Connecting off grid inverter to house wiring

Sverige

A Brit in Sweden
Is it ok to permanently join neutral from an off grid inverter to neutral in house wiring distribution board, then switch individual wiring circuits between the inverter live and mains live (with an intermediate ”off“ position, so power doesn’t switch directly from mains to inverter without a pause)?
 

LarsJ

New Member
Be safe and use either an automatic switch or manual transfer switch, because you are liable if you energize a power line while linesmen are up there and they're fried. If you go with industry standard equipment, you will have less liability in the end.
I bought the Reliance Controls 510-C (120/240v, 10 circuits) manual transfer switch to handle later additions. It's way overkill for the single kW of panels I now have, but a new roof comes first.
 

dmitrimedina

New Member
Is it ok to permanently join neutral from an off grid inverter to neutral in house wiring distribution board, then switch individual wiring circuits between the inverter live and mains live (with an intermediate ”off“ position, so power doesn’t switch directly from mains to inverter without a pause)?
I do something similar in my house I put and off grid all in one inverter controller to have the input from the main grid from the breakers panel in the main meter, then I disconnect the cables that’s goes from this breakers to power the houses and I connect those cables to the inverter output. So now the main power run from the mains meter to the inverter to the house and of course I have the batteries connected to the machine and the solar panels. The benefits of this is that you don’t make backfeeding never and you don’t need all the paper work because the system still working off grid
 

Sverige

A Brit in Sweden
Be safe and use either an automatic switch or manual transfer switch, because you are liable if you energize a power line while linesmen are up there and they're fried. If you go with industry standard equipment, you will have less liability in the end.
I bought the Reliance Controls 510-C (120/240v, 10 circuits) manual transfer switch to handle later additions. It's way overkill for the single kW of panels I now have, but a new roof comes first.
Thanks - the inverter live would only ever be switched to the house wiring circuits, and only when the mains live was disconnected of course. It’s really just a question of whether need a second pole of switching to disconnect mains neutral before inverter neutral connects, or if the two can be safely commoned.
 

Sverige

A Brit in Sweden
I do something similar in my house I put and off grid all in one inverter controller to have the input from the main grid from the breakers panel in the main meter, then I disconnect the cables that’s goes from this breakers to power the houses and I connect those cables to the inverter output. So now the main power run from the mains meter to the inverter to the house and of course I have the batteries connected to the machine and the solar panels. The benefits of this is that you don’t make backfeeding never and you don’t need all the paper work because the system still working off grid

thanks - sounds interesting. What is the “off grid all in one inverter controller“ you mentioned? Is it a product you can provide a link to?

So it sounds like you’re switching the input of your distribution board between inverter and mains, so only one is connected at each time. Are you also switching the neutral side of the distribution board input from mains supply to inverter, or are you just switching the live?
 

dmitrimedina

New Member
thanks - sounds interesting. What is the “off grid all in one inverter controller“ you mentioned? Is it a product you can provide a link to?

So it sounds like you’re switching the input of your distribution board between inverter and mains, so only one is connected at each time. Are you also switching the neutral side of the distribution board input from mains supply to inverter, or are you just switching the live?
This is the machine and this outlet is the one who provide the output in which the plug is connected to the ground and live of the house and the second outlet is the one that’s it’s connected to the main meter breakers so it provide the main grid electricity to the inverter with the plug
 

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Sverige

A Brit in Sweden
Thanks @dmitrimedina, so it seems like that is a hybrid inverter with an MPPT charge controller built in, and the inverter accepts a mains input then switches the output circuits between solar / mains depending on how you program it? That’s a neat solution, but not an option for me as I’m using 4S LiFePo4 and already have an off grid inverter and charge controllers.
 

dmitrimedina

New Member
Correct I put it on solar panel priority mode so in the day it’s use the solar panels an at night the main grid. I have it with 4 LiFePo4 12 volts batteries in series to obtain the 48volt the inverter need. The off grid inverter of you have the AC input for the main grid
 

Sverige

A Brit in Sweden
Correct I put it on solar panel priority mode so in the day it’s use the solar panels an at night the main grid. I have it with 4 LiFePo4 12 volts batteries in series to obtain the 48volt the inverter need. The off grid inverter of you have the AC input for the main grid
Thanks (y)
 

Jim in NH

New Member
Be safe and use either an automatic switch or manual transfer switch, because you are liable if you energize a power line while linesmen are up there and they're fried. If you go with industry standard equipment, you will have less liability in the end.
I bought the Reliance Controls 510-C (120/240v, 10 circuits) manual transfer switch to handle later additions. It's way overkill for the single kW of panels I now have, but a new roof comes first.
I used the Reliance Controls (120v, 6 circuits) manual transfer switch. When I switch a circuit from Line to Gen (Growatt) if the particular breaker on that circuit in the main panel is a GFI or Arc Fault breaker it trips... I have not been able to figure out why...
 

FilterGuy

What, me worry?
The root of the question seems to be: Do I have to switch both neutral and Hot at the transfer switch?

The definitive answer to that is...... maybe.

It all depends on how your utility grid network and how your generator handles ground and neutral bonds. Since I don't know the standard where you are, I can't really advise you.
 
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