[RE-wrenches] How to shed a load in a subpanel that is in a building other than where the solar system is interconnected

[Kirk Herander]

There is a company called Savant, I’ve seen their individual Smart breakers
installed in sqd Panels - they are individual smart breakers. A single pole
breaker would actually take up two slots one for the OCPD itself, and one
for the sp relay. Don’t know exactly how it operates, but I know you don’t
have to buy an entire smart panel for it to work.

As discussed on this forum, also, there are also RF transmitter/ receivers,
which can do what you ask. Used them to disconnect an inverter from a
common AC bus when the gennie turns on.



*Kirk Herander / **kirkh at vermont.solar <kirkh at vermont.solar>*

*Owner|Principal, VT Solar, LLC*

*Celebrating our 34st Anniversary 1991-2025!!*

dba Vermont Solar Engineering

802.559.1225


On Fri, Aug 22, 2025 at 8:21 PM Chris Sparadeo via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi Chris,
>
> I’m wondering if a load management device like this could be helpful?
> However, it does not discern between grid presence and island mode, so it
> might not fit the bill.
>
>
> https://www.getstepwise.com/product?gad_source=1&gad_campaignid=22363404421&gclid=Cj0KCQjwqqDFBhDhARIsAIHTlkub687mJZYb6g0nIR33X1eA2FVY3bMc_zBxMr44IEl5a7QenVljhUgaArKeEALw_wcB
>
> Quick caveat that shedding an HVAC unit potentially mid cycle is not ideal
> for the health of that unit…but neither is an overload and subsequent power
> failure.
>
> I do know that Lumin Smart sells remote CTs for grid detection. Might be
> worth a call to them to see if this fairly inexpensive product can pair
> with a remote contactor to open the HVAC circuit.
>
> Best of luck!
>
> -Chris
>
> On Fri, Aug 22, 2025 at 3:54 PM Christopher Warfel via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> We installed a 4kW Outback multimode system about 8 years ago.  An
>> electrician came in afterwards and installed 3 heat pumps on the battery
>> backed up power panels.  The Outback inverter disconnected on load every
>> time there was a power outage. The electrician really messed up and is
>> long gone. Also found out did not pull a permit. But I digress.  We
>> managed to move two of the heat pump circuit breakers to the utility
>> panel, so no longer on the battery backed up power panels.  The third
>> heat pump is the problem as it is located in an apartment building
>> remote from the main house. The whole apartment subpanel, including the
>> heat pump load  is interconnected to the "main" battery backed up power
>> panel in the home.
>>
>> A master electrician and I are considering how to shed the apartment
>> heat pump in a power outage.  We cannot easily run a separate circuit to
>> the apartment building to pick up this load.  We have considered a smart
>> panel, but the cost seems high for one circuit. Does anyone know of a
>> power line product of RF product or similar that could operate this
>> breaker when the main service panel loses power? I have been
>> unsuccessful over months of sporadic research.
>>
>> Thanks in advance.
>>
>>
>> Chris
>>
>>
>>
>>
>>
>>
>>
>>
>> -- Christopher Warfel, PE ENTECH Engineering, Inc. PO Box 871, Block
>> Island, RI 02807 (401) 447-5773
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