Balcony "on-grid" system. Can it work off-grid too?

I am new to Solar, but have been watching a lot of YouTube guides, including of our host, and reading online too.
I am seeing this system pop up on Amazon in Europe
I am new to these on-grid-only systems, but from reading it seems that the AC out goes into the house's AC out (!)
That got me worried that having 2 ACs plugged into each other is a recipe for
However, it seems that this is working by the on-grid inverter latching onto the sine wave of the house's electricity and basically working in tandem
That got me thinking : could you not use a portable power station, plug a solid AC power splitter into it, then the on-grid inverter AC out to the first socket on the AC splitter and then the load (e.g. fridge) to the second socket on the AC splitter?
Or will it and if so, why?
Thanks I'm advance.

If you tried to hook up a portable power station this way, it most likely would fry or hopefully trip the breaker before that happens.

What you're describing is called grid synchronization it's what happens when you connect your grid-tied inverter to the main panel of your home. However, a grid-tied inverter knows to sync the AC frequency and will shut off to prevent backfeed when the power goes out. This means a grid-tied solar system only works when the grid is up, and by code/design will shut down when the grid goes down.



Take a look at this video, this will help explain the hardware and wiring necessary if you want to use a portable power station as a backup for your home.

Thanks!
However, look at the description and photos on the link I sent. This grid-tied system's AC out is meant to be plugged directly (!) into the mains socket of your house.
Just to be clear, my question was if it was possible to convert that system safely to an off-grid one.
On that setup potentially frying the power station: why would it fry a power station and not our house installation?
Is it because the parallel connection of AC (the solar inverter + power station) will push current into the weaker load? And the power station has much more sensitive electronics inside?
I thought those systems had settings on the app to give priority to either the grid or to the solar inverter. So, if you give priority to the "grid" (the power station), so that the solar only tops up, would it not be safe?
Sorry for stupid questions

Kbeam said:

Thanks!
However, look at the description and photos on the link I sent. This grid-tied system's AC out is meant to be plugged directly (!) into the mains socket of your house.
Just to be clear, my question was if it was possible to convert that system safely to an off-grid one.
On that setup potentially frying the power station: why would it fry a power station and not our house installation?
Is it because the parallel connection of AC (the solar inverter + power station) will push current into the weaker load? And the power station has much more sensitive electronics inside?
I thought those systems had settings on the app to give priority to either the grid or to the solar inverter. So, if you give priority to the "grid" (the power station), so that the solar only tops up, would it not be safe?
Sorry for stupid questions

Click to expand...

Your questions are not stupid. Better ask before doing damage...
The problem is that if you don't have enough loads at any certain time, the power from the grid tied system has no where to go, and will damage the power station.

Think of the grid is an "endless" pool of power. Grid tied system push power to thus endless pool, so no problem. But if you have a small, limited pool and you pour more water into it, it will overflow at some time.

Kbeam said:

However, look at the description and photos on the link I sent. This grid-tied system's AC out is meant to be plugged directly (!) into the mains socket of your house.
Just to be clear, my question was if it was possible to convert that system safely to an off-grid one.

Click to expand...

Short answer: no.

Longer answer: you'd need to switch inverters AND rewire your panel AND get some batteries, so it's not easy.

On that setup potentially frying the power station: why would it fry a power station and not our house installation?

Click to expand...

It would not do either one. It would shut down. It is designed with several mechanisms to detect a grid failure and shut down; this feature is called "anti-islanding." Since islanding is what you want to have happen for an off grid system, this is exactly the wrong inverter for that application.

OK, got it! So, no way to retrofit that grid-tied system into an off-grid system. Thanks for the clarifications!

There are some YT videos of people who have tried. That unit will try to overvoltage the pilot inverter by raising the voltage until the panels have supplied all they can. This blows the inverter capacitors and can over voltage the FETs. The system can't overpower the grid. Yes, it can be made to work by monitoring the voltage and providing a proportional dump load like a water heater. There has to be assurance that a dump is always available. The power from the panels can also be throttled when excess is determined.

See

Kbeam said:

OK, got it! So, no way to retrofit that grid-tied system into an off-grid system. Thanks for the clarifications!

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There is a way, but you need another inverter EG4 or Sol-Ark are the two I know for certain that support AC coupling. You would isolate that grid tied system to the gen input on the inverter and the inverter would raise or lower the AC frequency to turn on or off the solar system.

But buying a $4-$6K inverter and wiring that all in so you can use a cheap solar system from Amazon IMO doesn’t make financial sense…. But it would do what you’re trying to do.

MaikaiLife said:

There is a way, but you need another inverter EG4 or Sol-Ark are the two I know for certain that support AC coupling. You would isolate that grid tied system to the gen input on the inverter and the inverter would raise or lower the AC frequency to turn on or off the solar system.

But buying a $4-$6K inverter and wiring that all in so you can use a cheap solar system from Amazon IMO doesn’t make financial sense…. But it would do what you’re trying to do.

Click to expand...

And this is aimed at apartment dwellers - they don't generally have access to the power room to hook anything up.

So it is limited to what current can be pushed over the wires - 130vac 15amp - most internal house wiring is 14awg, so 1800w maximum but in reality with losses from conversion and such you would only see around 1200w or so at the inverter out and that is only with grid voltage on.

They did some spiffy design work with the connectors for this - hub plugs into the back of the machine then a not-so-sucide cord plugs into that. Only after voltage is sensed does it sync up the frequecy and start putting out power.

The only real problem with these would be push back from the POCO because of how they connect to the grid without an interconnect agreement.

That and it is typical here that the power goes off and on and off and on when power is restored - not sure how they behave in that situation.

In Europe the voltage is twice that here so the current is half. Less potential issues with house wiring for same wattage.