This article was interesting in that it provided a somewhat technical report on how prepared PJM is for the summer weather. PJM is the largest electricity grid in the U.S., providing service in thirteen states, include PA. It's also the transmission operator for PECO in Philadelphia -- and I believe back in the 1920s started out as part of PECO.
The article stated that PJM is indeed ready for what the National Weather Service has anticipated will be a hot summer, and provided the "peak load" capacity: 155,000 MW. The highest peak on record for PJM was 165,000 MW in 2006. Energy forecasters don't believe this summer's peak will exceed 150,000 MW.
The provider was tested in late May during a stretch of days that exceeded 90s pushing peak demand to just under 116,000 MW on the 23rd.
Donna Rovins, "Region’s electric grid operator is ready to meet summer demand", contributed by Alison Kenner, The Energy Rights Project, Platform for Experimental Collaborative Ethnography, last modified 1 June 2021, accessed 29 November 2023. https://energyrights.info/content/region’s-electric-grid-operator-ready-meet-summer-demand