Is conduit required inside attic when microinverters are used?

[WhittakerJ]

I'm installing a diy system. I'm using Enphase microinverters and running 3 strings back to my main. I'm curious if I can just penetrate the attic rather than wrap the house in conduit? If so do I need conduit in the attic? Or should I convert to Romex? Or just leave the cables as is and pop out near the main back into new conduit?

[Ampster]

Local codes may differ but I transitioned from the Enphase cable to Romex in a junction box. I don't think of Enphase branch circuits as strings. What size are your branch circuits? Are you using an Envoy?

[WhittakerJ]

There are 3 strings each are 4,225 each. Yea I was going to run them into a combiner 3 near my main.

[Ampster]

There are 3 strings each are 4,225 each. Yea I was going to run them into a combiner 3 near my main.

I presume that is Watts of DC capacity. Wire size should be based on AC current plus an upsize if the distance is long.

[WhittakerJ]

I presume that is Watts of DC capacity. Wire size should be based on AC current plus an upsize if the distance is long.

Yea, sorry, that's the DC rated size of the system divide by 3 for each string.

[Ampster]

Are there an equal number of micros on each branch? I think Enphase recomends a max number based on inverter and wire size of branch cable.

[WhittakerJ]

Yea, I've got 39 panels on IQ 7 Micros. 13 on each circuit.

branch circuit.jpg

[Ampster]

That was helpful. The advantage of combining them might be that you could get by with a 50 Amp breaker at the panel which might help the calculations on the panel bus bar. You would have to calculate the max current for each micro and add them up, but it could be worth it, if it means not derating your panel. I am still not clear if you are using the Enphase combiner with an integrated Envoy? The advantage of the Envoy is that you will get data on each micro and the combiner gives you the ability to isolates branch circuits (strings) for diagnosis.
My attic run was over 60 ft. so I used 10 AWG, because I had it around and I did not want to worry about voltage drop. I still used a 20 Amp breaker.

[WhittakerJ]

Yea I'm using the combiner box with the integrated envoy. I have to derate the main to 175 to support the bus. I'm going to switch to Romex and go through the attic.

[Alexandremuller]

Hi guys

You can use a flexible metal conduit inside the attic and # awg 10 . To transition between attic and attic I used soladeck

[Ampster]

Hi guys

You can use a flexible metal conduit inside the attic and # awg 10 . To transition between attic and attic I used soladeck

Yes you can, but in my jurisdiction in California metal conduit is only required for DC. For my micros, as noted above, I used 10 AWG Romex in the attic. Apparently that is what the OP has concluded as well.