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Posted (edited)

A statement and a question.

Three phase power is not nesseccary for a regular household that is peaking at 4kwh on power use. (2 geysers, one pool pump and a regular oven).

Trying to put PV's into a three phase wired house is proving difficult for the following reasons:

  1. You have to install three singel phase inverters like (Growatt SPF5000ES)
  2. Buy a three phase inverter (a fair whack more expensive than its single phase compatriots)

One last opton could be to revert back to single phase for the house?

  1. Application at the municipality to rewire from streetbox into the house (cost?)
  2. DB changes in the house by a electrician and a COC

Some advice from the forum members that have run into this same problem would be appreciated.

LD

Edited by L_D
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Hi @L_D

I had a similar puzzle when I was looking at solar for my house as I had a 3 phase supply with a cottage and stables.  I have 4 x Geysers, a pool, a borehole and use about 40-50kw/hr a day which I run of my 8kw Sunsynk single phase inverter.  

My understanding is that a 3 phase inverter is essentially 3 x single phase inverters operating in sync to create 3-phase power. You cannot use 8kw on one phase on then 2kw & 2kw on the other 2 phases. If you load one of the phases with more than 4kw you will overload the inverter and it will trip out.

This is what makes balancing your loads on a 3-phase inverter a lot more important. 

 

My solution was to centralise all my loads on one phase to make things easier to manage and to get my 3 phase wired DB Board converted to single phase and only use one of the phases being supplied by Joburg City Power. 

As I have no 3 phase devices it was a very simple operation and took the electrician about 5 minutes to bridge the phases on the supply side. He did not need to "rewire" the DB Board at all. 

There is no need to notify the municipality that you are only using one phase unless you need to reduce your connection fee from the municipality. I am on pre-paid so there is no connection fee with COJ either way. 

If you do have any 3-phase motors etc you can usually find a VSD (variable speed drive) that will run your 3-phase motor from a single phase supply. 

 

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