PJM Provides Update on Preparations Ahead of April 8 Total Solar Eclipse


PJM provided an update on its preparations to manage the possible effects on generation and load as a result of the total solar eclipse set to impact most of PJM’s footprint from about 2–4 p.m. on April 8.

PJM’s latest update (PDF) at the April 3 Market Implementation Committee was informed by a weather forecast predicting relatively mild temperatures for the time of year and a partly cloudy day.

Much of Ohio and parts of western Pennsylvania are within the 122-mile-wide “path of totality,” when the moon will entirely block the sun for two minutes. While sharing preliminary expectations for a relatively mild afternoon, PJM is prepared to maintain reliable grid operations through changes in solar generation output tied to various weather scenarios, said Kevin Hatch, Sr. Manager – Dispatch.

“We have come up with different operational strategies,” Hatch said, ranging from clear skies that would impact the most solar generation to a stormy day with minimal impacts.

Expected Solar Generation Reductions and Load Increases

Taking into account the partly cloudy weather forecast, PJM is preparing for a temporary reduction of at least 85% to 100% of the production from the grid-connected or metered solar resources in its fleet. To date, PJM predicts reductions of about 4,800 MW of grid-connected solar generation that would have been available absent the eclipse.

At the same time, PJM expects load, or electricity demand, to increase on the order of an estimated 4,200 MW of generation, reduced from behind-the-meter solar, said Michael Stewart, Sr. Engineer – Load Forecasting – Markets Coordination.

The anticipated temperatures in the mid-60s are not expected to spur demand from heating or cooling, he said.

“This is the sweet spot,” he said. “We are not hot enough to cool anything. We are not cold enough to warm anything. No significant load change to that.”

PJM anticipates potential minor impacts to the overall forecasted load for the day due to school closures (less demand) or behavior tied to eclipse tourism (both rise or fall in demand based on location). However, this type of consumer behavior is not expected to impact loads during the actual eclipse event, he said.

PJM’s Preparations Ahead of the Eclipse

In the April 3 presentation, Hatch also described PJM actions to make fast-start generation resources available to ramp quickly when called upon if needed to maintain system frequency by replacing lost solar power.

PJM has prepared eclipse-day plans in close consultation with neighboring grid operators. Steps taken for April 8 include:

  • Deferral of planned maintenance generation outages for fast-start resources such as combustion turbine engines
  • Plans to manage transmission congestion impacts caused by generation losses and replacement generation
  • Production freeze to PJM system changes
  • Doubling regulation reserves for event duration
  • Coordination with hydro generation resources to be available for ramping needs as needed

PJM’s forecast is subject to change with weather updates closer to April 8. PJM previously presented on the solar eclipse at the March 7 meeting of the PJM Operating Committee. Read more about the eclipse on the NASA eclipse page.