[RE-wrenches] GEC for Micro-Inverters and ACPV Modules

John Berdner John.Berdner at solaredge.com
Tue Jan 15 08:45:37 PST 2013


Mark:

I don't know the SolarBridge product as well as some others.
Like you, I would ASS U ME the lack of a grounding lug would indicate that a GEC is not needed.
Referring to the manufactures written instructions on grounding in the manual is always the best reference.

You are correct, there are 2 cases where you would not need a GEC per Code.

1) The unit is Listed as an AC Module so it is exempt from DC side requirements.  This is not to be confused with a micro-inverter installed in the field on a module which would still need to meet the DC side requirements.

2) The inverter operates with a floating array, i.e. the array positive or negative (or neutral in a bi-polar array) are not bonded to ground.  Just to clarify one point ... With a floating array the inverter topology could be either isolated (HF or LF transformer) or non-isolated (transformerless).  The main criteria is if array conductors are, or are not, bonded to ground by the inverter (which is not necessarily related to a specific topology).

Best Regards,

John Berdner
General Manager, North America

SolarEdge Technologies, Inc.
3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new address.)
T: 510.498.3201 ext 747
M: 530.277.4894

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
Sent: Monday, January 14, 2013 8:11 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules

I am interested in the SolarBridge , it has no chasis lug so it must not require a GEC, right?

So why does it not require a GEC? Is it because it is not an isolated inverter? Because it is an isolated inverter that does not have a grounded current carrying conductor on the DC side? Because it is listed as an AC module so who cares what is happening on the DC side?

On 1/14/2013 6:52 PM, John Berdner wrote:
> Mark:
>
> The GEC is required if the inverter bonds one of the PV conductors to ground (as Enphase does).
> Enphase support may not have a problem with it but not using a GEC (with all the GEC requirements) on any system with a grounded array is definitely a Code violation in NEC 2008 and 2011.
> I don't recall it being eliminated in the 2014 Code either but could be wrong.
>
> If the inverter does not bond the array positive or array negative to ground then the array is ungrounded so no GEC is required.
> Non-isolated inverters (also referred to as transformerless inverters) do not bond the array negative or array positive to ground and so no GEC is required (EGC is still required).
>
> If you have a Listed AC module then none of the DC side requirements apply so no GEC would be required unless required by the manufacturer's instructions.
> Unfortunately, adding a micro-inverter to a module in the field does not make it a Listed ac module.
>
> Best Regards,
>
> John Berdner
> General Manager, North America
>
> SolarEdge Technologies, Inc.
> 3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new
> address.)
> T: 510.498.3201 ext 747
> M: 530.277.4894
>
>
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark
> Frye
> Sent: Monday, January 14, 2013 3:31 PM
> To: RE-wrenches
> Subject: [RE-wrenches] GEC for Micro-Inverters and ACPV Modules
>
> Does anyone have the latest on the GEC for micro-inverters/ACPV issue?
>
> I know it is still in NEC 2008 and I believe 2011 with plans to address it in 2014.
>
> I am specifically interested in the issue of GEC means continues (irreversible splices) and the whole business of the DC side of these devices constituting a separately derived system.
>
> Enphase technical support is fine if the micro inverter chasis is bonded to a EGC only, but they leave the lug on the chasis if you want/need to build a GEC.
>
> SolarBridge (pre-assembled micro-inverter) seems to be devoid of a chasis lug and therefore by extension does not/can not had a GEC in the system.
>
> Exeltech (integrated micro-inverter aka. ACPV) does not seem to have a lug on its chasis.
>
> Has the industry pretty much moved to not requiring a GEC for these devices and if so, how are the AHJ taking it?
>
> Thanks,
> Mark Frye
> Berkeley Solar Electric Systems
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