Utility-Interconnected Photovoltaic Systems: Evaluating the Rationale for the Utility-Accessible External Disconnect Switch (original) (raw)
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Photovoltaic Power Systems and the National Electrical Code: Suggested Practices
This suggested practices manual examines the requirements of the National Electrical Code (NEC) as they apply to photovoltaic (PV) power systems. The design requirements for the balance of systems components in a PV system are addressed, including conductor selection and sizing, overcurrent protection ratings and location, and disconnect ratings and location. PV array, battery, charge controller, and inverter sizing and selection are not covered, as these items are the responsibility of the system designer, and they in turn determine the items in this manual. Stand-alone, hybrid, and utility-interactive PV systems are all covered. References are made to applicable sections of the NEC.
Solar Energy, 2024
Solar photovoltaic (PV) costs have dropped rapidly making PV the fastest growing and least expensive electricity source. Grid-tied PV systems owned by prosumers currently dominate the market primarily due to historical net metering. As utility rate structures shift away from net metering, increase unavoidable costs or restrict grid access, solar prosumers have an increasingly economic path to grid defection. These trends coupled with increasing grid electricity costs and decreases in both PV and battery costs, have made economic grid defection and utility death spirals salient issues. To evaluate the economics and realistic potential of grid defection, this study evaluates eighteen case studies across the U.S. to assess the profitability of grid defection across different irradiation zones using hybrid PV-diesel generator-battery systems. The results show that grid defection is already economically advantageous in some solar-rich locations that have high electric rates. Rate structures and policy, however, can be used to encourage solar-prosumers to remain on the grid rather than grid defect. Utilities that have rate structures that discourage on-grid PV systems, however, may unintentionally incentivize grid defection. If consumers feel that inflation will be high for a long period of time they may use off-grid PV systems as economic hedges. Overall, the results of this study and the clear trends in economic and technical development indicate that regulators must consider mass economic grid defection of PV-diesel generator-battery systems as a near-term possibility and design rate structures to encourage solar producers to remain on the grid to prevent utility death spirals.
Progress in Photovoltaics: Research and Applications, 2012
The installed capacity of photovoltaic (PV) systems has recently increased at a much faster rate than the development of grid codes to effectively and efficiently manage high penetrations of PV within the distribution system. In a number of countries, PV penetrations in some regions are now raising growing concerns regarding integration. Management strategies vary considerably by country-some still have an approach that PV systems should behave as passive as possible, whereas others demand an active participation in grid control. This variety of grid codes also causes challenges in learning from "best practice." This paper provides a review of current grid codes in some countries with high PV penetrations. In addition, the paper presents a number of country-specific case studies on different approaches for improved integration of PV systems in the distribution grid. In particular, we consider integration approaches using active and reactive power control that can reduce or defer expensive grid reinforcement while supporting higher PV penetrations.
Regulatory Considerations Associated with the Expanded Adoption of Distributed Solar
2013
Consumer interest in and deployment of solar photovoltaics (PV) has accelerated in recent years. Increased adoption of distributed generation, particularly distributed solar PV, is expected to have impacts on utility-customer interactions, utility system cost recovery, and utility revenue streams. As a greater number of electricity customers choose to generate their own power, demand for utility system power declines. As a result, fixed system costs, such as the costs of transmission and distribution services, will be recovered over fewer kilowatt-hour (kWh) sales by the utility, and this could put upward pressure on electricity rates. Regulators are facing the challenge of defining and preparing for the potential rate and revenue impacts from expansion of distributed PV. Looking forward, it will be important to address potential financial impacts on utilities that are responsible for ensuring that the electricity infrastructure supports reliable electric service for customers. The regulatory context and rate structures governing utilities and owners of residential and commercial-scale distributed PV present both market opportunities and market barriers that will influence the path forward for the incorporation of higher penetrations of distributed PV. A number of regulatory models and rate design alternatives are available to address the challenges posed by the transition toward increased adoption of distributed PV. This paper is intended to help regulators: • Understand the sources of costs and benefits from increased adoption of distributed PV • Understand how regulatory models indicate different roles and value propositions for consumers, utilities, and non-utility electricity service providers • Understand how rate design alternatives affect the value proposition for PV adopters, non-adopters, and utilities • Frame the discussion with utilities, non-utility participants, and customers as they formulate equitable regulatory and rate design solutions. Costs and Benefits Distributed PV benefits system owners, utilities, the power system, and society in a variety of ways, including through the provision of energy and capacity, transmission and distribution system deferrals, line loss savings, fuel cost hedging, and environmental and health benefits. The costs include those associated with equipment, operations and maintenance (O&M), program administration, interconnection, and integration of the distributed systems. The magnitude of the costs and benefits of distributed PV vary according to the level of penetration, the local grid characteristics, and the coincidence of the solar electric production with the peak demand in the region. Assessments of costs and benefits have varied widely, and in some cases there is a lack of consensus regarding appropriate methodologies for assessing them. Understanding the costs and benefits of distributed PV is essential to creating appropriate rate structures. The benefits and costs of distributed resources play into the consideration of ratepayer equity and rate design, especially at increased levels of adoption.
Photovoltaics for demand-side management utility markets: a utility/customer partnership approach
World Conference on Photovoltaic Energy Conversion, 1994
Photovoltaic (PV) power systems located at customer sites can be used to meet electric utility needs for demand-side management (DSM) applications. PV-DSM can also represent a high-value intermediate market for PV power in the utility sector. Maximum value for PV in DSM applications can be achieved by incorporating a dispatching capability to PV power systems (through the addition of storage).
IEEE Industry Applications Magazine
Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults by means of islanding detection. However, in case of a wide-scale penetration of single-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for single-phase PV power systems under grid faults along with reactive power injection is studied in this paper. Three reactive power injection strategies are discussed in detail. Simulation...
The capacity of photovoltaic systems connected to the distribution system (distributed photovoltaic systems [DPV]) has increased consistently over the past 8 years in the United States, with continued growth anticipated globally. Because the power system was originally designed for one way power flow from centralized generators to distributed loads, this increasing deployment of DPV can impact operations at the distribution level and, for higher penetrations, at the transmission level. When these issues occur, upgrades are required to mitigate them and maintain voltage, reliability, and power quality, incurring a cost; we refer to these costs as distribution upgrade costs. While today these costs are typically analyzed reactively as individual DPV systems apply for interconnection to the grid, it is important to develop and implement forward-looking approaches for calculating distribution upgrade costs that can be used to inform system planning, market and tariff design, cost allocation, and other policymaking as penetration levels of DPV increase.
Market Assessment of Residential Grid-Tied PV Systems in Colorado
2000
PV panel installation on private residence in Gardner, Massachusetts Standard equipment for a household PV system. For example, this is the equipment for the PV installation at the Governor's mansion: (1 and 2) inverter, and (3) service disconnect switch. The equipment was installed near the existing household breaker box (4).
Public Response to Residential Grid-Tied PV Systems in Colorado: A Qualitative Market Assessment
1998
Writer Dawn Griffin assisted in project management and conducted some of the focused interviews and prepared field notes. Karen Brown, Ph.D., helped in the development of the qualitative codebook. Aiding considerably in the coding of the qualitative data were Elisabeth Sheff and Dorian Wilson, doctoral candidates in the Department of Sociology, University of Colorado, Boulder. Rochelle Watters provided support in a variety of ways, including preparation of the manuscript. Jim Miller, Kay Vernon, and David Crawford provided graphics, word processing, and editorial support.