Commonwealth Fusion Systems Becomes First Fusion Company to Apply to PJM Interconnection Grid

On April 28, 2026, Commonwealth Fusion Systems (CFS) submitted an application to PJM Interconnection — the largest US wholesale electricity market with 182,000 MW capacity serving 65+ million customers across 13 states and Washington, D.C. — making CFS the first fusion energy company to formally apply to connect to a major US electricity grid. The application covers CFS's planned ARC commercial fusion power plant, which will build on the scientific demonstration provided by SPARC. SPARC is currently approximately 75% complete at CFS's Devens, Massachusetts campus, with first plasma targeted for 2027. CFS CEO Bob Mumgaard noted the application signals CFS is operating as a real power plant developer subject to FERC-regulated processes, not merely a research company. ARC is designed to deliver hundreds of megawatts to the grid, with commercial operations targeted in the early 2030s. The PJM application is a landmark commercial milestone for the fusion industry, demonstrating that the pathway from SPARC science demonstration to grid-connected commercial power plant is being actively executed — not just planned.