Neutral/earth bond for inverters

[Isetech]

If you installed an Axpert type inverter, chances are you have bonded the neutral to earth, between the inverter output terminal and the top of the output earth leakage unit, and you dont have an earth earth leakage on the inverter supply. The debate about supplying the inverter via an earth leakage would be an interesting one.

I will soon be adding a Sunsynk 5 kva inverter to my workbench, this is were it gets a little complicated. I have been doing some research into this inverter (for about 2 years) because I just dont have the funds to outlay on a Victron unit yet, maybe once I get my Bugatti, all the blue will blend together in the garage.

It seems people use an external neutral earth bridge connected using a relay. The sunsynk is a hybrid which complicates things a little, capable of receiving and send power back to the grid. There seems to be a lot of confusion about this.

Anyone has a simple explanation which is easy for everyone to understand.

[Justloadit]

A statement by someone about Sengen -

I spoke to the guys from Segen who are also selling the Sunsync now. They said the inverter has a built in earth neutral bond and that bonding is only recommended at one single point and that a permanent bond can cause impedance issues.

[Justloadit]

Check this video
Automatic Neutral Earth Bonding

Do a google search on SunSync videos, lots of training materials.
I have the Deye which is made in the same factory, can state that I am very happy with it, and it does what the manual says.
Since installing it, I save about 50% on my electricity bill, but bear in mind, that my 2 geysers geysers is running on my own designed Dual Usedasun Geyser System so is not even part of the savings

[Isetech]

Note the reference to class I and class II products.

Something else the I am still trying to wrap my head around, how I will fit a changeover/bypass switch in this system and as he mentions is not required.

https://www.youtube.com/watch?v=QtDb...hannel=Sunsynk

[recre8]

What I did with my Sunsynk/Deye inverter was to ignore the "island" output of the inverter you would normally use to power a relay to do the earth-neutral bond. Instead I installed a Hager 25A 1NO+1NC contactor in the DB. The contactor will close whenever grid power is lost and bond neutral to earth - and obviously when power restored, the contactor will open and break the bond. No particular reason other than it being neater in my opinion having it in the DB vs having it in the inverter cubby. Another reason I prefer doing it this way: The contactor will open immediately when grid power is restored whereas with the inverter, it will keep the relay powered (and thus the bond) until it synchronizes with the grid. By default configuration that is 60 seconds.

As for my earth leakage. I have two earth leakages. One for the grid, and another for the UPS output of the inverter. Both having their own separate neutral bars. The automatic transfer switches that I use will then switch the relevant circuits to either UPS Live+Neutral or Grid Live+Neutral.

[Isetech]

What I did with my Sunsynk/Deye inverter was to ignore the "island" output of the inverter you would normally use to power a relay to do the earth-neutral bond. Instead I installed a Hager 25A 1NO+1NC contactor in the DB. The contactor will close whenever grid power is lost and bond neutral to earth - and obviously when power restored, the contactor will open and break the bond. No particular reason other than it being neater in my opinion having it in the DB vs having it in the inverter cubby. Another reason I prefer doing it this way: The contactor will open immediately when grid power is restored whereas with the inverter, it will keep the relay powered (and thus the bond) until it synchronizes with the grid. By default configuration that is 60 seconds.

As for my earth leakage. I have two earth leakages. One for the grid, and another for the UPS output of the inverter. Both having their own separate neutral bars. The automatic transfer switches that I use will then switch the relevant circuits to either UPS Live+Neutral or Grid Live+Neutral.

A smart idea to make it a fail safe way of doing it, if the relay fails, it will trip your grid E/L unit.

[Isetech]

As for my earth leakage. I have two earth leakages. One for the grid, and another for the UPS output of the inverter. Both having their own separate neutral bars. The automatic transfer switches that I use will then switch the relevant circuits to either UPS Live+Neutral or Grid Live+Neutral.

Not sure why you do this ?

The hybrid inverter is bi directional so the power flows into the inverter and back out the inverter on the grid side. If the inverter goes into islanding mode and power is fed from the batteries, the solar panel could charge the batteries, but not feed back into the grid.

The only reason I would install a changeover/transfer/ bypass switch would be to feed power to the essential/UPS DB if the inverter had to be isolated from the system for maintenance or repair.

I am still trying to figue why a person would connect an earth leakage unit/RCB to the supply side of the inverter in SA ?

I cant wait to get the Sunsynk inverter so that I can start tinkering. I cant seem to find any 1C rated batteries at a reasonable price. Hubble and all their suppliers are out of stock. There is talk that Sunsynk have a 1 C battery being launched soon.

I would be interested to see your wiring configuration.

[recre8]

Not sure why you do this ?

The hybrid inverter is bi directional so the power flows into the inverter and back out the inverter on the grid side. If the inverter goes into islanding mode and power is fed from the batteries, the solar panel could charge the batteries, but not feed back into the grid.

The only reason I would install a changeover/transfer/ bypass switch would be to feed power to the essential/UPS DB if the inverter had to be isolated from the system for maintenance or repair.

Apologies if you know most of this already.
It depends on your usage I suppose. In my case, I want to have backup power if the grid goes down. So the transfer switch, switches my loads to the Sunsynk's UPS port. When the grid goes down, the Sunsynk doesn't push any power out of the GRID port so if you want to power anything during an outage, it has to be connected to the UPS port. BUT, this also means that when the grid is on, your loads are essentially being passed through the Sunsynk. And the Sunsynk 5kW I have is only rated for 35A current flowing through it. Given that on certains days where the dishwasher, washing machine and tumble dryer are running... switching on a kettle could exceed this. Hence the transfer switches. The transfer switches just allow me to swap the loads between pulling current through the inverter/having backup power OR pulling current directly from the DB. When the grid is on, and the inverter is feeding power through it's GRID port, the net result is the same.

I am still trying to figue why a person would connect an earth leakage unit/RCB to the supply side of the inverter in SA ?

The GRID port of the inverter should be connected BEFORE the EL/RCD. The UPS port of the inverter should have it's own EL/RCD.

I cant wait to get the Sunsynk inverter so that I can start tinkering. I cant seem to find any 1C rated batteries at a reasonable price. Hubble and all their suppliers are out of stock. There is talk that Sunsynk have a 1 C battery being launched soon.

I would be interested to see your wiring configuration.

Sure. Attached is the diagram from a year ago when I planned it. Might be a little unclear. DB_Export.pdfHaven't had any issues or nuisance trips whatsoever. I'm not an electrician or certified in anyway so use with caution. I just sent the diagram to a reputable electrician and had him come inspect after I did the job to get a CoC.

EDIT: PDF attached to post, but it doesn't seem to show. Here is a link.

[MarkN]

What I did with my Sunsynk/Deye inverter was to ignore the "island" output of the inverter you would normally use to power a relay to do the earth-neutral bond. Instead I installed a Hager 25A 1NO+1NC contactor in the DB. The contactor will close whenever grid power is lost and bond neutral to earth - and obviously when power restored, the contactor will open and break the bond. No particular reason other than it being neater in my opinion having it in the DB vs having it in the inverter cubby. Another reason I prefer doing it this way: The contactor will open immediately when grid power is restored whereas with the inverter, it will keep the relay powered (and thus the bond) until it synchronizes with the grid. By default configuration that is 60 seconds.

As for my earth leakage. I have two earth leakages. One for the grid, and another for the UPS output of the inverter. Both having their own separate neutral bars. The automatic transfer switches that I use will then switch the relevant circuits to either UPS Live+Neutral or Grid Live+Neutral.

The inverter decides when to switch between grid and UPS (island mode). You will have a floating neutral when the main power returns and the inverter waits for a stable grid supply before switching back out of island mode. This is why you MUST user the ATS on the inverter to control the earth/neutral bond. You can still have the contactor in the DB and run the control coil cables from the ATS in the inverter to the DB. As a failsafe, I do both, using two separate contactors, one contactor with two NC on the mains and another contactor with two NO on the inverter ATS (Signal Island Mode). The reason for the two NC and two NO is that I use the second NO/NC on each contactor to link to an indicator LED to indicate that the earth/neutral bond is in effect. The indicator supply comes from the LOAD (UPS) of the inverter.

[Justloadit]

The inverter decides when to switch between grid and UPS (island mode). You will have a floating neutral when the main power returns and the inverter waits for a stable grid supply before switching back out of island mode. This is why you MUST user the ATS on the inverter to control the earth/neutral bond. You can still have the contactor in the DB and run the control coil cables from the ATS in the inverter to the DB. As a failsafe, I do both, using two separate contactors, one contactor with two NC on the mains and another contactor with two NO on the inverter ATS (Signal Island Mode). The reason for the two NC and two NO is that I use the second NO/NC on each contactor to link to an indicator LED to indicate that the earth/neutral bond is in effect. The indicator supply comes from the LOAD (UPS) of the inverter.

I found that the delay between states is still long enough to trip my ELU when the inverter switches onto the grid. How did you over come this.