Enphase IQ series +7 inverter

hhsting

Senior Member
We are still in NEC 2014.

Attached sketch shows AC main service disconnect line side 208V three phase gets tapped to solar AC sub panel 208V three phase which has 200A main circuit breaker. The solar AC sub panel has feeder breakers which feed Enphase Q +7 aggregator which then feeds 3 Enphase IQ Series +7 microinverters. DC side of microinverter feeds solar panel.

Solar sub panel, Aggregator, IQ +7 invertor are on roof. Main service disconnect AC is inside building electric room. Their is an EGC running from solar sub panel to Aggregator, invertor then to solar panel.

The main service disconnect has system ground and from their EGC is fed to the AC solar sub panel and their is another grounding electrode in the solar AC sub panel.

My questions are following for those of you who are code expert and has experience in IQ series inverter:

1. According manufacturer Enphase IQ +7 inverters have integrated grounding and double insulation. DC circuit is isolated and insulated from ground. As a result the EGC or GEC is not required. Since EGC or GEC is not required, what methods of bonding metal parts is used from inverter to the solar panel, rack or is this not required for IQ +7?

2. Inverter is on roof so is aggregator which has fuse. If I provide single disconnecting means at aggregator per NEC 2014 Article 690.17 then would I still need to comply per NEC 2014 Article 690.15(A)(B)(C)?

3. Do I need to comply per NEC 2014 Article 690.16?

4. Solar sub panel is on roof remote from main service disconnecting means which is inside building electric room. Do I need to comply per NEC 2014 Article 690.13(A)(E)? Their is exception for 690.13(A) but not for 690.13(E) is confusing.

5. Any one know ENphase IQ +7 inverter is on roof how does it comply per rapid shutdown Nec 2014 Article 690.12? How does one initate rapid shutdown?

6. Grounding as it relates to main service disconnect and sub panel shown attached sketch is it ok code compliant?

Please ignore my ignorance I am not trying to troll here. I really appreciate all your input and consider them really helpful.


Thank you in advance.


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jaggedben

Senior Member
1: No bonding of the inverter is required. Solar panels and racking still (almost always) require bonding. Industry standard these days is for most racking mechanical connections to also be listed for bonding (UL 2703), requiring a minimal number of wire connections from circuit j-boxes to the racking (e.g. one per row of panels, or even per array). Look at racking datasheets or manuals, this is usually not detailed on plans. It has nothing to do with the inverters per se.

2: With Enphase usually the cable connector plugs, which are load break rated, are considered to fulfill compliance on the roof for all that stuff. I honestly haven't discussed this with any AHJs since the IQ system came online, but that's how it's been recognized for all the two dozen or so AHJs I work in for a few years now. With the subpanel on the roof you also have that disconnecting means (circuit breaker) within sight, presumably (but see point 4).

3: No, 690.16 is only relevant for DC circuits, which contain no fuses in an Enphase system. Inverter output circuits are not 'PV source circuits' or 'PV output circuits', check the definitions at the beginning of 690. The aggregator fuses are only energized from one side (utility).

4: It does not seem right to me that you have a supply-side connection going directly to a subpanel on the roof. See 705.22 and 705.31 (note 10ft limit). Industry standard would have the subpanel on the ground near the service tap, or a fused disco on the ground feeding the subpanel on the roof.

5: No special equipment is needed for rapid shutdown with micro-inverter systems, since a utility-side shutdown brings about compliance. Simply put a 'Rapid Shutdown Switch' label on the main AC disconnecting means for the solar system and you're done.

6: Controversial. Treat it as an additional service disconnect, or don't, and then make sure the AHJ agrees and be consistent with code. See past threads. 2020 NEC will finally clarify this (but I'm not happy about how it does so).
 

hhsting

Senior Member
1: No bonding of the inverter is required. Solar panels and racking still (almost always) require bonding. Industry standard these days is for most racking mechanical connections to also be listed for bonding (UL 2703), requiring a minimal number of wire connections from circuit j-boxes to the racking (e.g. one per row of panels, or even per array). Look at racking datasheets or manuals, this is usually not detailed on plans. It has nothing to do with the inverters per se.

2: With Enphase usually the cable connector plugs, which are load break rated, are considered to fulfill compliance on the roof for all that stuff. I honestly haven't discussed this with any AHJs since the IQ system came online, but that's how it's been recognized for all the two dozen or so AHJs I work in for a few years now. With the subpanel on the roof you also have that disconnecting means (circuit breaker) within sight, presumably (but see point 4).

3: No, 690.16 is only relevant for DC circuits, which contain no fuses in an Enphase system. Inverter output circuits are not 'PV source circuits' or 'PV output circuits', check the definitions at the beginning of 690. The aggregator fuses are only energized from one side (utility).

4: It does not seem right to me that you have a supply-side connection going directly to a subpanel on the roof. See 705.22 and 705.31 (note 10ft limit). Industry standard would have the subpanel on the ground near the service tap, or a fused disco on the ground feeding the subpanel on the roof.

5: No special equipment is needed for rapid shutdown with micro-inverter systems, since a utility-side shutdown brings about compliance. Simply put a 'Rapid Shutdown Switch' label on the main AC disconnecting means for the solar system and you're done.

6: Controversial. Treat it as an additional service disconnect, or don't, and then make sure the AHJ agrees and be consistent with code. See past threads. 2020 NEC will finally clarify this (but I'm not happy about how it does so).
All breakers except one in AC solar sub panel are back feeding to grid. How does one size the AC solar sub panel?

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hhsting

Senior Member
Probably for the sum of breakers in it, per 705.12(D)(2)(3)(c)
Attached is sketch of AC solar subpanel 208V, three phase, 200A main circuit breaker with 200A bus. L1, L2, L3 are legs of the bus.

All the 2 poles sub breakers except the 20A go to single phase 208V single phase Enphase Aggregator.

The 20A 2 poles sub breaker go to Envoy Communication device which is a load.

Am I doing the calculation correct per 705.12(D)(2)(3)(c)? If yes then maximum breaker needed and bus size is 300A? If not then what is the correct calculation per 705.12(D)(2)(3)(c) to size sub panel?


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hhsting

Senior Member
It appears you are calculating it correctly and a 200A panel is not adequate for this installation.
Should not nec 2014 Article 705.12(D)(2)(3)(c) apply to load side of side of service disconnecting means? What I have is point of interconnection from supply side of service disconnecting means to the sub panel. Does NEC 2014 Article 705.12(D)(2)(3)(c) apply in my case?

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hhsting

Senior Member
Should not nec 2014 Article 705.12(D)(2)(3)(c) apply to load side of side of service disconnecting means? What I have is point of interconnection from supply side of service disconnecting means to the sub panel. Does NEC 2014 Article 705.12(D)(2)(3)(c) apply in my case?

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ggunn

PE (Electrical), NABCEP certified
Should not nec 2014 Article 705.12(D)(2)(3)(c) apply to load side of side of service disconnecting means? What I have is point of interconnection from supply side of service disconnecting means to the sub panel. Does NEC 2014 Article 705.12(D)(2)(3)(c) apply in my case?

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705.12(D) only applies to load side connections, that's correct, but since you are interconnecting on the supply side of the main service disconnect your panel is not a sub panel. Every breaker in it is a service disconnect unless you have OCPD between it and the service conductors, but then it would be load side interconnected and 705.12(D) would apply.
 

hhsting

Senior Member
705.12(D) only applies to load side connections, that's correct, but since you are interconnecting on the supply side of the main service disconnect your panel is not a sub panel. Every breaker in it is a service disconnect unless you have OCPD between it and the service conductors, but then it would be load side interconnected and 705.12(D) would apply.
Dont follow. So post #1 sketch which has 200A main curcuit breaker solar ac panel 705.12(D) would not apply however should I add disconnect between AC solar panel and supply side connection then 705.12(D) would apply?

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hhsting

Senior Member
This may be yet another gray area and controversy what is load side and what is line side in post #1 for solar side.
 
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ggunn

PE (Electrical), NABCEP certified
Dont follow. So post #1 sketch which has 200A main curcuit breaker solar ac panel 705.12(D) would not apply however should I add disconnect between AC solar panel and supply side connection then 705.12(D) would apply?

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Sorry, I missed that your panel has a main breaker, but that IMO makes the rest of the panel load side connected. To qualify under (c) all the breakers in the panel connected to each busbar, discounting the main breaker, must total to less than the rating of the busbar.
 

hhsting

Senior Member
I always thought 705.12(D) load side meant load side of main building service disconnecting means. I must say I am superised that load side can also mean load side of AC PV system solar disconnect one right after supply side tap.

Which one of the above 705.12(D) means as load side main building service disconnect or AC PV system solar disconnect?

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ggunn

PE (Electrical), NABCEP certified
I always thought 705.12(D) load side meant load side of main building service disconnecting means. I must say I am superised that load side can also mean load side of AC PV system solar disconnect one right after supply side tap.

Which one of the above 705.12(D) means as load side main building service disconnect or AC PV system solar disconnect?

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Anything that has OCPD between it and the service (unprotected) conductors is on the load side of that OCPD.

A common configuration for us is a MLO AC aggregation panel feeding a fused disco connected to the supply (line) side of the building disco. The interconnection is supply side but the agg panel must conform to 705.12(D) because it is on the load side of the fused disco. Substituting a panel main breaker for the fused disco doesn't change anything.
 

jaggedben

Senior Member
Even if the load side rule does not apply (and I think it does), 200A is probably still not enough for 240A of backfeed on one phase under the rules for inverter outputs. (125% of nameplate). The only 'out' I see here is if all the aggregator breakers are oversized.
 

hhsting

Senior Member
Ok 705.12(D) does not apply. Aside from load side or not following is necessary for apply:


"...where distribution equipment including switchgear, switchboards or panelboards is fed simultaneoulsy by primary source(s) of electricity and one or more..."

So no 705.12(D) doesnt apply to 200A panel because 200A panel is not fed simultaneoulsy by more then one sources of electricity. Only one source inverters. No?
 
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hhsting

Senior Member
Ok 705.12(D) does not apply. Aside from load side or not following is necessary for apply:


"...where distribution equipment including switchgear, switchboards or panelboards is fed simultaneoulsy by primary source(s) of electricity and one or more..."

So no 705.12(D) doesnt apply to 200A panel because 200A panel is not fed simultaneoulsy by more then one sources of electricity. Only one source inverters. No?
....
 

ggunn

PE (Electrical), NABCEP certified
So no 705.12(D) doesnt apply to 200A panel because 200A panel is not fed simultaneoulsy by more then one sources of electricity. Only one source inverters. No?
No. If it's connected to the grid it's fed by the grid even if there are no loads in the panel.
 

hhsting

Senior Member
No. If it's connected to the grid it's fed by the grid even if there are no loads in the panel.
You mean the main breaker does not stop the fed from utility? I thought main breaker would allow one way fed from solar to grid.

Also more of the 705.12(D) quote....

"...where this distribution equipment is capable of supplying mulitple branch circuits or feeders or both......"

So where are the branch circuits or feeders in the 200A panelboard? I have none. So how can it apply?

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