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2017 Solar Eclipse

August 31, 2017

Ontario experienced a partial solar eclipse on Monday, August 21, 2017, between 1:10 p.m. EDT and 3:50 p.m. EDT. This celestial event was unique as it is the first solar eclipse to take place since large amounts of solar generation has been installed across North America.

Leading up to the eclipse, the IESO planned extensively and communicated widely with Ontario electricity sector partners, including its interconnected neighbours and weather and solar forecasters, to plan the day’s power system operations accordingly.

At its peak, which occurred at around 2:33 p.m. EDT, the IESO saw a 67-percent reduction in solar generation output, for a total reduction of about 1,220 MW. Solar generation connected to distribution systems was reduced to 490 MW from 1,470 MW, and solar generation connected to the transmission system went down to 115 MW from approximately 350 MW.

Demand remained relatively flat during the eclipse. There were no power system reliability issues in Ontario.

 More information is available on the IESO website.

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