How the solar eclipse will affect grid stability

Get ready to dust off your Solar Viewer glasses because on April 8th, 2024, the US will witness a total solar eclipse, marking the first since 2017 and the last until 2044. This eclipse’s path of totality will cross North America, passing over Mexico, the central United States, and eastern Canada, casting approximately 4 minutes of darkness in areas along its path during the afternoon. 

Grid operators throughout the United States are outlining their strategies for managing the total solar eclipse, ensuring they accurately forecast how the eclipse might affect their power networks. Solar capacity has grown exponentially throughout the years and the amount of solar incorporated into the grid has increased by approximately 120 GW since 2017, raising the question: will the lack of sun during the eclipse cause problems for the grid? Fortunately, this total solar eclipse has been on the radar for quite some time now, and grid operators will balance demand and supply just as they do on days with cloud cover or rain.

However, let's dive in more because this is a fascinating topic to discuss since total eclipses do not happen every day. While the grid will most likely survive another day, there are risks and intriguing aspects to consider for April 8th that may highlight future grid vulnerabilities. 

Concerns about blackouts are very far-fetched given the time of day, time of year, and stability of the grid. April is still considered shoulder season, meaning demand is on the milder side for the regions affected. Although there are solar farms in the eclipse’s path, the temporary dimming of solar power for 4 minutes will not cause grid-wide blackouts. Ancillary services as well as the growth of renewables and battery storage since 2017 will strengthen grid resilience. Battery storage systems could even play a crucial role in alleviating grid stress during the solar fluctuations of the eclipse.

One notable risk is the potential for cloud cover, which reduces the dimming effect in certain regions. Locations closer to the central axis of the total eclipse offer the best viewing points for witnessing this event. Outside of this central axis, minor afternoon dimming is expected, but if cloud cover is widespread, unfortunately, this dimming might not be noticeable since solar generation could already be relatively low on that day. 

During moments of total darkness or near darkness, temperatures will drop. This is a similar concept to when temperatures decrease when the sun sets at night. The impact of this temperature drop may not be significant in places like the Northeast and Midwest where spring temperatures are generally mild. However, if initial morning temperatures are colder on this day due to weather conditions caused by a cooler-than-normal weather pattern, the dimming effect may lead to an increase in heating demand. On the flip side, in Northern Texas, average temperatures this time of year can range anywhere between 70 to 80 degrees Fahrenheit. A 5-10 degree temperature drop in this region could result in a refreshing cool down, altering the normal demand curve for the afternoon. In reality, most people in the path of the eclipse may not be inside consuming electricity at all during this time. They will be outside using their solar-viewer glasses to get that million-dollar shot!

In conclusion, the anticipated slight decrease in demand and temporary drop in solar generation during the hour of dimming and 4 minutes of total darkness are expected to have the most noticeable visual impact on the grid. While solar generation will decline, Amperon’s renewable forecasts, currently measured in hourly intervals, are anticipated to resemble typical days with isolated cloud cover. Below are examples of altered demand and solar curves from regions that experienced the dimming impact of the August 21st, 2017 total eclipse and the Annular Solar Eclipse that took place October 14th, 2023.  

*This shows the dip in solar from the Annular Solar Eclipse that took place October 14th, 2023. 

If you are interested in tracking the eclipse’s progress you can visit NASA's site.

Amperon incorporates all the latest weather information into its grid-level and meter-level forecasts so customers can plan with confidence and precision. Stay ahead of the game by consulting Amperon’s demand and net demand forecasts to prepare for the upcoming Solar Eclipse. You can contact us here.

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