Distributed solar interconnection timelines stretch to nearly four years for larger projects

If you're thinking about adding solar to your house, the timeline news is good. A new analysis from Lawrence Berkeley National Laboratory, which looked at more than 2.7 million interconnection applications across 188 utilities in 24 states, found that small solar systems under 30 kW — the size typical of a home rooftop system — got permission to operate from the utility in a median of two months between 2020 and 2025. That's the step where the utility signs off on connecting your panels to the grid. Larger projects fare much worse: timelines stretch to 9 months for systems between 30 and 100 kW, 16 months for 100 to 500 kW, and up to 45 months for projects between 1 and 5 megawatts.

Where you live matters too. Looking at the five states with the biggest sample sizes, the study found that for projects under 50 kW, median wait times ran about 2.3 to 3.1 months in Washington, New York, Arizona, and Rhode Island, but 6.4 months in Massachusetts. The gaps grow sharply for bigger systems, with Washington and Arizona processing them in 6 to 9.4 months versus 16 to 18 months in New York, Rhode Island, and Massachusetts.

There's also some evidence utilities are getting faster overall: the average time to finalize interconnection agreements dropped 26% from 2020 to 2025. But projects larger than 100 kW are still far more likely to get stuck in the pipeline than small residential systems, which continue to move through fairly quickly regardless of state.