Record-Breaking Power Use Tests Portugal's Grid Amid Heatwaves

Portugal’s electricity network has just lived through its busiest nine-month stretch in a decade and a half, a surge that caught many households off-guard during the summer heat and is already shaping the country’s next moves on prices, climate targets and grid investments. The headline numbers are eye-catching—39.2 TWh consumed between January and September, the highest since 2010—yet the real story is how unusual weather, expanding industry and the silent march of electric vehicles converged, forcing renewable dams and wind farms to work overtime while gas-fired plants and cross-border imports plugged the remaining gaps.

Why the lights burned brighter than ever

Even seasoned grid planners at REN admit they did not expect demand to climb above the 2010 record this early in the decade. Analysts point first to an economy growing near 2 %, but the more immediate culprit is an exceptionally warm summer that drove air-conditioning use to unprecedented levels. Portugal logged multiple days above 40 °C, and on 5 August the system hit a demand peak of 7 891 MW, a figure usually reserved for winter cold spells. Parallel to the heat, factories ramped up production, buoyed by export orders, while electric-car charging sessions soared above 7 M in the public network, according to ERSE. Put together, these threads stitched a 2.6 % year-on-year jump in consumption, or 2 % once temperature and working-day effects are stripped out.

Heatwave economics: what the numbers tell us

Monthly data underline how strongly temperature swings now dictate power demand. June delivered a 4.4 % rise in consumption, well above the historical average, while September’s heat kept air-conditioners humming and pushed usage up another 2.2 %. REN’s meteorological models attribute roughly two-thirds of the 2025 increase to cooling needs, a pattern that matches International Energy Agency warnings that Southern Europe’s electricity grids must brace for climate-driven peaks. Crucially for Portugal, whose housing stock is still poorly insulated, the jump in cooling mirrors a similar winter spike in electric heating seen in the north of the country. The twin pressures are convincing policy-makers that energy-efficiency retrofits are as urgent as adding new power plants.

Renewables carry the bulk of the load

Despite the consumption record, the system stayed largely green. From January through September, renewables supplied 70 % of all electricity. Hydropower led the pack at 28 %, followed by wind (24 %) and a fast-growing solar fleet (13 %). Solar’s share may sound modest, yet it expanded 25 % year-on-year, underlining investor appetite after auctions pushed tariffs below €30/MWh. Biomass rounded out the mix with 5 %, highlighting how diversified Portugal’s carbon-free portfolio has become. These numbers matter politically: Lisbon promised Brussels it would hit 80 % renewable generation by 2026, a target originally slated for 2030, and the 2025 performance shows that goal is within touching distance—provided drought does not hamper river flows next year.

The back-up squad: gas turbines and Spanish electrons

Keeping the lights on during sultry evenings still required help. Gas-fired power stations covered 14 % of demand over the nine months, but their importance ballooned whenever wind dropped. September offers a case study: renewables fell to 57 % of consumption, forcing gas plants to run flat-out and pushing gas burn in the electricity sector up 132 % compared with 2024. Imports from Spain filled another gap, averaging 16 % of demand through September and spiking above a quarter in particularly still weeks. Although coal has vanished from mainland generation, the reliance on gas and imports underscores why battery storage and green hydrogen projects are being fast-tracked. Grid operator REN has already requested new cross-border capacity and 2 GW of large-scale batteries before 2030 to smooth the peaks.

What record demand means for your 2026 bill

Consumers naturally worry that higher usage will translate into fatter bills. ERSE’s latest tariff outlook is cautiously optimistic: it foresees only a 0.1 % average annual rise in household electricity prices between 2025 and 2030. The figure could have been steeper, but regulators assume that spreading €1.6 B of network investment over a larger volume of kilowatt-hours keeps the per-unit cost down. Roughly 8 % of that investment is earmarked for managing new peaks, including smarter transformers and stronger rural lines. Still, analysts warn that if 2026 experiences another extreme summer and industry acceleration, the regulator may need to revisit the numbers. For now, the main driver of any extra euro on the bill is grid modernisation, not wholesale energy prices.

The road ahead: storage, flexibility and resilience

Portugal’s response is already visible in new policy drafts. The Environment Ministry will unveil a National Energy Storage Strategy by mid-2026, pushing developers to pair wind and solar farms with batteries. In parallel, the updated National Energy and Climate Plan aims for 51 % renewables in final energy consumption, a target that extends electrification far beyond power generation into transport and heating. Experts say this broader electrification could add another 10 TWh of annual demand before 2030, making this year’s record look tame. To stay ahead, REN is studying dynamic tariffs that reward off-peak charging, while local councils eye district-level microgrids as insurance against extreme weather. The takeaway for Portuguese residents is clear: the grid is entering a new era where climate resilience and digital flexibility will matter as much as raw megawatts.