Hello all,

New user checking in. The current state of Eskom and the stark reality of loadshedding for probably the next (let's be realistic here) decade has finally spurred me on to get something installed that will help us become a bit more independent from Eskom and keep the essentials running in the case of a total grid collapse (something I'm now taking serious as a likely outcome).

To keep costs low, I am going to do the installation myself, starting with a battery backup system, then adding on solar and/or a standby generator depending on how impending the level of doom is going to be at that time. I will probably create more posts about this as I go along this journey. I might not remain in this country for very long, depending on some developments at my employer. This means a R100k+ investment tacked on to my bond is out of the question. I want something small for lights and the fridges and now and then the TV, with enough battery capacity for stage 6-8-10, and then add to that a small (2-3kva) generator that's exclusively used to charge the batteries. This to be used only if we have proper extended darkness. Solar can then come after the emergency backup is in place, but that's a bonus.

My question for this thread, and the means of my introduction, is to try and find out if anyone can assist in giving me the high-level requirements for a COC. Like I said, my plan is to do the install myself, but then I want to get a COC of the install, to ensure my insurance and all that is happy. I don't want to cut corners with this stuff, and I want to do the wiring/install proper. I'm just not really willing to pay someone R100's per hour, when I am more than capable to do it myself.

I know you need some form of DC disconnect/fuse for both the battery bank and the solar (if present), but I'm unsure about the wiring into the existing DB board and this is where I would appreciate some assistance and guidance. I will have a crack at a diagram later today to share with you my thoughts and plans, and then we can see what the hivemind thinks of my plan, and where I need to make changes to remain compliant.

Thanks!

I'm pretty sure only a qualified electrician /professional are allowed to work on the db. 

That said I did mine myself and got an electrician to check it and give me a COC. 

You can still mount all panels, mount the Inverter and battery. Draw all cables between Inverter and panels. Make sure ac and dc cables are in separate trunking. 

Make sure on cable sizes between all elements and that they can handle the draw. 

There's also some rules on conduit size and how many cables are allowed in it. Something about compensation for heat if I remember correctly. 

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I'm pretty sure only a qualified electrician /professional are allowed to work on the db. 

I'm pretty sure of the same thing. But what are they gonna do - put me in jail? I'm more than capable of working on my own DB and I have done so in the past.

What I'm interested in learning is about the nuances of the COC requirement. I don't want to do an installation that conforms to my standards, only for an electrician to come and say I need to redo a bunch of things before I can get the COC. 

Your comment about conduit size is interesting to me. I've seen lots of talk about conduit on this forum. I've been in many roof spaces and I've never seen conduit there, except where the wiring enters the wall. Is conduit only a requirement for when the cables would be exposed otherwise, i.e. running from the ceiling down to where the inverter sits? Or must solar DC cables always run in a conduit, even when it's in the roof space?

What about disconnects/change-overs? Am I correct in assuming that the inverter must always have a change-over switch downstream of it's output?

If I bring a generator into the mix, will I have to have another changeover dedicated to the generator that sits upstream of the inverter's input?

If you know a sparky, get him to go over the design and installation plan with you, I did that and it helped a lot, I was missing a few things (yep the isolator / fuse between inverter and battery) and he highlighted it and made a few recommendations as to the MCB's and priority loads, once I done all the trunking and cables, I got him to do the connection to the mains, he happily issued COC based on his involvement.

Thanks, that seems to be the best route, and what I must do as well. Only problem is, I don't know any electricians haha. Let me plan my project a little further and see if I can track one down through my contacts.

As an aside, I've sometimes wondered what's the shortest procedure to become a certified electrician/plumber. Does it have to be a multi-year apprenticeship, or can I complete an online degree or something similar. Sometimes I fantasize how convenient it would be to just be your own electrician! 😂

I installed system myself and had an electrician COC it afterwards - hence take this advice from whence it comes

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Am I correct in assuming that the inverter must always have a change-over switch downstream of it's output?

Nope, to my knowledge it's not a requirement, but definitely a good to have. Let's you connect your backup loads direct to Eskom in case you need to do maintenance on the inverter, I've also enjoyed this change-over switch in times of troubleshooting and testing  (as a self-installer you're probably going to want to dig deeper into the "results" once it's all installed

Generator - not sure, but I suspect for sure you'd want / need to have a change-over switch installed. Depends though how you're looking to plug it into the inverter system - directly Line in (parallel to Eskom) or through the Aux Port of the Sunsynk or similar. (not sure what inverter you're looking to install)...

 

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... directly Line in (parallel to Eskom) or through the Aux Port of the Sunsynk or similar.

Parallel with Eskom for now. I don't have the budget for the expensive sunsynks, and will be looking at the cheaper Axperts or Must brand inverters. As far as I know they have no aux input. That means a changeover will probably be a requirement there, to ensure the genny does not backfeed into the grid. 

Yep then you'd need a change-over...

Beyond that:

• Battery fuses / disconnect between battery and inverter
• DC protection box (surge protection, fuses, potentially also a disconnect) between panels and inverter
• Two CB's between Inverter and DB (one line-in / non-essentials / Eskom side   ;   one line-out / essentials / backup loads).

Then you'd split the DB board according to your requirements - remember to separate the respective neutrals accordingly.

Suggest change-over on backup loads (so you can divert to Eskom, if needed, as described above). Plus generator change-over.

Make sure all is earthed properly, and earth leakage between inverter and backup loads (plus earth leakage between Eskom and non-essentials).

All cables obviously need to be specced correctly (and protected with appropriate CB's.

That's all that comes to mind right now - as said, I'm no expert, but the electrician, after careful analysis, was happy with my work and supplied CoC...

The requirement to conduit DC cable - good question, am following recommendations on this  (some time back on this forum many guys were saying one should (maybe even has to?) use steel conduit...

Thanks @markus_m2!

I'm not sure I follow your last bullet point regarding the additional CBs though. See my below block diagram. Do I need to put additional breakers before each of the sub sections of my DB: backup-loads and non-backup-loads?

see in red

to my understanding, every seperate cable needs a form of protection (i.e. circuit breaker)

Edited January 26, 20233 yr by markus_m2

So something like:

that's it...would appreciate someone more knowledgable to confirm though...

 

Thanks for the help! Would also appreciate a confirmation that this is at least correct from a COC perspective. 

Do I need a COC for a small inverter generator when I use an extension lead to power my fridge? I know you are not allowed to plug it directly into a 15A wall socket.