, 12 or 24 months). After the promo ends, the price reverts to base — which is why we rank by steady-state cost, not year-1 cost. See the methodology for details.
Indexed tariff: Tariff whose energy price tracks the wholesale market (MIBEL/OMIE) hour-by-hour, plus a commercial margin and TAR. Daily variance can be high — favourable in low-price periods, exposed in stress periods (summer 2022 saw OMIE above €200/MWh). We always surface the indexed_volatile flag.
Direct debit: Automatic bill payment via SEPA bank mandate. Many competitive tariffs require it as a sign-up condition. We surface the requires_direct_debit flag.
E-bill: Bill delivery by email instead of paper. Often required for cheaper offers. We surface the requires_ebill flag.
NIF (Tax identification number): Portuguese tax identification number, required for any electricity supply contract. Obtained at any Finanças office or via Portal das Finanças. For non-EU residents, a tax representative is required.
SEPA IBAN: International bank account identifier in the SEPA area (EU + a few others). Portuguese IBANs (PT50...) are accepted by every retailer; non-Portuguese IBANs are accepted only by some — Iberdrola and Endesa are the most permissive.
Large household: Household with 4 or more dependants. Eligible for the reduced 6% VAT band up to 200 kWh/30 days instead of the standard 100 kWh/30 days. The reduction must be declared to the retailer to be applied.
Green mix / 100% renewable energy: Tariff where the retailer guarantees that all electricity sold to the consumer is certified as renewable (hydro, wind, solar, biomass). Certification is via Guarantees of Origin issued by DGEG. It does not mean the electron you receive is renewable — it means the retailer bought matching guarantees.
CUR (Last-resort retailer): State-appointed retailer that supplies electricity to consumers who did not choose any retailer in the liberalised market. In mainland Portugal this is SU Eletricidade (EDP group). Rates set quarterly by ERSE — typically more expensive than the best free-market offers.

Glossary

Electricity market glossary

Every term used in the Portuguese electricity market, defined plainly. Cross-referenced with our comparator and methodology.

kWh (Kilowatt-hour): Unit of energy consumed. 1 kWh equals running a 1000 W appliance for one hour. It is the base unit for electricity billing — multiplied by the tariff’s per-kWh price it gives the energy component of the bill.
kVA (Kilovolt-ampere): Unit of electrical power. Defines the maximum contracted load — how much your installation can draw simultaneously. Common residential tiers in Portugal are 3.45, 4.6, 6.9, 10.35 and 13.8 kVA. The higher the tier, the higher the daily standing charge, regardless of consumption.
TAR (Network Access Tariff): Regulated rate set by ERSE that pays for electricity transport and distribution. Identical across all retailers and present on every bill, with two components: TAR-energy (€/kWh) and TAR-power (€/day × kVA). On dual- and triple-rate tariffs, TAR-energy varies by period (off-peak, peak, etc.).
IEC (Excise Tax on Electricity Consumption): Excise tax charged per kWh consumed, set by the Portuguese State. Appears on every bill, identical across all retailers. The 2026 rate is €0.001/kWh.
DGEG (General Directorate of Energy and Geology): Portuguese government body regulating and supervising the energy sector. The DGEG levy is a monthly regulatory fee on every bill — small (~€0.07/month in 2026) and identical across retailers.
Audiovisual Contribution: Fixed monthly charge on the electricity bill that funds the Portuguese public broadcaster (RTP). The 2026 rate is €2.85/month for non-exempt residential customers. Identical across retailers.
VAT (Value Added Tax): VAT applies in two brackets on electricity bills: 6% on energy and power up to 100 kWh per 30 days (200 kWh for households with 4+ dependants); 23% on the excess, on regulated charges (TAR, IEC, DGEG, audiovisual) and on the subscription portion. Every price we display already includes VAT.
ERSE (Energy Services Regulator): Independent regulator of the Portuguese energy sector. Sets regulated tariffs (TAR), approves the last-resort retailer’s prices and supervises the liberalised market. Publishes the Electricity Price Simulator — the primary data source for our comparator.
MIBEL (Iberian Electricity Market): Wholesale market integrating Portugal and Spain since 2007. MIBEL spot prices set the reference for indexed tariffs — when MIBEL falls, indexed offers become more competitive; when it rises, fixed tariffs protect the consumer.
OMIE (Iberian Energy Market Operator): Iberian electricity exchange that publishes daily hourly MIBEL spot prices. Indexed-tariff contracts use these prices as their reference. Each OMIE hourly slot feeds the final price paid by indexed consumers.
Liberalised market: Segment of the electricity market where private retailers compete freely. More than 24 active retailers in Portugal in 2026. Switching between retailers is free and does not interrupt supply — the physical grid (E-REDES) stays the same.
Regulated market / SU Eletricidade: Last-resort retailer (CUR), operated by EDP Serviço Universal, with quarterly rates fixed by ERSE. Serves as a reference but is frequently more expensive than the best liberalised-market offers. Progressively closed to new domestic consumers since 2013.
Retailer: Company that sells electricity to the end consumer in the liberalised market. Buys electricity wholesale (MIBEL) and resells with its commercial margin. In Portugal: EDP Comercial, Galp, Endesa, Iberdrola, Goldenergy, Repsol, Coopérnico, among others. Not to be confused with the distributor (E-REDES), which manages the physical grid.
E-REDES (Distributor): Distribution grid operator in mainland Portugal. Manages physical transport down to the consumer’s home — independent of which retailer the customer chooses. E-REDES is paid via TAR and exposes the public Diagrama de Carga API with 15-minute consumption curves.
CPE (Delivery Point Code): Unique identifier of the electricity installation, formatted PT0002... followed by 18 characters. Found on any bill or on the fusebox. Required for any retailer switch and for signing up to a new tariff.
Flat-rate tariff: Time-of-use mode in which the energy price is identical throughout the day, every day. Easier to forecast. Recommended if consumption is uniform or if there is little flexibility to shift usage to off-peak hours.
Dual-rate tariff: Time-of-use mode with two prices: peak (more expensive, generally 8h–22h on the daily cycle, or weekdays only on the weekly cycle) and off-peak (cheaper, remaining hours and weekends). Worth it when the user can shift usage — washing machine, heating, EV charging — to the off-peak window.
Triple-rate tariff: Time-of-use mode with three prices: peak (highest price, demand peaks), mid-peak (intermediate) and off-peak (lowest, night and weekends). Higher savings potential but more complexity. ERSE does not publish residential triple-rate prices in the simulator — we collect that data directly from retailers when available.
Daily cycle: Time-of-use schedule in dual-rate tariffs where the off-peak window is fixed every day (typically 22h–8h or 23h–9h). Recommended when the user is out during the day and consumes mostly at night.
Weekly cycle: Time-of-use schedule in dual-rate tariffs where the off-peak window covers entire weekends plus weeknight hours. Recommended for users at home during weekend days — shifts heavy loads (washer/dryer) to Saturday/Sunday.
Lock-in / Fidelidade: Contractual commitment to stay with a retailer for a period (typically 12 or 24 months), with an early-exit penalty. The penalty is usually proportional to remaining months. We always surface a fidelity_lock flag in the UI with the exact penalty.
Promotional discount: Percentage or fixed reduction over the base price, applied for a limited period (often 6, 12 or 24 months). After the promo ends, the price reverts to base — which is why we rank by steady-state cost, not year-1 cost. See the methodology for details.
Indexed tariff: Tariff whose energy price tracks the wholesale market (MIBEL/OMIE) hour-by-hour, plus a commercial margin and TAR. Daily variance can be high — favourable in low-price periods, exposed in stress periods (summer 2022 saw OMIE above €200/MWh). We always surface the indexed_volatile flag.
Direct debit: Automatic bill payment via SEPA bank mandate. Many competitive tariffs require it as a sign-up condition. We surface the requires_direct_debit flag.
E-bill: Bill delivery by email instead of paper. Often required for cheaper offers. We surface the requires_ebill flag.
NIF (Tax identification number): Portuguese tax identification number, required for any electricity supply contract. Obtained at any Finanças office or via Portal das Finanças. For non-EU residents, a tax representative is required.
SEPA IBAN: International bank account identifier in the SEPA area (EU + a few others). Portuguese IBANs (PT50...) are accepted by every retailer; non-Portuguese IBANs are accepted only by some — Iberdrola and Endesa are the most permissive.
Large household: Household with 4 or more dependants. Eligible for the reduced 6% VAT band up to 200 kWh/30 days instead of the standard 100 kWh/30 days. The reduction must be declared to the retailer to be applied.
Green mix / 100% renewable energy: Tariff where the retailer guarantees that all electricity sold to the consumer is certified as renewable (hydro, wind, solar, biomass). Certification is via Guarantees of Origin issued by DGEG. It does not mean the electron you receive is renewable — it means the retailer bought matching guarantees.
CUR (Last-resort retailer): State-appointed retailer that supplies electricity to consumers who did not choose any retailer in the liberalised market. In mainland Portugal this is SU Eletricidade (EDP group). Rates set quarterly by ERSE — typically more expensive than the best free-market offers.