The following article is a contribution to HSB’s Equipment Connection blog from experts at our parent company, Munich Re. While the partial eclipse due to occur on March 20th is of global interest, it is a possible concern to Germany, a country with a power grid that is very dependent on solar power.
There will be a partial solar eclipse on Friday, March 20th in Europe. It will be an exciting spectacle for observers, but what will it mean for our electricity network, which is increasingly supplied with electricity from photovoltaic systems?
At the time, there were futuristic-looking glasses to be seen on every street corner, and many people still have a pair lying at home to remind them: the last total solar eclipse on 11 August 1999 was a huge spectacle in some parts of Europe. On March 20th, it will be possible to observe another total solar eclipse over Europe. It will last for a maximum of 2 minutes and 47 seconds, with the narrow path of totality this time lying over the North Atlantic, the Faroe Islands and Spitzbergen. In many parts of Europe, the event will be experienced as a partial solar eclipse. In Munich, up to 70 percent of the sun will be covered.
A solar eclipse occurs when the Sun, Moon and Earth are in a line, and the Moon’s distance from the Earth is such that its shadow exactly covers the Sun.
The spectacle harbors a risk
When the Sun disappears behind the Moon between 8:40 a.m. and 12:50 p.m., as well as being an amazing sight, it will have repercussions on the European electricity grid. In theory, a photovoltaic plant achieves its maximum daily output at almost precisely the same time as the solar eclipse. These plants, which have an installed output of 90 gigawatts, now account for a substantial portion of the electricity production in the European grid. A scientific study carried out by the European Network of Transmission System Operators for Electricity (ENTSO-E) expects the solar eclipse to pose a risk for the electricity grid – whether the sky is overcast or cloud-free.
At very nearly the same time, if the sky is cloudless, over 30 gigawatts of power – the equivalent of approximately 30 nuclear power plants – will be removed from the electricity network. The effect will be much less if the sky is cloudy: in this instance, the proportion of solar power supplied will in any case be lower.
Slightly less than 50% of the drop in power will be caused by plants in Germany
Transmission system operators face the challenge on March 20th of compensating for these fluctuations in output. Network operators are preparing themselves, for example by securing additional balancing power from pump-storage power plants, to ensure that a stable network supply can be guaranteed. Neighboring countries, where fluctuations in the power grid occur at different times, or to a lesser degree, could also exchange power. Also available would be quickly controllable, flexible reserve power plants, such as gas-fired power stations.
So the reassuring result is that, thanks to the predictability of the solar eclipse, no real risk is expected for the stability of the network.
© 2015 Munich Re and The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is intended for information purposes only. HSB makes no warranties or representations as to the accuracy or completeness of the content of this article.