[RE-wrenches] Powerwall 3

[Vincent Jolissaint]

Jason,
There are 2 different methods typically utilized, one specified by Tesla
for any UL2703 module/racking combination which is as you say and limits
the MCI to 165V, which is the tested disconnect limit of the MCI-2.

If you use the MCI-1 then you have an additional option of using the 3741
PVHCS listing of another manufacturer such as Ironridge. Since the MCI-1
has a 600V disconnect limit, you can safely use just (2) MCI-1 on a string,
one at the beginning and end, as long as the array is physically contiguous
with no gaps larger than 2' between adjacent modules.

The GW2/3 is irrelevant to the MCI question, as the Powerwall 3 inverter
sends its keep alive signal with PLC over the DC wiring.

I think you could make a temporary off grid system work well enough if you
simply commissioned it with grid voltage, then removed the grid, but kept
the islanding contactor intact. Either GW3/GW2 or the Backup Switch in a
meter socket enclosure could serve as this contactor, to keep the PW3 happy
and in communication with "the grid."

On a separate note, the details and testing of a 3741 PVHCS listing
probably means that module level rapid shutdown never added much first
responders safety compared with rooftop shutdown at within 1' of the array
group. I have seen others on this list agree to as much and the test labs
basically validate this in my eyes.

From: Jason Szumlanski <jason at floridasolardesigngroup.com>
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Cc: Vincent Jolissaint <vincentj at cobaltpower.com>
Subject: Re: [RE-wrenches] Powerwall 3 (contd)
Message-ID:
        <70929283-0f8f-f810-c3c7-9716cfd0e77b at floridasolardesigngroup.com>
Content-Type: text/plain; charset="utf-8"

Thanks,?Vincent. This is the information I needed.


I did read that at least 1 MCI is needed even if you do not require RSD.
The MCI
instructions are a bit confusing. I know for RSD you need one at the start
of a
string and at least one every three modules, but it's unclear if you need
the
MCI-1 or MCI-2 when using the GW3.


The reason I was thinking about an off-grid application is I want to use
one PW3
in a mobile application (for myself). I was thinking about tricking it into
working, but I think it would?take a?PW3, GW2 or GW3, and an AC source
to?commission it initially.

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208


On Wed, Sep 11, 2024 at 4:18?PM Vincent Jolissaint via RE-wrenches
<re-wrenches at lists.re-wrenches.org> wrote:

> (sorry sent the previous reply before it was complete)
> Hi Jason,
>
>
> Currently Tesla doesn't allow any totally off-grid installations with PW3
or
> PW3, they used to support this through the Gateway but no longer do.
>
>
> In addition, the Powerwall 3 will require at least a single MCI per
string to
> pass the self?test function. This also limits the total string loop length
> from MPPT+ to MPPT-.
>
>
> Powerwall 3 does contain the site controller, but it will require some
> islanding contactor to function properly.
>
>
>
> Vince Jolissaint?|?Director of CAD Services
>
> 2557 Wyandotte Street | Mountain View, CA? 94043
> Office:?650.938.9574 | Email:?vincentj at cobaltpower.com
> [vincentj at cobaltpower.com]
>
>
>
> >From: Jason Szumlanski <jason at floridasolardesigngroup.com
> [jason at floridasolardesigngroup.com]>
> >To: RE-wrenches <re-wrenches at lists.re-wrenches.org
> [re-wrenches at lists.re-wrenches.org]>
> >Subject: [RE-wrenches] Powerwall 3
> >Message-ID:
> ?>? ? ? ?<CAE438R9LWo_VNuTTkOzVbv62LST3_Bf4-x7VfLm=-
Rkk6k+wJw at mail.gmail.com
> [Rkk6k%2BwJw at mail.gmail.com]>
> >Content-Type: text/plain; charset="utf-8"
>
> >Certified Powerwall installers,
>
> >Can the PW3 be commissioned for for a completely off-grid system with DC
> >coupled solar panels with no MCIs. If so, do you need a Gateway 2/3, or
can
> >it operate autonomously in this scenario without a Gateway?
> >
> >Jason Szumlanski
> >Florida Solar Design Group

*Vince Jolissaint |* *Director of CAD Services*

2557 Wyandotte Street | Mountain View, CA  94043
Office: 650.938.9574 | Email: vincentj at cobaltpower.com
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