What is Interconnection?
Connecting your home's solar panel system to our electric grid is a process called interconnection.
Most residential solar installations operate in concert with our electric delivery system. This allows you as a solar homeowner to:
- Export (sell) excess energy to the electric grid when your system produces more than you use
- Purchase electricity from the grid when you need it
Your solar contractor (installer) and Eversource work together to ensure your system is safely interconnected and producing clean energy for your home or business. This starts when the installer first designs your system.
We require your installer to follow both state regulations and our detailed, technical guidelines when designing and interconnecting your new solar energy system. Because interconnection is a highly specialized process, you should choose a solar installer who is an electrician licensed to conduct business in the state and trained to perform this work.
Solar System Size
The size and complexity of your solar system dictate the type of interconnection your installer will follow. You might hear your installer talk about a “simplified” or “expedited” interconnection. These choices describe the type of application the installer submits and the associated guidelines and fees.
Most residential systems (15 kW or smaller) go through the simplified application process. If you're curious to learn more, you can review the detailed documentation that your solar installer must understand and follow when designing your system for interconnection.
Steps to Connect
At a high level, there are 3 steps in the interconnection process: initiation, construction and closeout.
1. Initiation: Your contractor submits an application on your behalf. We will review the application and send installation requirements to your contractor with approval to move forward.
2. Construction: Your solar system is installed which includes the inverter, the panels and the wiring for new meters.
3. Closeout: Your system will be inspected by the appropriate municipalities and your contractor will submit the requisite interconnection completion documents to Eversource. We will then install your new meters, issue a permission to operate (PTO) and start issuing your new net metering bills.
The interconnection process averages about 120 days from when your installer first applies. The timing of each step can vary significantly based your contractor’s ability to schedule installation work, timelines for municipal inspection of your new system and wiring, and scheduling of meter installation.
Solar Meter Installation
An Eversource technician will install new meters for your solar installation. This includes exchanging your existing utility meter for a net meter and, if you are participating in the Massachusetts SMART incentive program, a separate production meter to measure the output of your solar installation.
You are authorized to operate your system after the required meters are installed and we issue a PTO. Please consult with your solar installer to turn on your new system so you can start generating clean, renewable power.
There are minimal application fees for interconnection based on the size of your system (simplified or expedited interconnection). In addition, we might require an engineering analysis to determine if upgrades are needed to our electric grid to safely and reliably interconnect your new solar installation. If upgrades are required, you will be responsible for the cost of these upgrades which Eversource will construct on your behalf.
Typical residential systems do not have significant upgrade costs, however as more solar comes onto the grid, more grid upgrades will be needed in order to ensure power quality and reliability.