PowerPoint ® Presentation Chapter 12 Utility Interconnection Distributed Generation Generators Inverters Interconnection Codes and Standards Interconnection Concerns Point of Connection Metering Utility Interconnection Policies Public Utilities Regulatory Policy Act (PURPA) Interconnection Agreements

Chapter 12 — Utility Interconnection With distributed generation, utility customers are served by both the centralized power plants and the power exported from interconnected distributed generators.

Chapter 12 — Utility Interconnection Most power is generated by rotating generators, which require precise interconnection procedures to avoid damage to the equipment and the utility.

Chapter 12 — Utility Interconnection Inverters must be identified as interactive and listed to required standards before being interconnected.

Chapter 12 — Utility Interconnection Utility-interactive systems are the simplest way to interconnect a PV system with the utility.

Chapter 12 — Utility Interconnection The inverters in multimode systems can continue to supply power to certain loads in the event of a utility outage.

Chapter 12 — Utility Interconnection Several codes and standards address specific interconnection issues with PV systems.

Chapter 12 — Utility Interconnection During a utility outage, an islanding inverter can energize the utility lines around the PV system, potentially damaging equipment and creating a serious safety hazard.

Chapter 12 — Utility Interconnection When a single-phase inverter is added to a system with more than one ungrounded (hot) conductor, the neutral conductor can become overloaded.

Chapter 12 — Utility Interconnection Adding single-phase output from an interactive inverter to a three-phase power system can result in unbalanced voltages between the phases.

Chapter 12 — Utility Interconnection Interactive inverters can be connected to either the load side or the supply side of the main service disconnect.

Chapter 12 — Utility Interconnection Interconnection on the load side of the service disconnect is done through back-fed circuit breakers.

Chapter 12 — Utility Interconnection Back-fed circuit breakers are circuit breakers on the load side of the main service disconnect that supply PV power to the busbar.

Chapter 12 — Utility Interconnection Interconnection on the supply side of the service disconnect must include a separate service-rated fused disconnect or circuit breaker.

Chapter 12 — Utility Interconnection Interconnected PV systems must include labeling that clearly identifies the disconnects and point of interconnection.

Chapter 12 — Utility Interconnection With a net metering arrangement, exported power makes the electric meter run backward, crediting the PV system owner for power supplied to the utility grid at the retail rate.

Chapter 12 — Utility Interconnection Dual metering can be accomplished with two separate meters or with one meter that can measure and record energy flow in both directions separately

Chapter 12 — Utility Interconnection PURPA defines the entities that can contribute to the collective energy supply.

Chapter 12 — Utility Interconnection Some utility interconnection agreements require outside disconnects for PV systems so that the system can be isolated in the event of an outage or emergency.

Chapter 12 — Utility Interconnection Net metering policies vary by state and sometimes also by utility.