Meter socket adapters are approved by 86 utilities across 33 states

A new device called a meter socket adapter (MSA) is now approved for customer use by 86 utilities in 33 states, according to a regulatory filing from Efficiency Maine Trust, the Maine Office of the Public Advocate, and consultancy EquinoxDG. An MSA attaches to your home's electric meter socket and connects to solar panels, a battery, or an EV charger, bypassing the main electrical panel. That can save you from a costly panel upgrade when adding this kind of equipment. Even where a state allows MSAs, not every local utility does. Maine is one example: the state's utility CMP has raised safety concerns, though device certification to a safety standard called UL 414 is meant to address that.

The filing argues MSAs matter most for home batteries. In Maine, using a Tesla MSA for a battery installation reportedly saves about $700 in parts and two or more hours of electrician labor compared with other approved wiring methods. Lower installation costs make programs like Efficiency Maine's small battery incentive more worthwhile for homeowners, since batteries can earn money by sending power back to the grid at peak times.

As an example, Efficiency Maine projects that a customer using 600 kWh a month who installs a 15 kWh, $20,000 battery could earn about $500 a year in grid-sharing payments plus $500 a year in savings by shifting usage to cheaper off-peak hours, cutting the battery's net cost in half over ten years. A household with higher usage, such as one with an EV and a heat pump, could see similar savings with a larger, 30 kWh battery. Whether any of this applies to you depends on what your own state and utility currently allow, so it's worth checking local rules before planning a battery or solar installation.