Indiana and Virginia have passed the first state laws in the country pushing utilities to use Surplus Interconnection Service, a mechanism that lets new generation or battery storage plug into the grid through unused connection capacity at an existing power plant instead of waiting in the standard queue, a process Pew Charitable Trusts says can take up to four years.
The mechanism works because most plants do not run at full output year-round. Wind and solar output shifts with the weather, and thermal plants built for peak demand or high fuel costs can sit unused for long stretches. Surplus Interconnection Service, or SIS, lets a battery or solar array share that idle capacity at an already-approved connection point, cutting the timeline to add power to months instead of years and avoiding the cost of new transmission lines, expenses utilities typically pass on to ratepayers. Federal rules have required grid operators to offer this option since 2023; Indiana and Virginia are the first states to pass laws encouraging its use.
| State | Law | Signed | Focus |
|---|---|---|---|
| Indiana | Senate Enrolled Act 240 | March 5 | All power plants |
| Virginia | S.B. 508, the FAST Act | April 22 | Solar farms plus battery storage |
Indiana covers every plant in the state
Senate Enrolled Act 240 requires Indiana utilities to evaluate their renewable and thermal plants for surplus interconnection opportunities. It applies statewide, where 40% of power plants generate electricity for less than four months a year, according to Pew Charitable Trusts. The bill passed both chambers of the legislature unanimously, and Governor Mike Braun (R) signed it on March 5. State Senator Eric Koch (R), who authored the bill, said the mechanism "is the fastest way to bring new resources online" and argued it protects ratepayers by reducing the need for new transmission lines. Indiana regulators plan further research into expanding the approach.
Virginia pairs solar farms with batteries
Virginia's S.B. 508, the Facilitating Access to Surplus Transmission Act, takes a narrower approach aimed at solar. It requires utilities to evaluate solar farms for battery storage additions and to run pilot programs installing batteries at the sites identified. Governor Abigail Spanberger (D) signed it on April 22. The goal is to turn solar farms into dispatchable resources: batteries charge during the day, when solar output is high and demand is often low, then discharge in the evening when demand rises after the sun goes down.
