Solar Eclipse May Affect Solar Generation but Not Grid Reliability


PJM routinely prepares for the typical events that could impact the grid, such as severe storms and heat waves. Every once in a while, something a little out of the ordinary comes along. On August 21, that will be a solar eclipse, which will obscure the sun in the middle of the day as it passes over the region served by PJM.  The impact is that when the moon blocks the sun, solar generators lose their fuel source for that period of time.

Although solar generators may be impacted by the eclipse, no reliability issues are anticipated.

Joe Mulhern, senior engineer – Generation, described the solar eclipse event at a recent Operating Committee meeting and discussed PJM’s plans to prepare.  If August 21 is a sunny day, PJM could need about a 2,500-megawatt increase of non-solar generation to replace solar generation.

PJM will ensure there are sufficient resource commitments to replace any expected generation loss and will refine its analysis prior to the event to factor in the latest weather forecasts.

PJM’s estimate of solar generation potentially affected came from the Generator Attribute Tracking System. The GATS data identified how much solar generation is within certain geographic areas.

North Carolina could see the greatest impact to photovoltaic resources and system operations. PJM is also closely watching the state of New Jersey, which has more solar generation than most of the other states within PJM.

Mulhern stressed that in its analysis, the North American Electric Reliability Corporation found no reliability impacts to bulk power system operations nationwide, including places such as California with more solar generation than PJM. He said this event will provide valuable lessons to apply to another anticipated eclipse in 2024 and likely more solar generation in the PJM footprint.