Question

Question: Greetings basic question here for anyone familiar Enphase 208V micro inverters:I am looking at a data sheet for the Q8H-3P-72-E-US that says its a 1.83A source at 208V, it goes on to suggest 15 max per 20A circuit, do each of these micro inverters connect to all three phases (3-wire)?Or to they 'stagger' and each connect to a phase set (2-wire)?If they stagger it seems 1 the maximum number per 3-wire 208 20A circuit would be about 12.https://enphase.com/download/iq8-commercial-microinverters-data-sheet

Answer 1

You're asking about how Enphase IQ8H-3P microinverters are wired into a 208V 3-phase panel, specifically regarding phase balancing and circuit loading. Here's the breakdown

The IQ8H-3P microinverters DO NOT connect to all three phases. They connect to one phase pair.

Here's why and how it works: Phase Pairing

The Enphase IQ8H-3P is designed to connect to a single pair of phases in a 208V 3-phase system. This is the key. Think of it as a single-phase 208V connection between two of the three lines.

Staggering

To properly balance the load across all three phases, microinverters connected to the same circuit are staggered. This means that the microinverters are installed across all three phase pairs to distribute the generation.

Why the 15 Inverter Limit?

The data sheet suggestion for 15 microinverters per 20A circuit is based on the following calculations:

Maximum Inverter Current = 1.83 ANumber of Inverters per Branch Circuit = 20A  80% / 1.83 A ≈ 8.74Maximum Number of Inverters per Branch Circuit = 8

This is based on the 80% circuit capacity rule by the NEC:

20 A  .8 = 16A

Important Considerations and Calculations NEC (National Electrical Code)

The NEC's 80% rule limits continuous loads on a breaker to 80% of the breaker's rating. This is crucial for safety.

Enphase's Documentation

Always prioritize Enphase's official documentation and design tools. They provide specific guidance for your chosen microinverter, the region, and any relevant local codes.

Practical Example

Let's say you have a 3-phase panel with phases A, B, and C. You'd wire the microinverters on a single 20A breaker to the following phase pairs: Inverters 1-5: A-B Inverters 6-10: B-C Inverters 11-15: C-AThis distributes the load across all three phases.

In Summary:

The Enphase IQ8H-3P microinverters connect to one* phase pair (2-wire) within a 208V 3-phase system. They are staggered across all phase pairs to balance the load. Following Enphase's guidelines and NEC regulations is crucial for safety and optimal system performance. Flag for review

Answer 2

You're asking about how Enphase IQ8H-3P microinverters are wired into a 208V 3-phase panel, specifically regarding phase balancing and circuit loading. Here's the breakdown

The IQ8H-3P microinverters DO NOT connect to all three phases. They connect to one phase pair.

Here's why and how it works: Phase Pairing

The Enphase IQ8H-3P is designed to connect to a single pair of phases in a 208V 3-phase system. This is the key. Think of it as a single-phase 208V connection between two of the three lines.

Staggering

To properly balance the load across all three phases, microinverters connected to the same circuit are staggered. This means that the microinverters are installed across all three phase pairs to distribute the generation.

Why the 15 Inverter Limit?

The data sheet suggestion for 15 microinverters per 20A circuit is based on the following calculations:

Topic: Enphase 208V micro inverters, max per 20A circuit?