German TSOs prepare for 4.2 GW hit from partial solar eclipse June 10

German transmission system operators expect a partial solar eclipse on June 10 to reduce solar generation by around 4.2 GW, TSO Amprion said.

The partial eclipse would impact Northern Europe with a maximum 20% of the sun covered by the moon across northern Germany between 11:20 and 13:40 local time, the TSO said.

Across southern Germany, only 2.5% of the sun would be covered.

"Contrary to 2015, special operating concepts are not necessary as the deviation will not be that great," Amprion said.

In March 2015, a total eclipse impacted solar generation across Europe.

A more detailed analysis would be given on the day before the partial eclipse, based on the latest weather forecast. At the moment little cloud coverage is expected.

System operators have planned for months for the event and will be in constant contact during the eclipse, ready to implement planned measures.

Around two-thirds of German solar is marketed through grid operators, with the remainder sold via direct marketing.

Day-ahead forecasts often require adjustment in intra-day markets before balancing markets finetune supply and demand close to realtime.

TSOs have tendered for an additional 500 MW secondary reserve capacity to either ramp up or down as well as 500 MW minute reserve, Amprion said.

Current installed solar capacity of 56 GW is some 20 GW higher than at the time of the March 2015 eclipse.

German intra-day market volatility was high during the March 2015 eclipse, especially during the ramp-up when the sun re-emerged with solar output increasing more than 15 GW in one hour.

The next major but still partial eclipse in 2025 could pose a bigger challenge, while the next total eclipse is expected 2090, according to the Royal Observatory.

S&P Global Platts Analytics forecasts solar capacity to reach 214 GW in 2025 across the 10 European markets covered by its five-year forecast, up from 148 GW currently installed, with Germany accounting for over a third.