The generation of renewable energies is being vigorously promoted. However, a large part of the energy is lost again due to curtailments. “This is both a regular and a huge waste“, comments Patrick Lemcke-Braselmann, Co-CEO of aream Group SE. At the same time, he says, the solutions to problems such as grid overloads and lack of flexibility are well known.

Actually, the weather in August was quite decent. With around 253 hours of sunshine, the sun shone over Germany for almost a fifth longer than in the same period from 1991 to 2020, according to the German Weather Service. Since comprehensive measurements of sunshine duration began in 1951, August 2025 ranks among the ten sunniest months on record. 

However, the photovoltaic systems in the aream portfolio were only able to benefit from this to a limited extent. “Potential good yields were prevented by curtailments of around 1,000 megawatt hours“, explains Lemcke-Braselmann. The target was only achieved by 91 per cent. The situation was similar in Spain, where the plants only achieved 71 per cent of their target. “There, too, the stable performance with average irradiation values was not translated into higher yields“, says Lemcke-Braselmann. Curtailments occurred almost daily.  

The curtailment of photovoltaic systems is a key issue in Germany's energy transition. Especially in sunny months, too much solar power can overload the grid – and conventional power plants are often not flexible enough to compensate for the fluctuations. With the ongoing expansion of solar installations in Germany, overcapacities have arisen that are pushing the grid to the limits of its capacity. 

An additional challenge is posed by the Solar Peak Act, which does not provide for any remuneration for energy fed into the grid when electricity prices are negative. This leads to a de facto curtailment of the market and negative effects for operators of solar installations. Grid operators are therefore forced to throttle feed-in capacity in order to ensure grid stability. 

This means we need to speed up the expansion of the grid infrastructure. It would also be helpful to link sectors – for example, by using surplus electricity for heating or electric mobility – and to expand modern battery storage. “In the long term, this could ensure maximum use of renewable energies and reduce curtailments to a minimum“, says Lemcke-Braselmann. 

The Italian plants in the aream portfolio, on the other hand, are hardly affected by curtailments: ”This market differs from others in that it has several electricity price zones and greater flexibility, such as a high penetration of smart meters”, says Lemcke-Braselmann. With slightly below-average irradiation values, the Italian plants therefore delivered stable performance (target achievement: 91 per cent). The German wind turbines in the aream portfolio only achieved 74 per cent of their target. ”Wind conditions were also very weak in August”, explains Lemcke-Braselmann. Strong regional fluctuations led to results between 50 per cent and 90 per cent of the target.