PJM Sees Impact on Solar Generation during August Eclipse


PJM and its members ensured reliable power supplies throughout the Aug. 21 solar eclipse.

PJM recorded a drop of approximately 520 megawatts of wholesale solar generation from before the eclipse until the peak of the eclipse.

In addition, PJM also estimated that electricity from behind-the-meter solar generation (mostly rooftop solar panels that offset load) decreased by approximately 1,700 MW.

PJM had expected a reduction in power from rooftop panels to result in an increase in electric demand on the grid. However, because of a variety of potential factors, including reduced air conditioning, increased cloud cover and changes in human behavior related to the event, PJM recorded a net decrease in demand for electricity of about 5,000 MW throughout the eclipse.

The PJM footprint experienced an average temperature decrease of about 2 degrees Fahrenheit through the duration of the eclipse. The Chicago area also experienced storms after the eclipse’s onset.

PJM will continue to study the impact of the solar eclipse on its system. PJM will integrate lessons learned from the Aug. 21 event into preparing for the next solar eclipse, predicted to occur in 2024, when the grid is expected to have more solar generation.

PJM’s established planning, operations and markets functions have produced a reliable, diverse resource mix that includes natural gas, coal, nuclear, renewables and demand response that enabled PJM to maintain reliability throughout the eclipse. Solar generation currently comprises less than 1 percent of PJM’s 185,000 MW of generation capacity.

PJM will present a more detailed analysis of the Aug. 21 solar eclipse at its next Operating Committee meeting Sept. 12.