What to Expect: Solar Generation and Electricity Demand Impacts

The August 21 solar eclipse is expected to take place between 1 to 4 pm, with the peak of the eclipse occurring around 2:30 pm. Typically, at this time of day during the summer months, Ontario’s demand for electricity is near its highest of the year, and solar panels in the province are near their peak output.

The graph below shows forecasted electricity demand for a typical summer day – and how demand could be impacted with the potential reduction in solar generation and increase in lighting load at the time of the eclipse.

The partial solar eclipse we’ll see in Ontario, on a sunny, clear day is expected to reduce electricity output from solar generators by approximately 70 percent. There will likely be an increase in electricity demand due to homes and businesses turning on additional lighting to make up for darkening skies. The IESO will be ready to call on other flexible generation resources to help meet these changes in Ontario electricity demands.

The IESO will be actively monitoring weather and demand forecasts for the days and hours ahead to ensure smooth operations in the control room for Ontario’s bulk power system, and reliable service for Ontario consumers.