Adding a Load to a Dedicated PV Combiner Panel - With a Line Side Tap

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Anode

Member
Location
Washington, USA
I'm thinking there is some code that would prevent us from adding an outlet or circuit to a dedicated pv combiner panel. This combiner panel would be circumventing the 120% rule, as a dedicated pv combiner back feed panel...

I am going through the motions of design right now, and the issue I have is that this system would need to be a line side tap due to its size; however, the microinverters we would be using require the communications to go through the power line, and show in the installation guided connecting to the panel.

Is there a code against adding a load or circuit to that panel designated for pv only? Does it matter that this load is going to be virtually non existent? I know I just read something on this in another thread a week or so ago...
 
I'm thinking there is some code that would prevent us from adding an outlet or circuit to a dedicated pv combiner panel. This combiner panel would be circumventing the 120% rule, as a dedicated pv combiner back feed panel...

I am going through the motions of design right now, and the issue I have is that this system would need to be a line side tap due to its size; however, the microinverters we would be using require the communications to go through the power line, and show in the installation guided connecting to the panel.

Is there a code against adding a load or circuit to that panel designated for pv only? Does it matter that this load is going to be virtually non existent? I know I just read something on this in another thread a week or so ago...

The NEC doesnt use the term or directly address "dedicated PV combiner panels". Washington is on 2014, so see 705.12(D)(2). Basically, in the 2014 there are two alternatives to using the "120%" rule.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
My opinion is that the language of 230.40 prohibits a general purpose outlet on the extra set of service entrance conductors that supply the PV. But since the monitor is really part of the pv system, and also presents no danger I can think of, a reasonable AHJ should allow it, maybe just require some labeling that it's only supposed to be used for the monitor.

Otherwise electrofelon has it right.
 

SolarPro

Senior Member
Location
Austin, TX
If you are on the 2014 Code, then you can follow 705.12(3)(c) for the inverter aggregation panel:

(c) The sum of the ampere ratings of all overcurrent devices on panelboards, both load and supply devices, excluding the rating of the overcurrent device protecting the busbar, shall not exceed the ampacity of the busbar. The rating of the overcurrent device protecting the busbar shall not exceed the rating of the busbar. Permanent warning labels shall be applied to distribution equipment that displays the following or equivalent wording

WARNING:
THIS EQUIPMENT FED BY MULTIPLE SOURCES.
TOTAL RATING OF ALL OVERCURRENT DEVICES,
EXCLUDING MAIN SUPPLY OVERCURRENTDEVICE,
SHALL NOT EXCEED AMPACITY OF BUSBAR.

The warning sign(s) or label (s) shall comply with 110.21(B).

This article on Understanding NEC 2014 and it Impact on PV Systems explains:


Option 3: Subsection (c) specifies that the sum of the overcurrent devices connected to loads and supplies?excluding the rating of the main overcurrent device protecting the busbar?must be limited to an amount less than or equal to the rating of the busbar. The most likely application for this option is at inverter aggregation panels (also known as inverter combiner or accumulation panels), which have long been a potential point of contention for system integrators and AHJs. When this option is employed, a warning label must be applied on the equipment that reads:

WARNING:

THIS EQUIPMENT FED BY MULTIPLE SOURCES.

TOTAL RATING OF ALL OVERCURRENT DEVICES,

EXCLUDING MAIN SUPPLY OVERCURRENT DEVICE,

SHALL NOT EXCEED AMPACITY OF BUSBAR.
 
My opinion is that the language of 230.40 prohibits a general purpose outlet on the extra set of service entrance conductors that supply the PV.

I would agree with that if the "PV disconnect" is a 7th disconnect and/or it is not grouped with the other service disconnects. I dont think the intent of the code is to make a PV system open up a loophole so one can have non grouped service disconnects supplying general circuits. IF however the "PV disconnect" is grouped and 1 of 6, then I say there is technically no way to distinguish it from being just another "normal" set of service entrance conductors and service disconnect.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
I would agree with that if the "PV disconnect" is a 7th disconnect and/or it is not grouped with the other service disconnects. I dont think the intent of the code is to make a PV system open up a loophole so one can have non grouped service disconnects supplying general circuits. IF however the "PV disconnect" is grouped and 1 of 6, then I say there is technically no way to distinguish it from being just another "normal" set of service entrance conductors and service disconnect.

Agreed.
 
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