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

[tortuga]

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

 

[wwhitney]

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)?

They stagger.

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

How's that? 5 (number of balanced sets) * 1.83A (current from each conductor) * sqrt(3) (how currents from A-C and A-B add on line conductor A) = 15.84A. Just less than the 16A allowable continuous current on a 20A circuit.

Cheers, Wayne

 

[tortuga]

Hmm perhaps I am looking at it wrong would it not appear as a delta source?
Like this

Inverter​	Line​
​	A​	B​	C​
1​	1.83​	1.83​	​
2​	​	1.83​	1.83​
3​	1.83​	​	1.83​

 

[wwhitney]

That's correct, but for example on Line A, given the phase angle between the current from inverter 1 and from inverter 3, the total current is 1.83*sqrt(3), not 1.83*2. Same for Lines B and C.

This applies whenever you distribute identical 208V 2-wire sources/loads in a balanced fashion around a delta. It's the reason that one uses a VA method for determining panel loads, for example (which is non-conservative if the 208V sources/loads are not fully balanced).

Cheers, Wayne

 

[tortuga]

That's correct, but for example on Line A, given the phase angle between the current from inverter 1 and from inverter 3, the total current is 1.83*sqrt(3), not 1.83*2. Same for Lines B and C.

This applies whenever you distribute identical 208V 2-wire sources/loads in a balanced fashion around a delta. It's the reason that one uses a VA method for determining panel loads, for example (which is non-conservative if the 208V sources/loads are not fully balanced).

Cheers, Wayne

Oh right thanks Wayne.