3 phase supply, single phase inverter

**Dylboy** · 30-Jun-22, 02:18 PM

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** · 30-Jun-22, 05:44 PM

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** · 30-Jun-22, 07:56 PM

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.

**Isetech** · 01-Jul-22, 09:09 PM

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** · 30-Jun-22, 08:56 PM

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** · 30-Jun-22, 10:13 PM

@justloadit. Evening brother.
Wracking my coconut 😁😁

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

Thanks .. Derek

**Justloadit** · 01-Jul-22, 07:36 AM

Originally Posted by Derlyn

@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.

**GCE** · 01-Jul-22, 10:59 AM

Originally Posted by Justloadit

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** · 02-Jul-22, 06:31 AM

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.

**Derlyn** · 01-Jul-22, 09:51 AM

@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.