Utility Interconnection and Metering Definitions

Utility Interconnection and Metering Definitions establish the standardized terminology and conceptual framework required for the integration of distributed energy resources—particularly residential solar power systems—with the electric utility grid. These definitions enable clear communication, regulatory compliance, contract formulation, and technical implementation between system owners, installers, and utility providers. The set covers all critical aspects of interconnection processes, metering configurations, operational permissions, and energy measurement points necessary to ensure safe, reliable, and transparent interaction between customer-owned generation and the utility grid.

Interconnection Application Definition

The Interconnection Application is a formal request submitted by a customer or system installer to the utility company to initiate the process of connecting a distributed generation system, such as a residential solar power system, to the utility grid. This application includes detailed technical information about the system, site location, equipment specifications, and intended operational parameters. It serves as the initial step for the utility to assess system compatibility, safety, and compliance with applicable standards before granting permission to connect.

Interconnection Agreement Definition

The Interconnection Agreement is a legally binding contract executed between the utility and the customer or system owner after successful review of the interconnection application. This agreement outlines the terms, conditions, responsibilities, and technical requirements governing the operation of the distributed energy resource in parallel with the utility grid. It includes provisions for system maintenance, safety protocols, liability, operational limits, and procedures for disconnection under fault or emergency conditions.

Permission to Operate Definition

Permission to Operate (PTO) is the formal authorization issued by the utility to the system owner, granting the right to energize and operate the interconnected distributed generation system. This permission is contingent upon satisfactory completion of all required inspections, testing, and compliance with interconnection standards. Obtaining PTO is mandatory before the system can export energy to the grid or be considered fully operational under interconnection terms.

Revenue Meter Definition

The Revenue Meter is the primary metering device installed at the point of interconnection that measures the amount of electrical energy exchanged between the customer’s premises and the utility grid for billing purposes. It records both energy consumption from the grid and energy supplied back to the grid by the distributed generation system, ensuring accurate financial transactions between the customer and utility. Revenue meters must meet utility and regulatory standards for accuracy, tamper resistance, and communication capabilities.

Production Meter Definition

The Production Meter is a dedicated meter that exclusively measures the gross electrical energy generated by the distributed generation system, independent of the customer’s energy consumption. It provides data on total system output, which is essential for performance monitoring, incentive programs, and verifying renewable energy production. The production meter’s readings support analyses of system efficiency and can be used to calculate credits or payments in net metering or feed-in tariff arrangements.

Metering Point Definition

The Metering Point is the physical location where the metering devices (such as revenue or production meters) are installed to measure electrical energy flows. This point defines the boundary between the utility’s electrical system and the customer’s system, serving as the reference for energy accounting, operational control, and safety protocols. Proper identification and configuration of the metering point are critical for ensuring accurate measurement and compliance with interconnection requirements.

Inadvertent Export Definition

Inadvertent Export refers to the unintentional flow of electrical energy from the customer’s distributed generation system to the utility grid during periods when export is not authorized or expected, such as when the system is operating in a mode designed to prevent export or during certain protective conditions. This phenomenon can occur due to timing mismatches between generation and load, control system behavior, or equipment malfunctions. Managing inadvertent exports is important to maintain grid stability and comply with interconnection agreements.

Utility Witness Test Definition

The Utility Witness Test is a procedural inspection and operational test conducted by utility personnel to verify that the interconnected distributed generation system meets all technical, safety, and operational requirements before granting Permission to Operate. This test typically includes verification of proper metering installation, functional protective equipment, system response to grid disturbances, and compliance with interconnection standards. The utility’s presence during testing ensures transparency and confirms that the system will not adversely affect grid reliability or safety.

This diagram illustrates the relationship between the Customer Premises with Distributed Generation, the Metering Point where Revenue and Production Meters are installed, and the Utility Grid governed by the Interconnection Agreement and Permission to Operate. The arrows indicate the flow of energy and information necessary for system integration.