Great Britain is offering free electricity to households that reduce consumption during the solar eclipse. While many are eagerly awaiting the eclipse, it creates a certain “headache” for solar energy. Energy suppliers and grid operators are preparing for the possible impact of the phenomenon on solar power generation.
On Wednesday, August 12, the Sun will be partially obscured over most of Western Europe. Significant areas of Spain and smaller parts of Portugal, Greenland, and Iceland will experience a total solar eclipse. Since solar energy is an important component of Europe’s energy balance and accounted for about 13% of electricity production in the EU in 2025, the two-hour event could disrupt generation balance.
Spain and Europe prepare for reduced generation
In Spain, solar energy accounts for an even larger share of electricity generation — from 21% to 22%. As a significant part of the country will experience a total eclipse, Spain may be particularly hard hit. The Spanish grid operator Red Eléctrica de España (REE) has announced precautionary measures to counter the expected impact on photovoltaic generation, which it predicts will be “limited and temporary”.
The eclipse will occur in Europe in the early evening when solar power production naturally begins to decline. At the same time, according to REE calculations, it could lead to a reduction in generation on the Iberian Peninsula of up to 5 GW — approximately 13% of peak demand for a typical mid-August. REE is closely coordinating with government agencies, other European transmission system operators (TSOs), as well as national generation and distribution control centers. The operator is also increasing reserve volumes and system strength margins and continuously monitoring the situation. According to the European Network of Transmission System Operators for Electricity (ENTSO-E), solar power production across Europe could drop by 9.7 GW.
Britons encouraged to save electricity
In Great Britain, a major household electricity supplier Octopus Energy is taking an unusual approach to the problem, encouraging customers to join a campaign to reduce consumption during the eclipse. “When the sun disappears from the energy system, we want you to do the same,” the campaign states. Households that consume less electricity during the eclipse than usual will receive an hour of free electricity on Sunday as a reward.
The amount of free electricity will be limited to 16 kWh — “more than any ordinary home could use in an hour (more like lighting a small sports stadium!)”, states Octopus Energy. To participate, customers need to register for the company’s rewards program.
Octopus‘s offer is not just a publicity stunt. For the grid frequency to remain within a safe operating range and to avoid blackouts, electricity production and consumption in real time must remain balanced. If households simultaneously reduce consumption with the decline in renewable energy production, it could reduce the need to start gas power plants to compensate for the deficit.
The company hopes its initiative will reduce the strain on the grid, as the eclipse could lead to the loss of “a huge chunk of Britain’s solar generation — just as millions of people return home and electricity demand surges sharply.” Demand for electricity for cooling could be particularly high this week as Britain experiences its fifth heatwave of the year. At the same time, according to the National Electricity System Operator of Great Britain (NESO), demand could fall below normal levels during the eclipse as millions of people go outside to observe the phenomenon. The Moon is expected to cover up to 95% of the solar disk over parts of Great Britain on Wednesday evening.
Portugal mobilizes additional reserves
The operator of Portugal’s electricity grid Redes Energéticas Nacionais (REN) expects to have to deploy additional energy reserves to compensate for the loss of solar generation caused by the eclipse. In a statement released on Monday (August 10), the company noted that to restore the balance of demand and supply in the National Energy System, it will have to mobilize “additional hydro and/or thermal generation reserves.”
This is also necessary to maintain the stability of the interconnection between the Portuguese and Spanish electricity grids. REN forecasts a drop in solar power production of 450 MW, which is about 7% of consumption and 45% of the average forecasted solar power production in the time slot from 18:30 to 20:30. In Portugal, the eclipse will be “almost complete”: its maximum phase will range from 92% in the Algarve to 100% in the municipality of Bragança.
Source: Euronews
