Idaho Power - Interconnection Guidelines

November 01, 2006

Summary

Idaho has not established uniform interconnection rules and procedures for net-metered systems or for large distributed-generation (DG) systems. However, through their respective net-metering tariffs, each of the state's three investor-owned utilities -- Avista Utilities, Idaho Power and Rocky Mountain Power -- has established outlines for the interconnection of small renewable-energy systems. Idaho Power's interconnection guidelines cover net-metered systems up to 100 kilowatts (kw) and larger DG systems. Idaho Power's rules are broken down by system capacity, and include provisions for systems under 25 kW; systems between 25 kW and 100 kW; systems between 100 kW and 1 megawatt (MW), and systems larger than 1 MW. The rules are intended to be simple for systems under 100 kW -- particularly for net-metered systems under 25 kW. Idaho Power's interconnection guidelines include these provisions:

• Dedicated transformers could be required (but likely will not be required for systems under 100 kW).
• A manual, lockable disconnect switch is required for all systems.
• All electrical specifications, such as voltage ranges, harmonics and power factor, are based on current UL, IEEE and NEC standards.
• Control relays are required for systems with an inverter that doesn't comply with IEEE 1547.
• Acceptance testing is not required for UL-listed inverters.
• Systems under 25 kW must be inspected once every three years if the project uses interconnection equipment that meets nationally recognized standards and if the system is approved by Idaho Power in advance. All other projects must be inspected annually.
• The owners of systems that are not net-metered must pay the Idaho Power a monthly operation and maintenance charge.

Idaho Power's interconnection web site, shown above, inlcudes applications and tariffs for net metering, and a four-step process for generators less up to 20 MW, and documents relevant to interconnecting systems exceeding 20 MW.