Close coordination among operators of Europe's interconnected electric power grid will be crucial to managing the potential loss of some 35,000 megawatts (MW) of solar photovoltaic (PV) generating capacity during a two-hour solar eclipse that takes place on the morning of March 20.

Managing this event on one of the world's largest interconnected electric power grids is an unprecedented challenge for European transmission system operators (TSOs), says the European Network for Transmission System Operators for Electricity (ENTSO-E). Solar eclipses have happened before, but with the increase of installed PV energy generation, the risk of an incident "could be serious without appropriate countermeasures," ENTSO-E says.

The main conclusion of ENTSO-E's Solar Eclipse Impact Analysis is that operational coordination among European TSOs will be crucial. After operational planning work, TSOs will put in place continuous on-line coordination between control rooms across Europe ahead of and during the eclipse to better coordinate the scheduled remedial actions.

ENTSO-E says that the solar eclipse is a "perfect illustration that maintaining system security with more and more volatile and dispersed generation is becoming increasingly challenging."

In several reports, policy and position papers, ENTSO-E says it has pointed out that in order to guarantee security of supply, a series of policy and regulatory changes are needed to take into account the evolution of Europe's energy mix.

The last solar eclipse in Europe took place in 1999. According to European statistics, solar power amounted to 0.1% of all the electricity produced in Europe from renewable energy sources in 2002. More than 10 years later, this figure stands at 10.5%. In the continental Europe area alone, 3% of all the electricity consumption is from PV generation. In 2015 the installed capacity on PV in the synchronous region of Continental Europe is around 90 GW and the eclipse may potentially cause a reduction of the PV infeed by more than 30 GW during clear sky conditions.

ENTSO-E says that what makes this year’s solar eclipse so special is the fact that there is now a "non-negligible amount of energy generation units connected to the grid that are highly sensitive to variations in solar radiation."

TSOs have not designed specific countermeasures for the eclipse, ENTSO-E says. Instead, they will use "the usual countermeasures TSOs resort to in order to operate their systems." The main difference is that in view of thev particular challenge that the solar eclipse represents for the continental European power system, the countermeasures might be activated more rapidly than usual.

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