Installation and Interconnection

James M. Daley and Anne-Marie Borbely


12.1 The Cost of Ignorance

12.2 Codes and Standards

12.2.1 Standards

12.2.2 Model Codes

12.3 Installation of a DG Unit

12.4 Operation

12.4.1 Notes on Figure 12.2

12.5 Interconnection

12.5.1 Power Sources

12.5.2 Perspectives

12.5.3 System Faults

12.5.4 DG Considerations

12.5.5 Protective Relaying Descriptions of the Devices

12.5.6 Perspective

12.5.7 Power Source Control

12.5.8 Time Constants

12.5.9 Power System Design Islanded Operation Closed Transition Transfer Extended Parallel Operation 12.5.10Permissive Relaying 12.5.11Protective Relaying

12.6 Summary References

Installing new electricity-producing equipment near, on, or within buildings requires the same permit evaluation process as any other modification to the site, with one telling exception: the existing code structure was never designed for wide-scale deployment of electric generators outside the ownership and control of electric utilities.

As of the year 2000, the competitive position leveled somewhat for both utility and nonutility owned generation units. Any equipment not located on utility property and used expressly for the operation of that utility became subject to the same local code requirements as all other owner-operators. Therefore, utilities attempting to enter the DG marketplace by installing generators at customers' sites will undergo the same permitting process as energy service companies, local distributors, manufacturers, or the energy customer.

The essential roadblock still exists, however, for all new DG technologies, regardless of ownership. The sourcebooks for local code officials — the National Electrical Code, the International Fuel Gas, Plumbing, Mechanical, Building, and Fire Codes, and the National Life-Safety Code — contain no reference for microturbines, Stirling engines, or, until recently, fuel cells.

Although standards exist for the installation of traditional on-site generators, their interpretation — and the building codes they must interact with — vary between state and local jurisdictions. For this reason, this section merely presents the suite of issues that may be encountered; it is not a definitive guide to the codes or standards.

12.1 The Cost of Ignorance

Figure 12.1 shows the cost to a developer for failing to adequately account for code requirements in his product development. By year 8, the product in code compliance is no longer generating sunk costs, and by year 15 it has returned all previous investment. In contrast, the product out of compliance fails to establish a revenue stream, and by year 16 the cost of investment capital is beyond recovery. As shown in later sections, it can take three years to develop a new consensus standard and another two years to have it referenced in the model codes. For entirely new technologies that may impact life safety issues and building construction, a new standard must be initiated five years prior to their commercial introduction, or manufacturers will continue to sink capital into businesses physically incapable of generating substantial revenue.

Absent any explicit definition of what comprises safe installation and operation, each building code official in the 44,000 state and local code authorities across the United States must independently determine the appropriate requirements one site at a time. Each unit will be evaluated under an "alternative methods and materials" clause that does not imply approval. A code official can require any number of design, test, and documentation reviews

500 0


Annualized Sunk Investment & Revenue d Without Code Acceptance ■ With Code Acceptance |


Revenue comparison of code-compliant versus non-compliant technology.

before ruling on the installation. In many cases, this may result in the unit being denied permission to operate, and there is no appellate process to fall back upon.

12.2 Codes and Standards

Standards are documents that outline the agreed-upon design and performance of a given technology, while model codes address the design, installation, and operation of materials and equipment as it relates to public health and life safety. Although standards are not automatically accepted into model codes, thousands of standards are referenced as required practice for a given installation. For example, the National Electrical Code references NFPA 110, Standard for Emergency and Standby Power Systems, for buildings required to have on-site power in the event of a grid failure. A key difference between model codes and standards is that standards, and any modifications to them, are approved through a vote that involves any and all interested parties, while model code modifications are voted on solely by code officials.

12.2.1 Standards

Several types of standards have been developed for industry, but the two most relevant to DG technologies are (1) product testing standards that outline the criteria for safe operation, and (2) rating standards, which define

testing and reporting procedures to compare performance between manufacturers. Individual standards relevant to DG products will be discussed below. Most industry standards are consensus based, a codified process that allows manufacturers, regulatory officials, suppliers, and other interested parties to participate in a procedure open to the public. The process can take three to five years to complete, depending upon the complexity of the standard, the presence or absence of related standards, and the number of competitive products under development.

Some organizations, such as UL, will write a "bench" standard that can be used as an interim approval for a new product (typically during prototyping) and may be used for third-party approval until a formal standard is adopted. This is not a recommended practice for long-term, widespread adoption of a new technology by local code officials, however. For an accepted pathway to the market, all interested parties must develop a standard through an accredited organization and support its adoption into the model codes.

Solar Stirling Engine Basics Explained

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The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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