The North Carolina interconnection fast track is the path most commercial solar projects in the state take onto the grid, and understanding where its boundaries sit is the difference between an agreement in weeks and a study that runs for a season. The North Carolina Interconnection Procedures, approved by the North Carolina Utilities Commission in Docket E-100, Sub 101 and applied by Duke Energy Carolinas and Duke Energy Progress to customer-owned generation, set out three routes. A simplified process serves certified inverter-based systems up to 20 kW. A fast track with technical screens serves certified systems up to a limit that depends on the line at the point of interconnection, with an upper bound of 2 MW. Everything else goes to a full study.
Which route a project takes is decided at design, by the size of the system, the voltage of the line it connects to and the condition of that circuit. None of those is a surprise if the engineering is done first.
What are the three interconnection processes in North Carolina?
The 20 kW inverter process is the simplest. It applies to certified inverter-based generating facilities no larger than 20 kW and runs on a short application and a certificate of completion. A small office, a farm outbuilding or a retail unit fits it. Most of the commercial systems we design do not, because a facility with a meaningful power bill needs more than 20 kW to move it.
The fast track process is the working route for commercial projects. It is open to certified generating facilities up to the size limits in the procedures, which scale with the voltage of the line at the point of interconnection up to 2 MW. Instead of a study, the utility applies a set of technical screens to the request: how the generator's output compares with the load on the circuit, what else is connected to the feeder, how far the site is from the substation and whether the equipment carries the required certification. A project that passes moves to an interconnection agreement. One that does not passes into supplemental review, where the utility examines the circuit more closely, and if it still cannot be approved, into the study process.
The study process is for projects that do not qualify for the first two routes or fail their screens. It carries a deposit, a longer timeline and the possibility of upgrade costs on the utility's side that the customer funds. It is not a bad outcome for a large project on a strong circuit, but it is a slow one, and it is the path to avoid for a project that could have fit the fast track with a different design.
What this means for a business planning a system in Duke territory
Three decisions made early keep a project on the fast track. The first is size. A system designed to the facility's load and to the interconnection limit of its line, rather than to the roof area, stays inside the screens. The second is the point of interconnection. Where a site has more than one service, or a choice between a lower-voltage and a higher-voltage connection, the choice changes which limit applies. The third is certification and controls: equipment listed to the standards the procedures name, and export limits documented in the application, so the utility is screening the system as it will run.
The cost of getting this right is a few hours of engineering. The cost of getting it wrong is measured in months, and sometimes in upgrade charges nobody budgeted. We have written about the rate side of Duke territory in what the Duke Energy Progress settlement means for a North Carolina business; the interconnection side is where the schedule is won.
Storage adds one more consideration. A battery added to an approved solar system later is an amended request, and the combined facility is screened again. Filing once with the full system described, even when the battery is a later phase, keeps the project inside the path it qualified for. Our approach to that pairing is on the commercial battery storage page.
How we handle interconnection in North Carolina
Our commercial solar installation in North Carolina is engineered by a professional engineer licensed in the state and an electrical contractor holding North Carolina's unlimited classification since 1992, with more than thirty years of work on utility interconnections behind the drawings. The interconnection application, the single-line diagram and the technical data sheet are produced in-house under one commercial solar EPC contract, and we screen the circuit ourselves before we file, so the utility's review confirms what we already know.
That discipline scales. On the 1.267 MW rooftop system at Samsonite and TUMI, the array and 55,000 pounds of storage were designed, permitted and built under one contract, which is the same discipline we bring to a 200 kW roof in Greensboro. The federal investment tax credit that helps pay for a project like it is claimed on the owner's return, and its conditions are on our federal solar tax credit page.
If your facility is in Duke Energy Carolinas or Duke Energy Progress territory and you want to know which interconnection path a system on your site would take, send us twelve months of utility bills and your service address. We will size the system to the load and the line, tell you which process it enters, and give you a schedule you can plan around.