Solar Eclipse Stress Test to European Power Grids

solar eclipseSolar eclipse over Europe March 20, 2015 (source: Reuters)


Animal behaviors in reaction to the onset of a solar eclipse are observable and quite well known. Hippos, for example, leave their resting place and head toward the river bank, preparing to submerge into the water to traverse the bottom of the river to graze beyond its banks, and get pretty confused when the sun emerges again before they get to the riverbank. Most bird calls cease at the height of an eclipse – opposite is true for owls. Impala seem to appear skittish and alert following an eclipse.

As it turns out, it is not only the animal world which worries about such an infrequent planetary phenomenon. Power utilities across Europe had good reasons to be nervous about the partial solar eclipse observable on the continent on March 20.

With 89 gigawatt (GW) of installed solar capacity, utilities all over Europe were worried that the rapid shutdown and subsequent ramp-up of solar power production during the eclipse would be too much for the power grid to handle. Italy’s Terna, for one, decided to switch off 30 percent of its solar capacity as a precaution.

Germany, which represents the lion’s share of Europe’s solar capacity, decided to take the event head-on by preparing months ahead of time and putting on extra staff during the eclipse to better react and manage anything that might come up.

The Solar Stress Test

Unlike the series of stress tests the ECB conducted on European banks using marked-to-myth accounting methods which were anything but stressful, this stress test brought to the continent by the white dwarf is the real Macoy.

But first a few factoids about Germany’s solar power.

  • 38.2 GW of installed capacity from 1.4 million solar systems.
  • Produces nearly 7 percent of the nation’s electricity (by comparison solar provides 0.5% in the US).
  • Satisfies up to half of the nation’s power demand during the sunniest hours.

Disruption to solar generated power during eclipse

Rapid decrease and subsequent equally rapid rise in solar power caused by an eclipse (source: Greentech Media)

During the two and a half hour event which saw up to 75% of the sun covered by the moon, German power output dropped from 21.7 GW to a low point of 6.2 GW and then shot up another 15 GW during the event. The ramp-up and ramp-down phases were almost three times as steep as on normal days, and would have had the equivalent effect of shutting down a medium size power plant every minute for a full hour.

And the result?

The (nice) surprise is, there is no surprise.

Nothing bad happened, that is. Through thorough preparation, the German power grid came through with flying colors.

Challenges with Intermittent Power Supply

This latest planetary episode provides an early glimpse of the challenges placed on our power supply as more renewable but intermittent energy sources are brought online and fed into the power grid. In particular, the future grid needs to be intelligent, flexible and reliable in order to handle the wild swings in solar power supply brought on by eclipses and the more common cloud covers. This challenge will intensify as solar energy hits the proverbial hockey stick of the mass adoption curve, thanks to the dramatic drop in production cost enabling solar to reach grid parity in many parts of the world.

To accommodate potential dramatic swings and the rapid ramp-up and ramp-down phases of power production, a new set of supply as well as demand responses will have to be incorporate into the emerging intelligent grid. Emerging technologies such as solar plus storage, distributed generation and intelligent power networks enabling the transition toward renewable energy will be areas of rapid innovation and economic opportunities for the next decades.





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