Burst of New Solar Power Makes Midwest Grid the Biggest in US

Growing solar power in a swath of the US Midwest dominated by Republican leadership has led that region’s electric grid to become the nation’s biggest in terms of electric supply.

The Midcontinent Independent System Operator, which provides power to 45 million people in 15 states including Indiana and Missouri, overtook PJM Interconnection LLC, according to a report from BloombergNEF. Until last year, PJM, a sprawling grid stretching from Washington, DC, to Chicago, held the top spot.

MISO added 7.45 gigawatts of solar power between April 2024 and this past March, compared with 3 gigawatts at PJM. Illinois, a Blue state, accounted for the largest share of MISO’s buildout. GOP-led Indiana, Arkansas and Missouri were next.

The expansion has continued despite President Donald Trump’s opposition to solar and other renewable energy. His administration has ended federal tax credits for solar installations and imposed permitting delays.

Rising electricity prices and fears of a power crunch, driven largely by surging demand from AI data centers and extreme heat, have made expanding grid capacity a top priority for both utilities and politicians.

Both MISO and PJM have experienced high demand this summer. Power demand on PJM’s system likely broke a 20-year-old record in early July, the operator said.

Solar units built on the Midwestern grid since early 2024 had nearly twice the average size of those added in the Mid-Atlantic, according to BNEF’s report. Even though slightly more solar units were built in PJM, MISO added more capacity overall.

In total, MISO’s generation capacity was 230 gigawatts at the end of the first quarter, exceeding PJM’s 227 gigawatts.