Vermont Green Mountain Power (GMP) Solar Interconnection: Rule 5.500 Screens, Timelines and Fees

Key Takeaways

• Rule 5.500 has no "fast track" label; its simplest screen covers Export Capacity of 15 kW or less and Nameplate Rating of 50 kW or less.
• Up to 15 kW, the ePUC net-metering registration is the interconnection application; above 15 kW you get GMP approval first.
• GMP must flag issues by the 15th day (Export Capacity 15 kW or less) or the 31st day (over 15 kW to 500 kW).
• No application fee at 150 kW or less unless a tariff provides one; GMP charges $37 per kW AC (TGFOV, affected circuits) and $110 for the production meter.

Rule 5.500 screens and deadlines for GMP customers

GMP states that "Any Green Mountain Power customer with metered service may participate," and Rule 5.100 confirms "The interconnection of all net-metering systems is governed by Commission Rule 5.500." We checked the sources on 6 September 2026.

There is no "fast track" in Rule 5.500

Rule 5.500 never uses "Fast Track," "Simplified," "Expedited," or "Level 1/2/3," and it never uses the word "tier." It is organized by section: Sec. 5.510 covers projects with a Nameplate Rating of 500 kW or less, Sec. 5.511 covers projects above 500 kW, and Secs. 5.513 to 5.515 set out the Feasibility, System Impact and Facilities studies. Within Sec. 5.510, the lightest screen, Sec. 5.510(C), applies to "Projects that have an Export Capacity not greater than 15 kW and a Nameplate Rating not greater than 50 kW," with three criteria: certified equipment, no connection to a transmission line, and no thermal overload of circuit equipment.

Everything else up to 500 kW gets the 14-criterion Preliminary Review under Sec. 5.512, completed "Within 30 days after an Application is determined to be complete"; one criterion caps protective devices at "87.5% of the short-circuit interrupting capability." Passing means written approval, and "Projects with a Nameplate Rating of less than 150 kW may interconnect without an Interconnection Agreement unless operating restrictions or requirements are identified."

Which filing route you use: ePUC registration or the 150 kW form

Rule 5.100 states: "For systems up to 15 kW, a registration form filed under this Rule constitutes a Rule 5.500 interconnection application." Above 15 kW, "the applicant must obtain interconnection approval from the electric company under Rule 5.500 before submitting" the CPG filing. GMP's process page mirrors this: 0 to 15 kW projects apply through the ePUC Net-Metering Registration, while >15 to 150 kW projects email the Rule 5.500 form to GMP and attach its approval letter to the CPG filing. A registration CPG is deemed issued on "the 15th day following the filing of the form," conditioned on meeting the utility's interconnection requirements.

Capacity means "the aggregate AC nameplate capacity of all inverters," and "The capacity of an inverter is not changed when it is derated." Every applicant supplies "Information regarding certification or Underwriters Laboratory listing" and "inverter settings, including inverter data sheets." The PUC's form page lists the 3/1/2024 version of the 150 kW form; download the current form from puc.vermont.gov before filing. GMP's process page has applicants send the completed form to its Distributed Resources team by email (the address is obscured on the page; the DER Guidelines give it as DR@GreenMountainPower.com), with a copy filed with the PUC clerk.

Utility deadlines: day 7, day 15, day 31

All Rule 5.500 windows are in plain days. The utility "must notify the Interconnection Requester within 7 days of the receipt of the Application if the Application is incomplete," with a written list of what is missing, then raise issues by "the 15th day following the date of receipt of a complete Application" for Export Capacity of 15 kW or less, or "the 31st day" for projects over 15 kW up to 500 kW. GMP's page puts its approval letter "by the 15th day for projects <=25kW or by the 31st day for projects >25kW following a completed application."

In a dispute, either party "may seek immediate resolution by written petition to the Commission," without losing queue position.

Fees, deposits and the $37/kW TGFOV charge

"Unless provided for in an approved Interconnecting Utility tariff, there is no fee for Projects" of 150 kW or less; above 150 kW "the fee is $600 or the amount specified in an approved Interconnecting Utility tariff," non-refundable "unless the Application is withdrawn within 7 days of submittal." An optional Pre-Application Report costs $300.

GMP's tariff adds two costs: on affected circuits, "The fee shall be $37/kW of installed AC capacity," and "15 kW systems and smaller shall pay the fee via the first electric bill after interconnection." For gross-generation metering, "The Company shall supply an additional meter at a cost to the Customer of $110." Rule 5.100 adds that the applicant "bears the costs of all equipment necessary to interconnect."

GMP equipment rules: certified inverters, disconnect switch, meter adaptors

GMP's Certified DER is "An inverter Certified to the requirements of UL 1741 SA (September 2016)" and compliant with the certifiable parts of IEEE 1547-2018 Clause 6; non-certified inverters are barred. The 150 kW form asks per inverter: "Is the inverter certified per UL 1741-SB and compliant with ISO-NE's Default IEEE 1547-2018 Setting Requirements?" For certified systems of 150 kW AC or less, anti-islanding needs only that "All inverters shall have an 88% voltage trip within 2 seconds."

The disconnect switch is a GMP requirement, not a form field: it "must be accessible to allow for use by first responders and lockable in the open position," with "direct 24/7 unencumbered access" for GMP. Export limiting requires a UL 1741-certified power control system with "a maximum open loop response time of no more than 30 seconds." GMP's August 2025 rules allow only six pre-approved meter socket adaptors, on 200 A sockets only.

Commissioning

"The Interconnecting Utility must be given 14 days' written notice, or as otherwise mutually agreed by the parties, of the tests," and GMP "reserves the right to witness the Customer's functional testing of the required devices, i.e., trip tests." Credit rates and adjustors are covered in our Vermont PUC Rule 5.100 guide.

What you can check yourself, and what you cannot

You can check the aggregate AC nameplate of your inverters against the 15 kW, 50 kW and 150 kW thresholds, confirm the UL 1741 SA/SB listing on the data sheet, and count the day-7, day-15 and day-31 deadlines from a complete application.

You cannot determine whether your circuit carries the TGFOV fee, whether protective devices already exceed 87.5% of interrupting capability, or whether GMP will impose operating restrictions. The disconnect, meter socket and AC tie-in need a licensed electrician.

What the published sources do not tell you

Neither Rule 5.500 nor the GMP tariff publishes a GMP-specific application fee for systems of 150 kW or less. The rules never say "business days"; Rule 5.100 points to Commission Rule 2.207 for time computation. No fetched document lists which circuits carry the $37/kW TGFOV fee, and insurance requirements appear nowhere in the rules, the DER Guidelines, the tariff, or the form. GMP's DER Guidelines are dated March 22, 2021 and predate the March 2024 rule revisions. The PUC's July 2025 guidance and GMP's page use a 25 kW threshold that the November 2024 Rule 5.100 text does not, so the ground-mount registration cut-off is unconfirmed. No source states how long an approval letter stays valid or a typical time to permission to operate.

Related Regulatory Guides

Compare New England procedures in our New Hampshire Eversource and Unitil guide and Maine CMP and Versant Power guide, and Vermont credit rates in the Rule 5.100 net-metering guide. Before filing, size your inverter with our solar sizing tool.