Do I need a transfer switch with Sunsynk inverter?

[SenileOldGit]

I am about to buy a Sunsynk inverter and get it installed by an MCS certified electrician. The electrician told me that I won't need a transfer switch, because the Sunsynk inverters don't need them, and will supply power to the house due to the 'anti islanding' function - but I want the transfer switch in case the inverter stops working, so I can divert the grid straight into the house, rather than into the inverter.
Is my electrician right, and did I misunderstand what he said? I can't see how a faulty inverter can pass through electricity from the grid to the house, unless it uses a relay to divert the electricity through the inverter when the inverter is working, and then the relay defaults back to a 'pass through' mode. Can any Sunsynk owners help me out?

 

[houseofancients]

You don't need them perse, however, if you need to do maintenance and still require your home to be powered, and ATS will come in mighty handy..

That is, if you installer installs it between your grid and your loads. ( grid-in for grid and loads port to your breaker panel)

Seen quite a few installations where a "lazy" installer only installs the grid port, leaving folks without power upon grid outage/failure

So I have one installed with my sunsynk's

 

[Kenny_]

I don't see why an independent transfer switch would not be a bad idea.

 

[houseofancients]

I don't see why an independent transfer switch would not be a bad idea.

You probably mean : why an independant transfer switch would be a bad idea

 

[Kenny_]

What I mean is it is a good idea. ???

 

[DIYrich]

For taking the inverter out of the circuit, you will need two manual transfer switches. First to move grid power from inverter to bypass, and second to move load from inverter to bypass.

 

[houseofancients]

For taking the inverter out of the circuit, you will need two manual transfer switches. First to move grid power from inverter to bypass, and second to move load from inverter to bypass.

A breaker on the grid in grid-in and ATS should be sufficient to isolate, or am I missing something ?

 

[DIYrich]

A breaker on the grid in grid-in and ATS should be sufficient to isolate, or am I missing something ?

How will you get power to the load?

 

[houseofancients]

How will you get power to the load?

Grid is busbarred between non critical, ATS and grid-in inverter ( that is how it is installed here)
Here in the EU dinrail breaker panels and busbars are more common than in the us

 

[BentleyJ]

It depends on how the inverter is wired into the main or subpanel. I would suggest using the term "Maintenance Bypass" in a situation like this to distinguish between the internal Transfer Switch (disconnect/anti-islanding) built into the inverter vs. an external transfer switch that is used as means of by passing the inverter.

Could you post a pic or simple diagram?

 

[DIYrich]

Grid is busbarred between non critical, ATS and grid-in inverter ( that is how it is installed here)
Here in the EU dinrail breaker panels and busbars are more common than in the us

That would work. Not sure about ATS vs manual. If I was taking the inverter out of the circuit, I would want the certainty of a MTS. I suppose if the inverter fails, then ATS to grid might be helpful. But then you might not notice for a while that it failed.

 

[houseofancients]

Sunsynk app ( or pvpro), will send out push notification ( and in case or the sunsynk app VERY clearly )

 

[timselectric]

The electrician is correct. You don't need an external transfer switch for it to work.
And you are correct.
An external transfer switch will allow you to bypass the system and power your loads directly from the grid.
It can be either a manual or automatic transfer switch.
Personally I prefer automatic. If the inverter shuts down when I'm away. I want the food in the fridge to be saved.

 

[SenileOldGit]

Thank you all for your replies - I don't know how it's going to be wired, because the electrician hasn't got that far yet.
So is he correct when he says that I don't need a transfer switch, because if the inverter stops working for some reason, it will allow the grid supply to flow through it and straight into my consumer unit box? (Presumably along the same cables as any power produced by the inverter would travel.)
I think I would like to be able to 'divert' the grid supply away from the inverters and straight into the house, otherwise how can you do work on the inverters while still keeping the house powered (so if I turned off the AC breaker going into the inverter (with no transfer switch installed), the inverter will have no grid supply going into it, but therefore neither will the house!)

 

[DIYrich]

I suggest you diagram what you want for the Electrician to install. Then there is no disagreement on the final product.

 

[timselectric]

So is he correct when he says that I don't need a transfer switch, because if the inverter stops working for some reason, it will allow the grid supply to flow through it and straight into my consumer unit box? (Presumably along the same cables as any power produced by the inverter would travel.)

He is correct, as long as the unit doesn't fail to do so.

I think I would like to be able to 'divert' the grid supply away from the inverters and straight into the house, otherwise how can you do work on the inverters while still keeping the house powered

Definitely the best option.

(so if I turned off the AC breaker going into the inverter (with no transfer switch installed), the inverter will have no grid supply going into it, but therefore neither will the house!)

Correct.

 

[SenileOldGit]

How do you set up a non-export capable inverter (such as a Voltacon) with transfer switches, so that in the event of a power cut, no electricity from the inverter can go back down the line into the grid, while the inverter is still on and powering the house?