690.2 PV Definitions. Multimode Inverter.

A Multimode Inverter has the capabilities of both the utility-interactive inverter and the stand-alone inverter. This particular inverter comes with a receptacle that will remain energized during a power outage as long as the sun is shining on the PV modules.
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A Multimode Inverter has the capabilities of both the utility-interactive inverter and the stand-alone inverter. This particular inverter comes with a receptacle that will remain energized during a power outage as long as the sun is shining on the PV modules.

Code Change Summary: A new definition of a Multimode Inverter was added to 690.2.

A Multimode Inverter has the capabilities of both the utility-interactive inverter and the stand-alone inverter.

There are generally two types of PV systems, a stand-alone PV system that has no interconnection to the utility grid and a utility interactive system that can backfeed excess power into the utility lines. The NEC® has specific requirements for both types of PV systems.

In a utility interactive system, when utility power is not present, the PV inverter senses a power loss and stops backfeeding the grid with excess power. This ensures safety for the utility lineman who is trying to repair power lines that are supposed to be de-energized. This PV inverter feature is called anti-islanding.

Multimode Inverters can provide the same anti-islanding feature when utility power is off while leaving the homeowner with an energized convenience receptacle during a power outage. The energized receptacle is powered completely by the PV system, similar to a stand-alone PV system.

Below is a preview of the NEC®.  See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on the “free access” tab and select the applicable year of NFPA 70 (National Electrical code).

2014 Code Language:

690.2 Multimode Inverter. Equipment having the capabilities of both the utility-interactive inverter and the stand-alone inverter.

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690.2 PV Definitions. Multimode Inverter.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is a Multimode Inverter?

A: Equipment capable of only utility-interactive operation.
B: Equipment with capabilities of both the utility-interactive inverter and the stand-alone inverter.
C: Equipment capable of only stand-alone operation.
D: All microinverters.
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