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

[Stuart Kriendler]

Much appreciated August,

Yes, that fancy Enphase System Controller is a nice piece of kit, overseen
a few of those and it is nice they pass through the grid power if there is
an issue, most of the time.
;-)
I'm in love with the MN AIO, the build quality is impressive and great
value for money, with the CBI breakers and features mentioned earlier etc.
all built in.
Now seen an engineering sample do the business in an rugged off-grid
scenario for a few months and feel confident it will be a great GT hybrid
option, one catch is the need for a 3rd party ATS though.
(Hoping Midnite will make one of their own in time, as well as a wireway to
marry the PowerFlo 16 and AIO, both such nicely built solid equipment).

Hopefully the Kohler RXT or Generac can work to keep the ATS cost below
$1k!

Sunniest regards,
Stuart
441 599 2105


On Tue, 14 Jan 2025 at 16:02, August Goers <august at luminalt.com> wrote:

> Hi Stuart -
>
> Many grid tied PV/ESS manufacturers (Enphase, SolarEdge, Franklin, Tesla
> to name a few) now have a Microgrid Interconnect Device (MID) that
> essentially acts as a smart transfer switch thus eliminating the need for a
> 3rd party automatic transfer switch. What brands equipment are you looking
> at?
>
> Best, August
>
> On Tue, Jan 14, 2025 at 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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