[RE-wrenches] Transformerless inverter conversion

[August Goers]

Hi William - I think this article by Bill Brooks directly answers both of
your questions:

https://www.southportland.org/files/8814/8156/0204/NEC_2017_Updates_for_PV_Systems___SolarPro_Magazine.pdf

-August


On Thu, Sep 16, 2021 at 9:19 AM William Miller <william at millersolar.com>
wrote:

> Friends:
>
>
>
> Thanks to all of you for your valuable input on the repowering project I
> am researching.  I am learning a lot in the process and generating more
> questions as I proceed.  Here is are questions that came up, and if any of
> you have insight, I would love to hear it:
>
>
>
> 1.   Array OCPD/disconnecting.  The existing array has fuses in the
> positive leads only.  If we were to upgrade to transformerless inverters,
> will we be required to install OCPD in the negative leads as well?  (In
> researching this I came upon this entry in 2017 NEC 690.9: *Informational
> Note: Due to improved ground-fault protection required in PV systems by
> 690.41(B), a single overcurrent protective device in either the positive or
> negative conductors of a PV system in combination with this ground-fault
> protection provides adequate overcurrent protection.*)
>
> *2.   *In the 2014 NEC when installing Ungrounded PV systems, the
> following requirement appeared in 690.35:  *Conductors listed and
> identified as PV wire installed as exposed, single conductors…*  What
> happened to 690.35, and can I now use USE-2 on transformerless inverter
> installations?
>
>
>
> Thanks in advance.
>
>
>
> William Miller
>
>
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com
>
> CA Lic. 773985
>
>
>
>
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