Interconnection Standards

Vermont has adopted separate interconnection standards for net-metered energy systems that are 150 kW or less, and for all other distributed generation (DG) systems.

Interconnection Standards for Net-Metered Systems 150 kW or less

Vermont requires electric utilities to offer net metering to all customers with solar photovoltaic (PV) systems, wind energy systems, fuel cells, or biomass energy systems.  The maximum system capacity for net-metered systems is 500 kW. Interconnection of net-metered systems rated 150 kW or less are subject to the requirements described Appendix A of the net metering rules (5.100).

Net-metered solar PV systems must conform to applicable electrical safety, power quality, and interconnection requirements established by the National Electrical Code (NEC), the Institute of Electrical and Electronics Engineers (IEEE), and Underwriters Laboratories (UL). A utility may not charge additional standby, capacity, or interconnection fees, or fees or charges other than the customary minimum monthly fee.

The following key provisions apply to all net-metered, interconnected systems 150 kW or less:

• All systems must have a utility-accessible, lockable disconnect switch -- unless the system is inverter based and the utility has waived the requirement in writing, and in the case of small systems (less than 500 watts), where a lockable disconnect plug unit is acceptable if the customer files a proper application with the utility. The disconnect plug must be able to break load and must be utility-accessible.
• Systems will be tested initially upon installation and once every two years to determine that anti-islanding controls are functioning correctly.

Net-metered systems must first complete an application for a "Certificate of Public Good for Interconnected Net Metered Power Systems," or register as a "Photovoltaic Systems that Are 15 kW (AC) or Less in Capacity," both of which are available on the Public Service Board (PSB)'s website.

Interconnection Standards for Other Systems

In 2005, Vermont enacted legislation (Act 61) that established a statewide renewable portfolio goal (this goal has since been repealed and replaced with a Renewable Energy Standard) and required the PSB to develop interconnection standards for DG up to 50 megawatts (MW) in capacity -- unless the PSB establishes a lower capacity in order to avoid federal preemption. In 2006, the PSB adopted interconnection standards for DG systems that are not net metered and not subject to Independent System Operator of New England (ISO-NE) interconnection rules or successor rules approved by the Federal Energy Regulatory Commission (FERC). These rules also apply to net-metered systems larger than 150 kW but smaller than 500 kW. Under this rule, utilities are required to designate an employee or office from which customers may obtain information regarding the application process. There is a standard application form and a non-refundable application fee of $300. The PSB's DG interconnection rule does not specify a maximum system capacity.

DG systems that meet certain technical screening criteria are eligible for the "fast track" interconnection process, which requires no special studies. Systems not eligible for "fast track" interconnection require a feasibility study, a system-impact study, and/or a facilities study. Reasonable, specific timelines apply to "fast track" interconnection and general interconnection. During the interconnection process, either party may petition the PSB for resolution of a dispute.

A manual external disconnect switch is required. Systems must comply with an array of standards, including IEEE 1547 and UL 1741. Any equipment package will be considered certified for interconnection if it has been submitted, tested, and listed by a nationally recognized testing and certification laboratory or approved by the U.S. Department of Energy.

The PSB has developed model interconnection documents, including a feasibility study agreement, a system impact study agreement, a facilities study agreement, an interconnection agreement, technical requirements, and operator protocols. However, a customer and utility may also enter voluntarily into different arrangements.