[RE-wrenches] ATS models to bypass GT hybrid inverters for maintenance/faults

Tue Jan 14 12:17:10 PST 2025

We tend to do this on every install in the Bahamas, except that we install
a manual transfer switch instead of an automatic one.
It's a bit of a (minor) pain for the customer, but a very reasonably priced
add on as "emergency" backup. We haven't had any trouble selling the logic
of it to the client, either

Daryl

On Tue, Jan 14, 2025, 3:13 PM david quattro via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I’ve been doing this for a few years now, but not on every install.
> They’re pretty expensive, more labor, one more component to fail, and takes
> up significant wall space/aesthetic factor.
>     GENERAC transfer switch requires you to rig a separate 12v power
> supply, (normally this 12vdc comes from the generator start battery)  to
> triggers transfer you have to trick the control module by shorting
> “23Transfer” to Ground. Here is an excellent YouTube video demonstration.
> https://youtu.be/rT_3JYZS9Mg?si=7EarqHXTddLSpKXe
>     KOHLER:  use their RDT model !  Don’t use the RXT model, as their RXT
> really does need a complex computer handshake signal from a true Kohler
> generator.  The  _RDT_  is sweet - senses primary versus secondary, and
> switches back and forth automatically.
> David Q
>
>
>
> On Tue, Jan 14, 2025 at 11:36 AM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Stuart:
>>
>>
>>
>> I understand the concern and appreciate the consideration to provide more
>> reliability.  The approach you suggested sounds like a band-aid, not a
>> cure.
>>
>>
>>
>> I do not know if this complete shutdown is required by the listing (a
>> feature) or is just a bug.  Does anyone have information on this?  If it is
>> not required, the manufacturers should certainly correct these problems.
>>
>>
>>
>> This may be a case against All-in-on inverters.  If there is a PV arc
>> fault on systems with separate charge controllers the inverter will not
>> curtail operation and it’s pass-through capabilities.
>>
>>
>>
>> William Miller
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Stuart Kriendler via RE-wrenches
>> *Sent:* Tuesday, January 14, 2025 11:09 AM
>> *To:* re-wrenches at lists.re-wrenches.org
>> *Cc:* Stuart Kriendler
>> *Subject:* [RE-wrenches] ATS models to bypass GT hybrid inverters for
>> maintenance/faults
>>
>>
>>
>> Good day Wrenches,
>>
>>
>>
>> 2025 looks to be the year for installing more grid tied (GT) battery back
>> up hybrid inverters on new and existing GT PV systems in a whole house
>> backup scenario
>>
>> i.e. Utility - Hybrid Inverter - House Loads
>>
>>
>>
>> With these newer GT hybrids so 'sensitive', any fault on the PV side can
>> cause them to shut down, thus stopping power to the house.
>>
>> To minimise this it seems sensible to add an ATS to the system such that
>> if/when the hybrid faults, the ATS w switch to grid power, bypass the
>> hybrid, and power the house.
>>
>> This could save an emergency truck roll or late night phone call for
>> installers.
>>
>>
>>
>> Anyone have experience on good value-for-money Listed automatic transfer
>> switches that would do the job, 200A, 120/240V?
>>
>>
>>
>> Two name brand options that came up on the less expensive end of the
>> spectrum are:
>>
>> - Generac RXSW200A3 (
>> https://www.generac.com/residential-products/standby-generator-transfer-switches/automatic/rxsw200a3/
>> )
>>
>>
>>
>> - *Kohler 200-amp, Service Entrance RXT ATS | RXT-JFNC-200ASEQS4 (*
>> https://www.kohler.com/content/dam/kohler-com-NA/Lifestyle/PDF/PDF-g11152.pdf
>> )
>>
>>
>>
>> However, they each say their ATSs must be used with the corresponding
>> generator.
>>
>>
>>
>> I would imagine a simple 'grid sense' functionality would mean that if
>> the hybrid's output was connected to the Grid/Normal lugs and the grid was
>> connected to the Gene/Backup lugs in the ATS it should work.
>>
>> However I don't want to end up with an expensive surprise in a relatively
>> remote location where I operate!
>>
>>
>>
>> Would appreciate any feedback with experience with the above or other ATS
>> models or how people are future proofing for this scenario?
>> To do future maintenance/torque checks etc. in a GT hybrid whole home
>> backup situation, it would be nice to bypass the inverter and keep the
>> house powered for safety and homeowner convenience in general.
>>
>>
>>
>> Thanks and best.
>>
>>
>>
>> Sunniest regards,
>>
>> Stuart
>>
>> 441 599 2105
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