Relay / switch to disconnect non-essential loads panel when no grid?

Hi. Is there something like a relay / transfer switch / connector that would disconnect non-essential loads panel when there is no grid?
With manual override option.

I was thinking of something like generator start signal from inverter for NC relay but not sure if it's good solution.

The non-essential panel would be tied to the inverter but I don't want the NELs to consume battery if there is no grid.

It's for 240V devices (A/C, Owen, water heater, EV charger etc), 40-60A minimum (for the whole relay).
Normally I would power them from solar but wouldn't like to drain ma batteries if there is no grid backup during a night or something like that.

I only have lfp4+solar+inverters on boats experience, this is for whole-house system.

Thanks!

A contactor is similar to a relay. But handles much larger loads.

Usually it is the opposite. There is a Critical Loads panel that separates from the rest of the house.

DIYrich said:

Usually it is the opposite. There is a Critical Loads panel that separates from the rest of the house.

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I can understand the desire to run all the loads off batteries during peak periods but only essential loads when grid is down and the kWhs in the batteries might need to last longer than the four hours of peak rates.
There are several solutions. Some inverters use remote sensors to control loads to circuits not connected to inverter. Also auto disconnect switch could be used..There are programmable load centers like Span and SolArk has announced a programmable load panel.

Ampster said:

I can understand the desire to run all the loads off batteries during peak periods but only essential loads when grid is down and the kWhs in the batteries might need to last longer than the four hours of peak rates.
There are several solutions. Some inverters use remote sensors to control loads to circuits not connected to inverter. Also auto disconnect switch could be used..There are programmable load centers like Span and SolArk has announced a programmable load panel.

Click to expand...

This is exactly my case - don't want to run out of batteries if someone turns on the owen in the evening if the grid is down and the batteries are half empty because the EV is being charged.

I just can't find a concrete product - be it a contactor or ATS. Can't find auto disconnect switche that would work like that. I need the control circuit to be different than the pass-through circuit.

ckanu said:

I just can't find a concrete product

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A high Amp double pole relay with a 120 or 240 volt coil would work. You just need to switch L1 and L2. You would wire the relay coil to the grid and use the normally open contacts for the inverter connection to that panel and when the power is out the relay opens. When the grid is up that panel is connected to the inverter and gets grid power from pass through of the grid or solar or batteries depending on how you have the inverter programmed.

When my battery is low.
The non essential loads on my system will fail to various backups. Grid being the last option. If the grid isn't available. Those loads are non functional.

Look up Savant Power. They have individually controlled breakers that can be used to shed load.

I just bought this guy:

It is a double in that it has both an always open and an always closed connection so you can wire it either way.
I plan to use it so that my well pump will turn off the hot water heater to stop from over pushing my inverter.

JeffL said:

I just bought this guy:

https://www.grainger.com/product/DAYTON-Open-Power-Relay-8-Pins-Relay-5X848?analytics=nspNav&opr=NSDSP

It is a double in that it has both an always open and an always closed connection so you can wire it either way.
I plan to use it so that my well pump will turn off the hot water heater to stop from over pushing my inverter.

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Jeff, do you have more details on how this actually works. I have the same problem where I have a hot tub that runs all day at about 300W but then when the jets or the heater come on it can easily jump to about 10kW. I'd like to automatically switch to grid power in these events. Is it possible for this to act like a switch to convert from inverter to grid, or does this just effectively cut off the circuit?

An ATS should do it easily.


You connect the SourceA port on the grid line, the SourceB port on the inverter output, and connect only the AL1, AL2 and AL3 into your grid L1,L2 and N. This way, when you have no grid power, the switch will automatically connect to SourceB, which have nothing connected to, disabling those circuits. They have manual switching too.