Hi all.

Disclaimer: I won't be doing this myself - I don't trust myself just yet - but I want to be intimately involved, and I'm planning up front to see how it goes. So, I'll give detailed plans to the installer I select, and hopefully they will be GOOD plans.

So, I think "Member Installations Showcase" is the best Forum for this project, and I'd appreciate your input and comments/advice as I go.

This project is the plant 3 I've been anticipating in my signature. The spec will emerge as I go.

My first Area of interest is regarding the wiring of the DBs and Inverter.

I've googled and searched this forum, and read various manuals (SunSynk Inverter manuals), and battled to find a complete wiring diagram for the AC from Grid to Inverter to home load. There are many references and diagrams. Most seem to be only parts of the picture, focusing on specific details. And since I am not an electrician, I'm not always certain that I'm reading them correctly.

So, from what I've read, I've drawn up my own diagram. I'd really appreciate your feedback on whether this is correct, accurate, safe and will achieve a CoC. Remember - I'm no electrician, so forgive my lack of use of all the "standard" circuit diagram symbols that may apply.

Context: I plan to use a SunSynk 5KW Inverter, so this diagram is intended for that use-case. For example, the correct use of the CT and the Earth-Neutral bond relay are both important in this scenario.

Here's the diagram: !!!Do not use this diagram - there are important improvements later in this thread!!!

 

Key Comments and Questions:

• I have an empty wall in my garage, roughly 2.5m wide, alongside the existing DB, that I can use for the installation.
• I plan to install the Main DB and Essential load DB as physically separate DB boxes, with the Inverter between them.
• I've used the Yellow/Blue colours for Live/Neutral after the inverter, just to make it very clear what is before and what is after the Inverter. I'm not sure if I can get the cables to do it that way in the actual installation in the house.
• Question: It seems to me that the Earthing for the Essential Load should be independent of the Earthing for the Main DB, except when bypassing the inverter. But I'm not certain if the way I've drawn this is correct? (Since there is an RCD on the Essential Load DB, perhaps the change-over switch need only be two-pole?)
• Question: Following on the Earthing question above - when the grid is dead (not an uncommon occurrence here in ZA), we must rely on the Essential Load DB's Neutral, and thus also the Earth-Neutral Bond. Have I got this right in the diagram?
• Question: You'll note that I'm uncertain about the amperages of various breakers, so your suggestions on these is welcome.
• Question: I'd like to be able to remotely switch some of the Load that is on the Main DB, to take advantage of excess production at the appropriate times. Any advice on what WiFi switches are respected for quality and reliability for CBs for things like the Geyser, Oven and Aircon. (Sonoff? Other?)

Looking forward to your comments and advice... 🙂

Edited February 4, 20233 yr by Patrick OReilly

Just 2 quick points before I sign off. The 25A to the inverter to be after the 63A main switch otherwise you have to work on a live circuit on the transfer switch. 

2nd point the earth does not get switched/interrupted by any form of switching(transfer) 

I will look at the rest later. 

Edited February 4, 20233 yr by Scorp007

Thanks @Scorp007.

24 minutes ago, Scorp007 said:

The 25A to the inverter to be after the 63A main switch otherwise you have to work on a live circuit on the transfer switch.

I was wondering about this - I've seen different diagrams where the Inverter is fed either before or after the MCB, and so I was unsure.  But your point makes sense.

Now, there is another breaker on the property where the power enters the building, but before it comes to the DB. I did not show this on my diagram (of course I should have... 🙄 It should be shown between grid and the CT) This essentially means the CB for the inverter sits between two other CBs. Would it then be advantageous to leave it where it is? It would allow for a scenario where something trips the Main DB MSCB without tripping the feed to the Inverter.

29 minutes ago, Scorp007 said:

the earth does not get switched/interrupted by any form of switching(transfer)

Ah!!!! That is very sensible the moment you say it out loud. So, the change-over switch should be just 2-poles (Live & Neutral). This leads to a question: Should the earth bars in the Main DB and the Essential Load DB be directly linked to each other?   I've seen diagrams drawn both ways, so I don't know which is correct!

PS: I'm busy editing v2 of the diagram to reflect your advice...  Thank you!

I've also noticed some other diagrams have Surge Protection Devices (SPD) included. And there seems to be some debate about exactly where they should be, and whether they should have CBs in front of them too.

Any advice on this for me?

5 hours ago, Patrick OReilly said:

I've also noticed some other diagrams have Surge Protection Devices (SPD) included. And there seems to be some debate about exactly where they should be, and whether they should have CBs in front of them too.

Any advice on this for me?

Yes SPD MUST be included. Yes the practise is a disconnect device based on current is used in front of them in order to break the circuit and try and remove the surge. It may be fuses as well. 

Transfer switches are in 2 pole and 4 pole. 1ph and 3 ph.

22 hours ago, Patrick OReilly said:

 

• I've used the Yellow/Blue colours for Live/Neutral after the inverter, just to make it very clear what is before and what is after the Inverter. I'm not sure if I can get the cables to do it that way in the actual installation in the house.

Members that are more up to date than me please correct my statement.

Decades ago the regulations indicated that neutrals have to be black and all earth wires bare or green/yellow. If it still holds your orange and blue will not be allowed.

There are many different smart switches that should be good enough to switch some loads from a remote location via the phone APP.

1 hour ago, Scorp007 said:

Members that are more up to date than me please correct my statement.

Decades ago the regulations indicated that neutrals have to be black and all earth wires bare or green/yellow. If it still holds your orange and blue will not be allowed.

Thanks @Scorp007.  My diagram uses an orange shade as the yellow does not show up well on a white background.  Anyway, I'm not too hung up on using blue/yellow cables for the installation - it was more of a passing thought. I certainly don't want to have regulatory issues after the fact!!! 🙄

I found this good topic elsewhere on the forum: Advice on wiring Sunsynk 5kW (powerforum.co.za)

From there I've tried to edit my own diagram - specifically for the Surge Protection Devices. I'll post my new diagram shortly.