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Interconnection Standards

Savings Category 
Fuel Cells
Program Info
Program Type 
Vermont Public Service Board

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 photovoltaic (PV) systems, wind-energy systems, fuel cells or biomass-energy systems until the cumulative generating capacity of net-metered systems equals 4% of a utility's peak demand. The maximum system capacity for net metered systems is 500 kilowatts (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 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 Electronic 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.
* System owners must carry a minimum of $100,000 in general liability insurance for residential systems and $300,000 for non-residential sites.
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 10 kW (AC) or Less in Capacity," both of which are available on the Public Service Board's [ website].
'''Interconnection Standards for Other Systems'''

In 2005, Vermont enacted legislation (Act 61) that established a statewide renewable portfolio goal 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 distributed-generation (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 nonrefundable 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.