Scenario: My PV is up and running, the battery has plenty in it, grid goes down (this has happened twice this week and it's only Wednesday). At present the out buildings are on the non-essential side. What's in there? Well the laundry, a second geyser (I keep this off), and the pool has it's own little DB fed from the out buildings. When there's no grid I can run an extension lead to the washing machine, but unless I do evil things I can't get power to the pool pump. Which annoys me because most days the system does support the pool pump with no problems.

Currently I have a change over switch so that I can run the essential loads off of grid instead of the inverter. This is in a local DB for the inverter. I attach part of the circuit diagram for my system,

So what I would like is a second change over switch so that I can switch the non-essential loads onto the inverter when we have no grid. I have to manage loads in this situation. I understand that. Most of the time we will be OK. This would also allow me to check how close I am to not needing a grid connection at all.

Obviously it would need to be a 3-way switch as is currently there for the backed up loads, with the middle position being off. I think there may be a way to render myself connection less depending on the positions of these two switches, but, again, this is for me to manage and I don't think anybody's going to get killed.

Is this a thing that can be done? Ultimately I might want to make this a smart solution with one of those CBI power indicators. But then again maybe I don't. Maybe manual control is better in some ways.

Edited January 21Jan 21 by Bobster.
add 2nd geyser to sub-DB

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Edited January 25Jan 25 by abd7

We have multiple changeovers in our DB board. 3 x Aircons, pool pump and irrigation pump. Allows us to have control over what runs on what, and especially if we have someone house-sit, then we can put all of them on Grid so there's no risk of them overloading the inverter. We know what we can/can't run together, but someone house-sitting would not.

Also useful for things like I prefer the pool pump to be on grid (hybrid inverter will still supply if there's enough solar), but during extended loadshedding periods it was nice to be able to switch it over for a day when the sun was shining so the pool wouldn't go green.

Some electricians/solar-installers are funny about it, had more than 1 argue with me "but you don't need one, just pick grid or solar and stick with it". And one who outright told me "I refuse to install a changeover because you don't need one". He obviously didn't get any work from me. But most are more than happy to install changeover switches.

@Bobster. Have you thought of getting a bigger inverter? It sounds like (from other posts also) that it is causing quite an inconvenience for you. You could be saving more on electricity and not have to worry about all of this load management stuff etc. And with COJ doing its funnies now with postpaid etc, seems the main thing stopping you going off-grid if you want is the inverter.

A luxpower 14kW is just undeer 20k. A ECCO 11kW is about 9.5k. It might be worthwhile to just upgrade and not worry about all this changeover switches, watching your loads etc.

2 hours ago, Denns said:

Have you thought of getting a bigger inverter? It sounds like (from other posts also) that it is causing quite an inconvenience for you

Indeed I have. But I'm stuck with it now. 10K seems like a stretch for me at the moment. But apart from that lawn mower, the 20 amp limit is not a problem for us.

I would agree that these days nobody should install an inverter rated at less than 8 kW. I got this one in 2019. The installer offered me a choice between the Goodwe and a similarly rated Victron. I knew very little about solar then and followed his advice. These days, with the benefit of what I now know and the equipment that is now available, I would make different choices.

1 hour ago, Bobster. said:

I would agree that these days nobody should install an inverter rated at less than 8 kW

8kW Sunsynk inverter with minimum 10kWh battery, then I would put the non-essential loads on the smart load output and set it to trip with grid. One could then change the setting and manage loads with an outage.

On 2026/01/21 at 11:01 AM, Bobster. said:

Currently I have a change over switch so that I can run the essential loads off of grid instead of the inverter. This is in a local DB for the inverter. I attach part of the circuit diagram for my system,

Fair enough the essential loads switch is pretty standard in all inverter installation and is actually meant as a bypass switch when your inverter goes offline( damaged, servicing) so that you are not stuck with no power on your essential loads side. But surely can be used at your discretion whether you want to use the inverter or utility feed.

On 2026/01/21 at 11:01 AM, Bobster. said:

So what I would like is a second change over switch so that I can switch the non-essential loads onto the inverter when we have no grid

This is where the plot thickens and where you need to be very careful.
The moment you start using two manual bypass switches to move loads between Eskom (utility input) and the inverter output across two different DBs, you introduce a serious risk.
If the switching sequence is wrong, you can unintentionally create a back-feed path from Eskom straight into the inverter output. That’s exactly why essential and non-essential DBs are normally isolated in the first place.
Here’s the risk explained simply:
Your essential DB bypass switch normally sits in inverter mode
(inverter feeds the loads, Eskom isolated).
You only flip it to Eskom when servicing the inverter or forcing utility takeover.
Now you add a second manual bypass on the non-essential DB between Eskom and inverter output. If you unknowingly leave essential DB bypass on Eskom, and
Non-essential DB switched to inverter output you’ve just created a direct path from Eskom into the inverter output. That’s how inverters get destroyed.
There are only TWO safe and viable options:
1. Move the required loads from the non-essential DB to the essential DB
Simple, safe, no extra switching logic, no risk of back-feed.
2. Keep the essential DB bypass as-is and use an AUTOMATIC transfer switch (ATS) on the non-essential DB Eskom is wired as primary. Inverter output as secondary
The ATS only changes over when Eskom fails. No possible feedback path between inverter input and output
Important:
Your inverter must be capable of carrying the full connected load in inverter mode when Eskom drops.

Edited January 23Jan 23 by TaliaB
Spelling and grammar

21 hours ago, TaliaB said:

The moment you start using two manual bypass switches to move loads between Eskom (utility input) and the inverter output across two different DBs, you introduce a serious risk.
If the switching sequence is wrong, you can unintentionally create a back-feed path from Eskom straight into the inverter output. That’s exactly why essential and non-essential DBs are normally isolated in the first place.

OK. This is the sort of scenario I was concerned about. And I think this COULD happen. Eish...

21 hours ago, TaliaB said:

1. Move the required loads from the non-essential DB to the essential DB
Simple, safe, no extra switching logic, no risk of back-feed.
2. Keep the essential DB bypass as-is and use an AUTOMATIC transfer switch (ATS) on the non-essential DB Eskom is wired as primary. Inverter output as secondary
The ATS only changes over when Eskom fails. No possible feedback path between inverter input and output

Part of why I'm thinking about this is that it becomes a test to see if I can go off grid. If I find I can't then I can back out and throw that switch. I also would like to be able to run the pool pump off of solar when the grid is down.

But I'm starting to think this is a fool's errand, especially with a 20A inverter. Let's say I get the switch wired in and I don't blow anything up. Let's say I get one of these 1500 W lawn mowers I saw at Builders this morning. Oh wow! I'm off grid.

Then I get guys in to work on my house and they plug in who knows what appliances and now I have to find out the hard way if that gear will overload the system or not. OK... I'm thinking this is unlikely with hand held tools, but all I can do, really, is reduce the chances of an overload, I can never eliminate it. Even with a plain old grid connection you can't 100% rule it out, but it's 60A and so the chances are vanishingly small. But I will have 20A...

RE that ATS, does it have a manual override? Could somebody just throw the switch?

Talking of the out buildings, they have their own sub DB. The plug circuit on that DB has a 20A breaker. That doesn't trip, but I'm guessing that the breakers will tolerate a short overload.

17 minutes ago, Bobster. said:

OK. This is the sort of scenario I was concerned about. And I think this COULD happen. Eish...

Part of why I'm thinking about this is that it becomes a test to see if I can go off grid. If I find I can't then I can back out and throw that switch. I also would like to be able to run the pool pump off of solar when the grid is down.

But I'm starting to think this is a fool's errand, especially with a 20A inverter. Let's say I get the switch wired in and I don't blow anything up. Let's say I get one of these 1500 W lawn mowers I saw at Builders this morning. Oh wow! I'm off grid.

Then I get guys in to work on my house and they plug in who knows what appliances and now I have to find out the hard way if that gear will overload the system or not. OK... I'm thinking this is unlikely with hand held tools, but all I can do, really, is reduce the chances of an overload, I can never eliminate it. Even with a plain old grid connection you can't 100% rule it out, but it's 60A and so the chances are vanishingly small. But I will have 20A...

RE that ATS, does it have a manual override? Could somebody just throw the switch?

Talking of the out buildings, they have their own sub DB. The plug circuit on that DB has a 20A breaker. That doesn't trip, but I'm guessing that the breakers will tolerate a short overload.

Interesting that you need that lawn mower. Not sure what my 1800W starts at but running below 800W once on speed. My 5kW Deye very happy even from battery.

16 minutes ago, Scorp007 said:

Interesting that you need that lawn mower. Not sure what my 1800W starts at but running below 800W once on speed. My 5kW Deye very happy even from battery.

Mine is supposed to be 2.5k, but on starting uo it will trip my inverter every time. This is the fly in my current ointment.

38 minutes ago, Bobster. said:

Mine is supposed to be 2.5k, but on starting uo it will trip my inverter every time. This is the fly in my current ointment.

Soft starter as per a previous post is your cheap solution.

8 hours ago, Scorp007 said:

Soft starter as per a previous post is your cheap solution.

A thin, long lead or a makeshift inductor could also limit startup current.