Hello everyone,

I am putting together a home off-grid style system (first time doing so), and have had endless "issues" with trying to have a professional install a system in any reasonable length of time or price.
I seem to think I have a reasonable understanding of electrical theory, and enough common sense to write this post instead of simply trying things Russian style and hope they don't blow up.

When asking technical question of professional installers who should know these things, I end up with blank stares which doesn't exactly instill a sense of confidence in me. At this point I want to know exactly what the correct configuration is supposed to be, and simply have my normal electrician inspect and sign off the build.

Primarily I am having a hard time trying to find the simplest, yet safe way to setup the Earth/Neutral bonding so that I do not get a residual charge build up when Eishkom is loadshedding, which then causes the earth leakage to trip as soon as the mains in power is restored.
The system is not yet installed, but I have had to deal with other systems that have this problem and don't want that headache at home.
I am specifically trying to avoid using an earth bonding relay if possible, and at this point in time I have read so many conflicting opinions, that I am now thoroughly confused 😛

I do know (if it is even accurate) that the primary municipal earth/neutral bond is at the transformer, and that you are not allowed to rely on this bond for your house, and that a separate earth spike needs to be bonded in your main DB to ground your system. I do not know where and how the primary earth/neutral bond is done in the main DB.

 

The system is as follows:

1x Victron MultiPlus-II 48/5000
1x Victron SmartSolar MPPT 150/60
1x Victron Cerbo GX
1x Victron Lynx Distributor
2x Hubble AM2 Batteries
6x CA605W Panels

Preliminary DB Configuration: Main DB + Sub DB

Main DB
a. Direct Utility supply on Mains breaker -> Earth Leakage -> Inverter breaker. (possibly oven & Geyser as well)
b. All other house circuits fed from off-grid Sub DB

Sub DB
2 Pole, 3 position Selector -> Utility side supply bonds neutral bar to Main DB neutral bar & live to Main breaker out.
2 Pole, 3 position Selector -> Off-grid side supply bonds neutral bar to inverter neutral out & live to inverter live out.
2 x Lights breaker (before earth leakage)
Earth Leakage -> All other house circuits.

Question 1: I am assuming the main DB earth leakage is still required because it is powering the inverter AC input which needs protection.

Question 2: Is the selector configuration correct, or am I missing something on how the neutrals are connected in either position.

Question 3: Where do I bond the damn earth connections? I can simply bond the Sub DB earth to the Main DB earth in a permanent connection?
This is where I fall short trying to figure out where, or if I need to bond earth/neutral to prevent residual charge build up. I do not know if the inverter has an auto/permanent earth/neutral bond, or if a fixed earth/neutral bond will cause a problem when the utility power is down or when it returns.

Answer: Victron have an internal relay that bonds the inverter output neutral to the chassis earth when the AC input relays are opened. No external bonding needed, but chassis earth MUST be connected correctly.

 

Any insight would be appreciated, so that I can avoid endless call out fee's trying to reconfigure the system over and over again.

 

Thanks

~Scarlock

 

 

Edited January 31, 20232 yr by Scarlock
New Info Found

Hey @Scarlock

 

The setup I'm busy with is very similar to yours, with to-a-T the same equipment.

My setup however is slightly different, I have mains going into a Changeover switch (eskom/gennie).

I want to change it so that it goes ESKOM/Gennie Changeover > PV connected Multiplus II > House DB.

Did you ever get answers to your questions?

Below is the changeover, what's additional here, is SPD's and a time-delay/AVR controlling a contactor, from the contactor it goes to the Main DB, right behind this wallbox. So I want to change it that goes from the contactor, to the PV connected inverter, and then back to the mains db...