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

[Stuart Kriendler]

Thanks Jerry, very good to know.

So the Kohler RXT ATS would automatically switch from Primary to Back up as
soon as power is lost of primary?
The documentation suggests that it 'must be connected to a generator set
equipped with the Kohlerr RDC2 or DC2 generator/transfer switch controller'
which made me concerned.

AC coupling is going to be very common for us in GT retrofit for sure!
I'm loving the MN AIO for its ability to AC couple an existing string/micro
inverter's output, as well as expand the system with DC coupling AND have a
dedicated gene input (which took the juice of a real crappy old B&G gene
set that needs new brushes) AND have another dedicated smart breaker that
can control loads based on SoC (or V for lead) via the app.

Much appreciated, be great to work with the RXT if it can switch based on
not seeing power without the RDC2 module as there are some stock and a
supplier when the RXT contactors fail/get sticky, I've heard that can
happen on X out of 100.

Sunniest regards,
Stuart
441 599 2105


On Tue, 14 Jan 2025 at 15:42, Jerry Shafer <jerrysgarage01 at gmail.com> wrote:

> Asco and kohler both are good, and have used them on AC coupled systems
> with great success.  Ya l know AC coupled is not the ideal but in
> retrofitting it's very common unless you also can replace the inverter with
> something like Solark.
>
> On Tue, Jan 14, 2025, 11:10 AM Stuart Kriendler via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> 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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