3 phase supply, single phase inverter

[Dylboy]

Hello

With regards to a 3 phase house how does one go about installing an inverter which is single phase...

I may be quoting a job for solar but competing against a quote for a single phase inverter and now wondering how does one do it.

Do you make the whole house single phase ?

If using the Sunsynk the excess solar feeds back to the non essential laods. But if those laods are on another phase then you can't.

So do you make the whole house single phase ? If so what about the meter for when you on the grid and it's only pulling from one phase ?



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[Andrew_van_Zyl]

Also keen to know.
When I installed my gennie I bridged the 3 phases in the switchover box so the single phase gen supplies all 3 phases

[Justloadit]

I changed my house from 3 phase to single phase. There was no advantageous reason to maintain the three phase. Made the genny and inverter easier and cheaper to install, and take advantage of the back feed.

[Dylboy]

Ah nice.

I think all is fine to make it single phase. But only thing back of mind is the billing and phase balance of Eskom and there may be penalty fees for doing so.

But if it's been done and no adverse effects of that sort then I think all fine.


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[Derlyn]

@justloadit. Evening brother.
Wracking my coconut 😁😁

Please explain to this sparky what you mean by taking advantage of the backfeed.

Thanks .. Derek

[Justloadit]

@justloadit. Evening brother.
Wracking my coconut 😁😁

Please explain to this sparky what you mean by taking advantage of the backfeed.

Thanks .. Derek

Hi Derek,

If you use the Sunsync or the Deye, and you rewire your DB into essential and non essential loads, where essential loads are fed through the inverter, then during the day if there is excess solar energy, that means that the batteries are fully charged, and the essential loads are drawing less energy than than is available from solar, then using the installed CT just after the DB incoming isolator, the inverter then feeds the excess available energy back into the non essential loads to reduce the energy from the grid to almost null if there is an over supply of solar energy..

Its almost like having the inverter on the input of the DB, but not requiring to size the inverter for the full DB load.
I think this is called backfeed.

[Derlyn]

@Justloadit
Thanks brother. Neat. So the more panels you have, the better, always.

I'm having loads of fun with my teeny weeny setup. This weekend I'm installing 3 analogue ammeters. Amps from panels. Charging amps to batteries. Load amps.

This will help me understand what is happening in real time without me having to guess.

Cheers.

[Justloadit]

@Justloadit
Thanks brother. Neat. So the more panels you have, the better, always.

I'm having loads of fun with my teeny weeny setup. This weekend I'm installing 3 analogue ammeters. Amps from panels. Charging amps to batteries. Load amps.

This will help me understand what is happening in real time without me having to guess.

Cheers.

Get these Digital Panel Meters from Mantech, I believe they are now in Port Elizabeth.
Go for the ones with an external shunt, and the shunt direction can be for charge current, and load current.
Just take note, there is a bad design here, do not switch the meters on with out the Shunt connected, else it damages the current measurement circuit.
They can go up to 30V DC direct.
In the case that you need higher voltages, and you are not scared to add a few capacitors to a module, then you can use this SMPS Module to do the meter supply directly off your source, alternatively you can use a small AC to DC PSU.

[GCE]

Hi Derek,

If you use the Sunsync or the Deye, and you rewire your DB into essential and non essential loads, where essential loads are fed through the inverter, then during the day if there is excess solar energy, that means that the batteries are fully charged, and the essential loads are drawing less energy than than is available from solar, then using the installed CT just after the DB incoming isolator, the inverter then feeds the excess available energy back into the non essential loads to reduce the energy from the grid to almost null if there is an over supply of solar energy..

Its almost like having the inverter on the input of the DB, but not requiring to size the inverter for the full DB load.
I think this is called backfeed.

Well explained explanation of the use on a true Hybrid - Going to steal it to use

[Isetech]

Just be aware of the inverter full feedback load capability of the inverter. If I recall an 8 KVA can feedback a max of 12KVA. This is where the supply(input/mains) wiring calculations to the inverter is important.

The way I understand it works, if you install a 8000 watt unit (around 35 amps) then the unit can feedback around 12000 watts (50 amps)

If you install a 4 or 6 mm wire you are going to experience overheating on the cabling. You would need to install at least 10 mm wiring to the inverter input.

The output/UPS/essential or whatever you wan to call it, will only require a 6 mm wire.

Talking Sunsynk, you then have the aux terminal which can be assigned to be used as an output or generator connection.

I cant wait to get my demo so I can start tinkering.

[Isetech]

Feedback or max continuous pass through current as it is referred to for a 5 KVA unit is 35 amps. It would be advisable to use a min. of 6 mm wire.

As per the spec sheet, an 8000watt unit standard output current is around 35 amp and the max pass through current is 50 amp, best you dont install anything less than 10 mm.

[Dylboy]

Feedback is not the same as let through.

Feedback is just what the excess PV does. Where it goes to the non essential circuits.

Let through allows for the 5kw to use up to 5kw of PV and battery and then an additional 3kw from the Grid.

So you can run more than the 5kw on the essential circuits.

This can look like the hairdryer, washing machines, vacume can run which is greater than the 5kw but the inverter now won't shut down (if grid is available) to supplement the extra load.

I must say that is how I understand it and tell clients. If I have it wrong please let me know

I have done only 1 Sunsynk so I am by no means expert haha


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[Isetech]

I am still trying to figure this out, feedback and pass through.

Feed back is controlled by the CT coil from the solar panels back to the non essential or grid side of the inverter or to export back to the grid.

Pass through is the current that can be supplied to the essential load via the UPS/essential side , ie: an 8 kw can handle 12 kw.

Still a bit sketchy with this information.

[Dylboy]

Yes that's how I have it too

It's nice as the cheap inverters the moment 5kw is on pulled the thing shuts down.

Also some houses not possible to rewire circuits to take the dishwasher, washing machine off the essential circuits as it powers the internet for example so the pass through is great as then they can still run when there is grid.

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[Isetech]

Which brings me to selecting the inverter size, why are customer offering 5 kva units used a a backup can only run at a small percentage of the available power.

The same problem we have when connecting a 5 KVA or smaller generator to a main DB.