Heat Puts Power Grids to the Test

June 30, 2026

Source: E & M powernews

The intense heat at the end of June caused electricity demand to rise. Consequently, the distribution grids were subjected to greater strain. Some were unable to withstand the load.

It has been almost exactly one year since Mainova reported the highest daily load to date in its service area. This figure exceeded 850 MW. At that time, on July 2, 2025, temperatures of 38.4 degrees Celsius were recorded in the Frankfurt am Main metropolitan area. In previous years, the peak daily power demand had been just over 800 MW.

Mainova Grid Withstands Daily Peak Load

Now, on June 27, 2026, an all-time high of 41.2 degrees was recorded in Frankfurt. The temperature had already risen above the 40-degree mark in the days leading up to that. The announcement from the municipal utility Mainova was not long in coming. On both June 25 and 26, the daily peak load in the Frankfurt metropolitan area climbed to more than 900 MW. A major reason for this was the very high temperatures, which led to a correspondingly high demand for cooling. Frankfurt am Main, a financial hub and home to a central European data hub, has one of the highest densities of data centers in Germany.

Peter Arnold expressed his “pride” that the distribution grid ensures a reliable supply even under “extreme conditions.” The substantial investments in the grid have paid off accordingly and will be further increased, according to the Mainova executive board member. According to Arnold, a total of 900 million euros is to be invested over the next five years to double the capacity of the power grid.

Incidents in Rüsselsheim, Lahr, and Fürth

The grids of other energy companies, however, proved less resilient in recent days. Stadtwerke Rüsselsheim, also in Hesse, reported a power outage late in the evening on June 25 that affected approximately 2,000 households in its service area. A combination of several factors led to the outage. “The exceptionally high temperatures of the past few days caused very high electricity demand. In addition, the grid was subjected to extra strain that evening,
among other things, due to the World Cup match taking place at the same time,” the utility reported. It was referring to Germany’s soccer match against Ecuador; five days later, Paraguay knocked the German national team out of the World Cup.

According to the Rüsselsheim-based company, the high grid load on June 25 caused several pieces of equipment to fail, primarily cable joints—that is, connecting elements. The resulting ground faults triggered a chain reaction and ultimately led to a widespread outage.

Unusual Cluster of Equipment Failures

“Individual defects in connection elements occur time and again in a power grid. However, it is exceptional for multiple pieces of equipment to fail almost simultaneously, with the effects reinforcing one another,” explained Maik Landwehr, managing director of Rüsselsheim’s municipal utility.

In Lahr, Baden, E-Werk Netze—a subsidiary of E-Werk Mittelbaden (EWM), which was known as Überlandwerk Mittelbaden (ÜWM) until 2025— reported a heat-related cable fault on June 26, which resulted in a power outage. However, the outage was resolved within just under 45 minutes.

In Fürth, Middle Franconia, there have been several power outages since June 26. “The record-breaking temperatures last weekend placed a heavy strain on the power grid in Fürth and led to an unusual cluster of cable faults in the medium-voltage grid. The districts of Hardhöhe, Poppenreuth, and Ronhof were affected,” according to the municipal utility. In some cases, the outages lasted only a few minutes.

In Ronhof, however, there were three initially unrelated cable failures on the afternoon of June 28, which then developed into a “complex major outage” lasting about four hours. According to Infra Fürth—the municipal utility’s official name—approximately 2,000 households were affected.

Author: Fritz Wilhelm