Enphase IQ Combiner PCS and PV backfeed breaker ampacity question

[jaggedben]

Actually to be clear, I don't know if that functionality would allow greater than 40A to the main panel via the method you suggest. It might be limiting to 40A as I discussed. By Q1 2024 they are supposed to have expanded functionality but I'm still not 100% clear on the details.

 

[Designer101]

Not sure what this particular PCS is capable of, but you don't think that 705.13 et al would permit a PCS to monitor both the grid contribution to the 125A bus (via the CTs labeled "Consumption" in the OP diagram) and the inverter contribution to the 125A bus (from both PV and ESS), and impose only the joint limit that the sum is no more than 120% * 125A / 125% = 120A? Rather than rigidly limiting the total inverter output to 40A, regardless of the grid draw?

Cheers, Wayne

lets take example of powerwall 2 and powerwall plus. one approach by tesla... they have said max pcs setting is 200A. Means controllable solar(if used tesla powerwall plus), controllable storage Powerwall2 and any third part sources and inveretrs still has to follow 120 percer rule.
I have not found such docuementation for enpahse but enpahse should be able to do the same?

 

[wwhitney]

lets take example of powerwall 2 and powerwall plus. one approach by tesla... they have said max pcs setting is 200A. Means controllable solar(if used tesla powerwall plus), controllable storage Powerwall2 and any third part sources and inveretrs still has to follow 120 percer rule.

That's not quite how I would put it--it means when applying the 120% rule, you can ignore the PCS controlled sources, so only the uncontrolled inverters and the utility-side main breaker need to be considered.

Cheers, Wayne

 

[solarken]

Without knowing the model of enphase storage, but based on the dwg notes, assuming this is 2ea Encharge 10's, the continuous current rating of each is 16A. So the max CC of the PV is 30.2A, and the max CC of the battery is 2*16=32A. The combined PV and battery is 30.2A + 2*16A = 62.2A, but if you can limit the combined output to 40A through a PCS function in the enphase envoy, why not put a 50A backfed breaker in the loadcenter to make sure the 120% bus rule is not violated?

 

[wwhitney]

The combined PV and battery is 30.2A + 2*16A = 62.2A, but if you can limit the combined output to 40A through a PCS function in the enphase envoy, why not put a 50A backfed breaker in the loadcenter to make sure the 120% bus rule is not violated?

Because the layout in the OP, if allowed per a PCS that monitors all current flowing to the service panel bus, allows the full use of the PV and ESS to offset load current when desirable? While your proposed configuration would require drawing grid electricity whenever the loads exceed 40A.

Cheers, Wayne