Neutral/earth bond for inverters

[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.

[Dylboy]

Hey man

So the bi directional is only when there is excess is solar..

So there are three ports.
Grid
Aux
Load

The load is where you connect your essential items.

Aux can be for genny input or other circuits that you want a small amount on essential but there is then a battery limit to when that circuit can be used. I.e between 60 and 70% then it can be used.

The grid is there you connect the feed Into from the DB, then when there is excess solar and batteries are full it then feeds back on that circuit to go to your non essential loads but does not back feed as the CT coil is installed as a goal keeper to stop it going past him.

When island mode is initiated as Eskom is off then the inverter will not feed any excess back on the Grid feed even if there is excess however your Load (essential circuits) will have access to the solar and batteries and also the Aux port.

Sorry if you knew all this but I am not 100% sure so figured just to type it in case

Sent from my CPH2197 using Tapatalk

[GCE]

Hey man

So the bi directional is only when there is excess is solar..

Can the Sunsynk use batteries to feed back into the grid ?

[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.

[Dylboy]

The sunsynk has a let through of an extra 5kw as well, so you not limited to the 5kw but it can pass through 10kw.

So 5kw via panels and batteries and then can pull extra 5kw from grid to power the loads too.


And the battery does not feed to grid, only to the load port i.e the essential circuit.

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[Isetech]

The sunsynk has a let through of an extra 5kw as well, so you not limited to the 5kw but it can pass through 10kw.

So 5kw via panels and batteries and then can pull extra 5kw from grid to power the loads too.


And the battery does not feed to grid, only to the load port i.e the essential circuit.

Sent from my CPH2197 using Tapatalk

I havent collected the Sunsynk yet so I am still in the research phase of the inverter, the money has been allocated, but I am waiting for a response to see if and when the the 1C Sunsynk battery will be launched. Hubble is out of stock and on back order. Lets hope Sunsynk pull finger and get the 1C battery out in the market sooner than later. I have sourced a really good price, so I have a few others interested, just waiting for payments. I am hoping with an order of couple hundred K, I can negotiate an even better price and include the delivery cost.

This inverter/battery/solar is huge turnover for anyone venturing down this road, I have noticed everyone, including the electrical wholesalers, the man on the street, the shop on the street corner, you name it everyone is an expert and selling systems.

[Dylboy]

That is cool a 1C battery ! That would allow a kettle to be boiled hahaha.

Will look into the sunsynk one, didn't know did 1C. Thanks for sharing that !

I see installs often now too all sorts of standards and the clients have zero idea about their system actually and for now it's working but not for long.

These okes selling lead acid batteries in a box saying all sorts are just going to make angry customers in a year but hey they just don't answer the phone when that client calls...

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[GCE]

The sunsynk has a let through of an extra 5kw as well, so you not limited to the 5kw but it can pass through 10kw.

So 5kw via panels and batteries and then can pull extra 5kw from grid to power the loads too.


And the battery does not feed to grid, only to the load port i.e the essential circuit.

Sent from my CPH2197 using Tapatalk

This is where I have a different opinion on how hybrid systems should work.

I believe that a hybrid should be able to feed excess solar and a portion of battery back to the grid

That the backup output terminals should not be loaded to heavily just enough to take the headache out of loadshedding and that that the majority of the battery is used to store excess solar and then feed back into the house grid at night to reduce electricity .

That way you are maximizing your solar and battery storage.

For example - we installed a 5kw hybrid with 7Kwh of battery storage and 4 kw of PV.

The unit is set to retain 30% of battery for grid outage.

We start the morning off with only 30% of battery - solar feeds backup output first ( lights and a couple of plugs) , then house grid and then charge batteries - If it is washing day the wash machine uses the excess solar not used on backup and supplements or nullifies the grid usage.
When the house grid is not using all excess solar then it goes to batteries
Generally batteries are charged by around 13H00 sometimes 15h00

As the sun sets and there is insufficient solar to feed house hold appliances on the house grid and backup output the batteries start supplementing the grid feed .

On this particular install the batteries almost nullify grid usage until 22H30 at night , other nights till 2 in the morning depending on how much cooking etc happens.

Once the battery reaches 30% it stays there until a grid outage - Next morning same story .

You can adjust battery reserve if it looks like a rainy day or excessive loadshedding .

PE is on time of use for PV installs so we get him over the peak demand time period and it helps to pay back his investment. We also do not run the risk of overloading the backup output

On this install we cut his electricity bill by 60 to 70%

Have another one with 14Kwh battery and 5,5Kw of PV and cut electricity by 90%

[Dylboy]

Hey GCE, look I double guessing my self now as I think there is a setting for battery to also back feed to grid and non essential circuits.

Basically you set parameters to what battery state you want at what time and it uses what ever battery and solar available before going to grid.

I have set up the clients similar to what you said so they have savings and also battery for load shedding. Albeit more than 30% in there case.


Had a rough start this morning and may have spoken some k@k before.

Need to try see what I set it up as but he has already a 50% saving and runs pool pump and a heat pump hahaha.

Sent from my CPH2197 using Tapatalk

[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.

[Isetech]

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.

Apparently Sunsynk are aware of the problem and are busy updating the firmware.

My concern is what if the contactors fails, we all know how contactors fail. Have measure been put into place to identify and shutdown the system if the contactor fails.

[MarkN]

Apparently Sunsynk are aware of the problem and are busy updating the firmware.

My concern is what if the contactors fails, we all know how contactors fail. Have measure been put into place to identify and shutdown the system if the contactor fails.

The contractor is a NC contractor, so the most likely failure is coil failure, which will cause the contractor to fail to NC, which will trip the supply earth leakage:

[Thys LOW Elektries]

The problem with the Sunsynk is that you must read the manual before attempting to install and wire it. The inverter uses the mains input as an output for normal power. A second port is uses for essential loads and a third port for generator or windmill. Mess with the wiring and you will be surprise what can happens, oh yeah I forgot about the all important Ct that must be connected to the mains