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

[William Miller]

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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