[RE-wrenches] Adding battery to grid tie

Sat Aug 9 10:45:48 PDT 2025

Ok: Priority loads.

William Miller
Miller Solar.com
805-438-5600
www.millersolar.com

On Sat, Aug 9, 2025 at 10:26 AM Foxfire Energy <dan at foxfire-energy.com>
wrote:

> Umm, just an FYI, I actually got dinged for labeling the AC output panel
> from a battery backup inverter as "Critical Loads".. Critical loads
> (Critical Branch circuits) are defined in article 100 of the NEC as
> circuits associated with Patient Care.. AC loads from battery backup
> inverters are more appropriately defined as "Dedicated Loads"..
> Maybe someone could correct me here, but I'm under the impression most
> garden-variety inverters are not rated for Critical Load applications.
> db
> ------------------------------
> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf
> of William Miller via RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Sent:* Saturday, August 9, 2025 1:03 PM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Cc:* William Miller <william at millersolar.com>
> *Subject:* Re: [RE-wrenches] Adding battery to grid tie
>
> Correct me if I'm wrong:  I believe AIOs can accept AC coupled power
> through the load ‘output’ port. That leaves the Grid and Gen inputs free
> for their roles as labelled.
>
> The AC coupled inverters connect via a breaker in the critical loads
> panel.
>
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
>
> On Sat, Aug 9, 2025 at 9:50 AM david quattro via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> True.  if you want to do grid, gen, and AC Couple then you need a transfer
> switch or contactor.
>        Likewise I haven’t touched a Powerwall, nor an Enphase battery.
>
>
>
> On Sat, Aug 9, 2025 at 9:36 AM jay via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> One big issue with the AIO’s is that you can’t do grid, generator and ac
> coupling to the best of my understanding
>
> I do like the idea of just removing the old GT inverter and stuffing that
> into the AIO, elegant
>
> yes its my understanding that Tesla won’t accept generator.  While many
> are pissed off at eg4, I won’t touch tesla.
>
> and FYI you can buy the same inverter at Fortress.
>
> thanks everyone.
>
> jay
>
>
>
> On Aug 9, 2025, at 10:28 AM, Tyrone Houck via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Midnite AIO and Sol-Ark both work great for AC coupling in my experience.
> If anyone is new to "All In One" inverters I recommend having tech support
> walk you through commissioning, check firmware, etc. the first time.
>
>
>
>
> On Sat, Aug 9, 2025, 8:47 AM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Two options:
>
> 1. AC couple existing inverter to a battery capable inverter.
>
> 2. Replace existing inverter.
>
> I favor option 2.
>
> Option 1 is only preferred if gaining access to the existing inverter for
> replacement is difficult. An example would be a micro-inverter system.
>
> New AIO inverters allow true high voltage PV input so the existing
> stringing will probably not need to be modified.
>
> I’m new to this so type of upgrade so I welcome any corrections to these
> opinions.  I did replace a Sunny Boy in my shop with a Soul Ark and it’s
> working great!
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
>
> On Sat, Aug 9, 2025 at 8:26 AM Jay via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Is there a consensus as to what equipment to use for adding battery backup
> to normal GT inverter?
>
>
>
> I’ve had a few people ask and I actually haven’t done it.
>
> Thx
> Jay
>
>
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