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

[Christopher Warfel]

Thanks, the problem is we need it to disconnect only upon loss of 
utility power, and it is on the battery loads panel. The panel for the 
HVAC is in another building that the HVAC serves.

On 8/22/2025 8:20 PM, Chris Sparadeo 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 
> <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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-- 
Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401) 447-5773
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