The PV Paradox at 46℃: Europe's High Temperatures Increase Power Generation but Reduce Efficiency, Putting Double Pressure on the Power Grid

A heatwave swept across the European continent, with record-breaking solar power generation contrasting sharply with the simultaneous decline in PV efficiency. The power grid struggled under the dual pressures of soaring air conditioning loads and insufficient energy storage.

In 2024, Europe saw new installations of 65.5 GW, including 27.51 GW of centralized installations and 38 GW of distributed installations. Compared to the 62.8 GW in 2023, this represented a 4% increase YoY.

Meanwhile, the European continent was undergoing an unprecedented energy stress test. The latest data from the German Solar Industry Association showed that the country's cumulative PV installed capacity had reached 107.5 GW, covering diverse scenarios such as rooftops, balconies, and open-air sites, marking a significant milestone halfway towards Germany's 215 GW target by 2030.

However, amidst the record-breaking heat, these gleaming solar panels were facing the dilemma of declining efficiency.

01 Extreme Heatwave Sweeps Across Europe

Europe in the summer of 2025 had become a veritable "oven". In some parts of Spain, temperatures soared to 46°C, breaking the high-temperature record since 1965. In Moura, Portugal, temperatures reached an astonishing 46.6°C.

France experienced its hottest June on record, with temperatures reaching 40.9°C. The meteorological service issued an orange heatwave alert for 88% of the country's departments for the first time. Italy issued a red alert, the highest level, for 21 cities, with the entire European continent engulfed in the heatwave.

UN Secretary-General António Guterres warned that such extreme heat had become the "new normal". The climate crisis had escalated comprehensively, threatening not only public health but also dealing a heavy blow to agriculture, energy, the labour market, and supply chains, adding obstacles to the already fragile global economic recovery.

Under the heatwave, Europe's energy system faced severe challenges. On July 1, daily electricity demand in Germany, France, and Spain increased by 6%, 9%, and 14% respectively compared to the previous week. In France, peak electricity demand surged by 12%, in Spain by 15%, and in Germany and Poland by 5% each.

02 The Double-Edged Sword of Solar Power Generation

Solar power generation under high temperatures presented a paradoxical scenario. On the one hand, EU solar power generation reached a record high of 45.4 TWh in June, a 22% increase compared to the same period last year. During the heatwave peak in Germany, solar power generation exceeded 50 GW, accounting for 33% to 39% of the country's electricity supply.

On the other hand, high temperatures were eroding the efficiency of solar panels. Data from the German Meteorological Service showed that when temperatures in many areas exceeded 40°C in June, PV efficiency declined by 8%-12%. Meanwhile, the surge in air conditioning loads led to a 35% increase YoY in peak power grid pressure.

Nuclear and thermal power plants are more vulnerable under high temperatures. Among France's 18 nuclear power plants, 17 faced production declines during the high-temperature period. Due to excessively high river water temperatures, which could not be used to cool the reactors, nuclear power plants were forced to cut production or even temporarily shut down.

03 Dual pressures on the power grid system

The European power grid is under unprecedented dual pressures. On the one hand, the surge in cooling demand has led to a continuous rise in peak electricity consumption; on the other hand, the efficiency of traditional power generation methods has decreased under high temperatures, and the efficiency of PV power generation has also been affected.

Fluctuations in electricity prices are a direct manifestation of this pressure. On July 1, the daily average electricity price in Spain rose by 15%, in Poland by 106%, in France by 108%, and in Germany by as much as 175%. In Poland, the day-ahead electricity price spread once approached 500 euros per megawatt hour, with a significant gap between the lowest and highest prices.

The aging of power grid infrastructure has been further exacerbated under high temperatures. The power outage in Italy on July 1 is suspected to be related to cable overheating. On April 28 this year, large-scale power outages occurred in Spain, Portugal, and southern France, affecting over 50 million people.

04 The fatal weakness of insufficient energy storage

In the face of severe fluctuations in power supply, the lack of energy storage systems has become a fatal weakness in Europe's energy system. Germany's installed energy storage capacity is only 12 gigawatt hours (GWh), which can only meet 3% of the storage demand for PV power generation.

Industry forecasts indicate that to achieve the 2030 climate neutrality goal, the energy storage scale needs to expand to over 80 GWh. However, the latest draft from Germany's Federal Ministry of Economics shows that the energy storage subsidy budget has been cut by 20% compared to the original plan, raising market concerns about the pace of transformation.

The reduction of traditional generating units has led to insufficient grid rotational inertia, while wind and PV power do not have rotating "large wheels," resulting in a decline in the "inertial buffering force" of the entire power grid. This structural defect is highly prone to evolving into a systemic collapse under extreme weather conditions.

05 The warning from the April power outage

The large-scale power outage on April 28 this year has sounded the alarm for Europe's energy system. Spain and Portugal experienced sudden widespread power outages, leading to traffic paralysis, communication disruptions, and affecting over 50 million people.

Within just 5 seconds, approximately 15 GW of power generation capacity suddenly disappeared, equivalent to 60% of Spain's national electricity demand at that time. Spanish Prime Minister Pedro Sánchez acknowledged in a national address that there had been a "severe fluctuation" in the power system.

This incident exposed the stability risks of power grids with a high proportion of renewable energy. On the day of the power outage, Spain's wind power output plummeted by 85%, and PV power generation sharply decreased due to high temperatures and sand and dust coverage, while the energy storage capacity accounted for only 2% of the installed renewable energy capacity, unable to smooth out the 12.3 GW power fluctuations.

The deeper issue lies in insufficient power grid interconnection. By the end of 2024, Spain's cross-border transmission capacity reached only 7.2%, far below the EU's 15% interconnection target. This "energy island" status makes it difficult for Spain to receive support from neighboring countries during crises.

06 The Future Path of Energy Systems

Facing increasingly severe challenges, Europe is exploring multiple solutions. ESS deployment is considered key to achieving spatiotemporal transfer of electricity supply and demand. Germany possesses 14GW of battery storage projects and 10GW of pumped hydro systems, which partially bridge the gap between production and consumption peaks.

Meanwhile, vehicle-to-grid (V2G) technology is emerging as a new option for distributed regulation capabilities. This technology allows EVs to feed stored electricity back into the grid when not in use, effectively deploying small-scale ESS units at user endpoints. Germany's Energy Industry Act mandates that all government-procured light commercial vehicles must have bidirectional charging capability starting from 2024.

Regarding technological choices, concentrated solar power and compressed air ESS that can simultaneously provide physical rotational inertia and spinning reserve capacity are gaining attention. These technologies can compensate for the reduced "inertial buffer" in power grids caused by phasing out traditional thermal power.

The EU is pursuing systemic reforms. Germany and nine other countries submitted a proposal to the European Commission calling for establishing a "PV critical raw material strategic reserve" and relaxing trade restrictions on Chinese PV products. Concurrently, the German parliament is expected to review the Renewable Energy Acceleration Act, which proposes delegating PV project approval authority to state-level governments and establishing a 5 billion euro special fund for grid upgrades.

The April blackout in Spain and Portugal demonstrated that when 15GW of power disappears from the system within five seconds, even the most advanced PV systems cannot prevent grid collapse. Germany's electricity prices surging 175% during heatwave peaks revealed the cost of delayed ESS deployment.

Europe's energy transition stands at a critical juncture. As Germany and nine nations push for establishing a PV raw material strategic reserve and prepare to review the 5 billion euro grid upgrade fund, the continent's energy future not concerns its 215GW PV target but also determines whether the world can build an energy system that is both clean and resilient amid climate crises.

References:

1. Germany's PV installed capacity exceeds 107.5GW https://m.solarbe.com/21-0-391121-1.html
2. Heatwave pressures European grids, brings profits to ESS operators https://chuneng.in-en.com/html/chunengy-46483.shtml
3. European heatwave triggers electricity price surge!Decline in nuclear power plant capacity, solar energy emerges as a savior https://19fyc00004.iyp.tw/news-detail-3935480.html
4. Europe collectively experiences power outages: System vulnerability exposed amidst energy transition pains https://www.hyqqw.com/article/102055.html
5. 46℃! Europe suffers from "heatstroke shock," with economic turmoil and social rifts emerging simultaneously... https://news.10jqka.com.cn/20250703/c669376156.shtml
6. Lessons from Europe's major power outages: Special emphasis should be placed on increasing the installed capacity of technologies such as solar thermal power generation and compressed air energy storage (ESS) _power grid_ backup _ Spain https://www.sohu.com/a/891282145_121123906
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