The Solar Electric Power Association

Position Statement on Photovoltaic Interconnection Issues in the U.S.


The Solar Electric Power Association, formerly the Utility PhotoVoltaic Group (UPVG) recommends that all electric utilities and other electric service providers implement uniform, simplified interconnection procedures for photovoltaic (PV) systems. Implementation of these procedures, covering both technical and contractual aspects of interconnection, is a crucial, reasonable, and timely step toward realizing the potential of clean, renewable, and reliable solar power. Inconsistent and, at times, inappropriate requirements for interconnection are creating unnecessary barriers to wider use of PV.

This Position Statement was developed and is being promoted to raise awareness and provide information useful to utilities, regulators, and others. This statement references important standards, new policies, and sample procedures that have been successfully implemented to simplify interconnection of these generation sources.

The Solar Electric Power Association s Position Statement on Interconnection consists of two companion documents. The first, Technical Aspects of PV Interconnection, explains how technical issues such as safety and power quality have been dealt with by standards-making bodies and how these standards have been implemented by utilities. The Association finds that three national standards: the Institute for Electrical and Electronic Engineers Recommended Practice 929-2000, the Underwriters Laboratories Test Procedure 1741, and the National Electrical Code Article 690, are sufficient to form a basis for uniform, simplified technical interconnection guidelines. Moreover, several utilities have successfully translated the standards into practical application. Substantial field experience confirms that these standards ensure safe operation of PV systems connected to the grid.

The second document, Contractual Aspects of PV Interconnection, highlights a number of issues that have been identified as barriers to wider use of PV. These issues include protocols for customer-utility interaction, insurance requirements, and fees, all of which need to be reviewed with a goal of reducing administrative burdens. The Solar Electric Power Association encourages all utilities to methodically simplify and streamline the contractual aspects of small PV system interconnection. Reducing costs associated with contractual aspects of PV interconnection is in the best interest of both customers and utilities.

Issues of metering, rates, and tariffs go beyond the scope of this position statement  they are tied in with a much broader range of issues. In this Position Statement, the Solar Electric Power Association hopes to obtain consensus on a smaller set of technical and contractual issues that will simplify PV system interconnection and promote wider use of clean, renewable, and reliable solar power. The debates over metering, rates, and tariffs can then take place without having to involve issues that, in most cases, can be straightforwardly resolved.

Interconnection issues will continue to grow in importance as other distributed generation technologies are brought to the market. The Solar Electric Power Association anticipates that there will be significant overlap between the PV system issues dealt with here and the issues facing interconnection of other distributed generation technologies. This Position Statement establishes a framework for identifying common issues.

The Solar Electric Power Association acknowledges the important work being done by stakeholders including the American Solar Energy Society, the Interstate Renewable Energy Council, the National Association of Regulatory Utility Commissioners, the North Carolina Solar Center, and the Distributed Power Coalition of America to call attention to these issues.

Members of the Solar Electric Power Association have developed significant insight in these areas and can be of assistance to other utilities. The Solar Electric Power Association extends an offer of its expertise in areas related to PV interconnection to other utilities with the goal of removing barriers to wider use of PV. The Solar Electric Power Association will also track progress in these areas, serving an important public education role.

The Solar Electric Power Association asks utilities to sign on to one or both of the companion documents that have been developed. By signing on to the Technical Aspects of PV Interconnection and the Contractual Aspects of PV Interconnection, utilities indicate their agreement with the recommendations presented.


Solar Electric Power Association Membership includes a broad spectrum of the PV electricity industry: more than 130 members that represent investor-owned utilities and their subsidiaries, public power systems, rural electric cooperatives, and the PV Industry (PV and component manufacturers, distributors, and system integrators). Solar Electric Power Association members account for nearly 50% of total U.S. electricity sales (1.5 Billion MWh in 1998) and have some 40 million customers. Stakeholder Members include 25 research organizations, educational institutions, and state and local organizations.


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The Solar Electric Power Association has advocated technically-sound specifications for PV systems since its inception. The Association has required stringent technical specifications of all PV projects (some 1,300 PV systems in total installed between 1996 and 2000) co-funded by its TEAM-UP partnership with the Department of Energy. In fact, the Association s Technical Performance Specifications developed for the program have become a nationally-recognized guideline. Recently, national standards-setting authorities, including the Underwriters Laboratories (UL) and the Institute of Electrical and /Electronics Engineers (IEEE), have developed new standards and procedures to ensure safe operation of grid-connected PV systems. Two key standards (IEEE 929-2000 and UL 1741, described below), were developed through an extensive, consensus-based process involving utilities, inverter manufacturers, national laboratories, and other stakeholders. In addition, the National Electrical Code (NEC) Article 690 covers important safety aspects related to PV system design. These standards address all legitimate technical concerns, such as safety and power quality, and thus clear the way for simplified interconnection on a technical level.

The approval of IEEE 929-2000, Recommended Practice for Utility Interface of Photovoltaic Systems by the IEEE Standards Board on 30 January 2000 is an important step for safe interconnection. IEEE 929-2000 is a standard to which PV interconnection hardware can be designed, removing a costly and inefficient situation where different utilities and jurisdictions require different and specialized hardware. Not only does IEEE 929-2000 simplify PV interconnection, it is also the first IEEE standard allowing interconnection of non-utility-owned generation equipment. The IEEE 929-2000 standard applies to the PV inverter, the device that converts the PV system s dc electricity into ac electricity compatible with the utility grid (inverters are more formally known as "static power converters").

IEEE 929-2000 includes very specific requirements for systems of up to 10 kW, but it is relevant to PV systems of all sizes. In fact, the IEEE 929-2000 standard makes three distinctions based on the size of PV systems:

The IEEE 929-2000 standard development process also had a parallel effort to develop procedures so that an independent laboratory, can test the safety features of a particular inverter type. The UL test procedure is UL 1741, Standard for Inverters, Converters and Controllers for Use in Independent Power Systems. In sum, inverters that pass UL 1741 tests are guaranteed to meet IEEE 929-2000; such inverters do not need additional protective equipment to prevent islanding or filters to maintain power quality. There are many brands of utility-interactive inverters produced today that are able to meet the exacting requirements of IEEE 929-2000.


    IEEE 929-2000: Safety

    Utilities and the PV community now have an approved interconnection standard that ensures the safe operation of a PV system connected to a utility grid. Safety  for the utility lineman, for the utility equipment, and for the customer  was the primary concern throughout the development of the interconnection standard. The IEEE 929-2000 standard includes tightly-defined specifications that require the PV system inverter to cease to energize the utility line for specific out-of-tolerance conditions such as voltage and frequency trip settings when values are outside of acceptable limits. These inverters also include sophisticated and reliable anti-islanding protocols that include active detection functions to ensure that the inverter does not deliver power to the utility system when utility power is cut off or disconnected from the inverter. Additionally, detection functions ensure that the inverter will cease to energize the utility line when an excess of dc current is present at the ac interface.


    IEEE 929-2000: Power Quality

    The quality of power provided by the PV system must meet specifications for voltage, flicker, frequency, and distortion. Out-of-bounds conditions for any of these variables require the inverter to cease to energize the utility line. Voltage and frequency set points for systems larger than 10 kW may be altered by the utility to accommodate system-specific needs.

  • It is also important to note the proper role of the National Fire Protection Association, which is responsible for the National Electrical Code (NEC). Interconnected PV systems should be installed in accordance with Article 690 of the National Electrical Code (NEC), and in compliance with local building and electrical codes. In addition, PV installations should be permitted and inspected by the appropriate local jurisdictional authority.



    IEEE 929-2000 offers recommended practices based on PV system size because the size of the PV system relative to the capability of the utility line it is connected to affects the impact of interconnecting a PV system.


    1. Systems under 10 kW:

    No additional protection equipment (such as relays or isolation transformers), testing, engineering reports, or other conditions beyond that specified by IEEE 929-2000, UL 1741, and NEC 690 should be required of grid-tied PV systems under 10 kW to address technical concerns.

    Manual external disconnects should not be required for PV systems under 10 kW. For UL-listed, non-islanding inverters, which already have external AC disconnects, an additional external AC disconnect is redundant.

    A utility may, with customer consent, arrange for periodic maintenance checks, although such maintenance checks are largely unnecessary for small-sized inverters.

    Utilities and regulators should be aware that the economics of systems in this size category are such that any non-standard requirements can have a significant impact on the economics of a PV system. This is another reason that Solar Electric Power Association recommends that utilities and regulators consider simply adopting the standards of nationally-recognized bodies, without modification for small-sized inverters.


    2. Systems between 10 kW and 500 kW:

    IEEE 929-2000 also provides guidelines for PV systems between 10 kW and 500 kW. Although IEEE 929-2000 does not directly address the full diversity of unique local grid conditions, utilities and regulators should find that three national standards  IEEE 929-2000, UL 1741, and NEC 690  can be used as the basis for interconnection procedures for PV systems between 10 kW and 500 kW. Utilities should carefully consider whether any deviations or extra requirements for systems between 10 kW and 500 kW are, in fact, technically necessary  again realizing that uniform and simplified technical interconnection procedures will benefit both the utility and the customer.

    Experience of Association Member utilities shows that in many cases, just the three national standards are sufficient for systems up to a range of 100 to 250 kW in size. Other utilities and regulators should consider this experience before requiring additional protection equipment, testing, engineering reports, or other conditions. As always, any additional requirements placed on interconnection should be based only on legitimate technical concerns.

    Utilities and regulators may also want to consider that the simplest requirements (for systems 10 kW and under) may also applicable up to 50 kW in size. Thus, utilities and regulators might also consider it unnecessary from a technical standpoint to add protection equipment (such as relays or isolation transformers), testing, engineering reports, or other conditions beyond that specified by IEEE 929-2000, UL 1741, and NEC 690 for grid-tied PV systems up to 50 kW. The reasoning is that a 50 kW PV system size matches well with the conventional residential electric supply of 240 volts at 200 amps service. (The 240 volts at 200 amps at unity power factor would equal 48 kW.) Utilities normally do not require special studies or equipment for this common load connection, and therefore the analogy is that the simple requirements should appropriately also apply to interconnection at this level. Of course, some adjustments, such as different setpoints, may be appropriate; such adjustments would not noticeably affect the goal of simplified interconnection.


    3. Systems larger than 500 kW:

    It is clear that the larger the PV system, the larger the potential impact it may have on a utility line. Utility interconnection procedures for these larger systems will undoubtedly use a mix of standardized and customized requirements.

    Utilities and regulators can use these three national standards  IEEE 929-2000, UL 1741, and NEC 690  as the basis for interconnection procedures for PV systems greater than 500 kW. Additional procedures and conditions should be used only as appropriate to address legitimate technical concerns.





    The interconnection agreement between the customer-generator and their utility needs to be as simple as possible. It is in the interest of both the customer and the utility that the paperwork involved in establishing an interconnection agreement be easily read, understood, and signed by non-attorneys and non-engineers. Simplified interconnection agreements are already being used by a number of utilities around the country and are as short as one page. (note: a sample contract is included at the end of this document)

    Some common issues are mentioned below. The list, which is not exhaustive, is intended to identify the kinds of contractual issues that can be viewed as overly-burdensome. In many cases, these issues are being worked out in state proceedings or other forums. Without going into specifics, the Solar Electric Power Association recommends that all utilities methodically simplify and streamline contractual aspects of interconnection.

    Issues of metering, rates, and tariffs go beyond the scope of this position statement  tied in with a much broader range of issues. In this companion document, the Association hopes to obtain consensus on a smaller set of contractual issues that will simplify interconnection and promote wider use of clean, renewable, and reliable solar power. The debates over metering, rates, and tariffs can then take place without having to involve issues that, in most cases, can be straightforwardly resolved.


    Insurance and indemnification.

    Any requirements for insurance and indemnification should be reasonable. It may not be necessary for customer-generators to be required to purchase additional liability insurance if the customer already has coverage of at least $100,000 (for residential systems) or $250,000 (for commercial systems). Moreover, utilities and regulators should be aware that it may be inappropriate to require customer-generators to indemnify their utility.


    Processing of interconnection agreements.

    Utilities and regulators should ensure a timely period (about ten working days) in which customers are notified that an interconnection agreement has been accepted once the agreement has been submitted by the customer-generator. If a utility wishes to inspect a system prior to its interconnection, it should do so within the same timely period after submittal of the agreement by the customer. The utility should notify the customer-generator of an upcoming inspection, so that the customer can have the system installer present, if needed.

    Utilities should designate and publicly announce a specific point of contact - an office or an individual employee - responsible for expediting connection requests and working with customers and PV system installers on interconnection issues. This would address the frequent complaint that their requests for interconnection have been ignored, delayed or passed off from one person to another, leading to lengthy delays before the customer receives an appropriate response. The Association offers to host and maintain this list of contacts on its publicly accessible Internet site.


    Access to customer premises.

    It should not be necessary for utilities to have greater access to a customer s property than it already has in order to inspect meters or utility lines. Once the interconnection agreement has been approved by the utility, if a utility wishes to inspect a system, it should have a reasonable cause, such as safety, and should have the consent of the customer.


    Conflict resolution.

    A neutral third party (in most cases the state utility commission or (for publicly-owned utilities) the utility board) should be established to provide a simple conflict resolution process to deal with issues that may arise regarding interconnection requirements between utilities and owners of small-scale, grid-connected PV systems.



    Utilities and regulators should be aware that even seemingly-modest fees can be "deal-killers," especially for small PV systems. Monthly charges (utilities have cited standby or metering as justifications) and other fees (such as inspection, etc.) are routinely cited as a deterrent to ownership of small systems. For example, a $5 monthly metering charge on a typical 2 kW PV system would consume 19% of the monthly energy savings.

    Although the Association makes no recommendations regarding fees or charges, comparison to how a utility assesses fees on an increase in load could be usefull, particularly for small PV systems. For example, utilities often do not charge a special fee if there is an increase in load (e.g., a second refrigerator, adding a central air conditioning unit)  in fact, they would be hard pressed to track such changes at an individual customer location. In all cases the utilities and regulators should strive to establish fees that are reasonable and justified.

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