Jaws

When it comes to cables, bigger is always better. But in this case 2.5mm2 would be suffiecent. To understand why you first need to understand why we earth equipment. And earth conductor provides a low impedance path for fault current to flow back to the source. The path back to the source`s impedance has to be low because the fault current needs to be sufficiently large enough for the overcurrent device on that circuit to pick up the fault and interrupt it. So in most cases the conservative approach would be to size the earth conductor the same as a phase conductor. But there in your case there is no source, or lets rather say you are not earthing the batteries to protect you from a battery voltage shock. Rather what you are doing is, is that you are bonding the batteries and cabinet to earth. All extraneous metal must be equipotential bonded to earth. Bonding ensures that two metal bodies that are bonded will be at the same electrical potential. That means there will not be an electricity building up on one piece of equipment or between two different pieces of equipment. No current flow can take place between two metal bodies because they have the same potential. Also if somehow (and extremely unlikely in this case) a live AC wire gets into contact with the metals case, or metal battery case you won’t get shocked if you should touch it, as the metal will be a the same potential as your body standing on the ground. The 6 mm2 minimum requirement comes form :

Rumor has that certain members sitting on the committee is pushing for this never to see the light of day and to simply adopt IEC as has been the case with most other SANS. We can only hope.... Same for SANS 10142-1-2 why go write something for South Africa if its already available

If the moderators feels that this in inappropriate please delete this thread. _______________________-- So a good friend of mines is a journalist for an Afrikaans womans magazine. He was asked to do an article on the South African Power crisis. He basically sent me 5 questions (Translated from Afrikaans) 1) How would you recommend the article must be written 2) Does is make sense to invest in alternative energy sources like solar water heaters, generators and solar PV panels 3) Is alternative energy not very expensive and would it be affordable for the average household to invest in a system now. 4) What advice can you give to the average household to save energy ( With a few practical examples) 5) Anything else to add. He also wants to add my Name and credentials and company name to the article to give some credibility. So this is where the forums comes in. I would like to rather just use my name and professional qualifications and then member of Powerforum.co.za (and maybe even the members name with the most likes on his response) instead of the company I work for. The reason being that I do work for a certain state entity which could potentially be negatively influenced by the article I have already prepared answers to her questions, but I thought that if I open it to the forum members the quality of the article will increase and with the moderators blessing seeing the forum address will have those interested coming over here for more info. She didn’t want to go to a Solar installers as this would obviously bias the article. Keeping the audience in mind actually made this a bit harder. This cannot get to technical, I tried formulating the answers as if I would be explaining it to my 60 year old mother.

Stoic rather spend a R1.5k now and get an energy meter installed something like this would be more than sufficient for what you need: https://www.builders.co.za/Electrical/Inverters-%26-Solar-Energy/Solar-Accessories/Efergy-Energy-Meter-E2/p/000000000000492466?gclid=CjwKCAiA_P3jBRAqEiwAZyWWaJLmYhsgdzT5b2X-OFlbUEi1L-x2PSK9ifJZ6CrotOAjnBaGg6j1BhoC50YQAvD_BwE After a week or two send us the trends from the meter. Then we will be able to more accurately predict how many battery capacity is required.

Very good point for the Cape Town guys ....... 🙂 For the OP - Although the Goodwe is capable of exporting to the Grid, at this stage it would be better to configure the inverter not to.

Inverter: For someone with grid access I wouldn’t recommend the Axpert. Rather look at Hybrid inverters like the Goodwe or similiar. The additional R13k in capital over the Axpert will be recouped. The installation is also actually simpler with a Hybrid inverter and you will be able to maximize the energy generated by the solar panels. Read the manuals for the Goodwe from here :https://thepowerstore.co.za/collections/inverters/products/goodwe-em-5kw-hybrid-inverter-2-3kw-backup Let me know if the advantages between the Axpert and Goodwe is not evident. Your consumption is low so you will probably get away with a smaller unit than the 5 kW, but the price difference between them does not really warrant going smaller. Battery: Pylontec or similiar is the way to go for systems that are planned to run for 10 years or longer. __________________________________________ A while ago I spotted a system advertised and in my opinion the way to go for now: https://solaradvice.co.za/product/lithium-storage-3-92kwh-solar-power-kit/?utm_source=Click&utm_medium=Channel&utm_campaign=Google_ZA&SFDRREF=SFDR_299055705&ptcid=9226_617_401969991&gclid=CjwKCAiA2fjjBRAjEiwAuewS_WZfe2cU-maUpMcfhq-XfmKtQ1nQlGiIVHdNYvoDfCfQvCPblFAUvBoCyuEQAvD_BwE

The earth fault return path is there to conduct the phase to earth fault back to the source of supply. When you have grid power your source of supply is the minisubstation, hence why the starpoint of the secondary winding is bonded to earth. When you are in UPS / Inverter mode and disconnected from the grid the minisub is not your source of supply anymore, your inverter is. So in a phase to earth fault the fault current will only flow back to the inverter and not back to the minisubstation. The earth leakage device installed at the inverter supply will protect you here.

Grounding , Earthing, Bonding If only I had some free time

But for Pilotfish solution to work correctly you require a change over switch

On site we will cut open a crimped stranded cable, when you look into the crimped cable the stranded cable must look a like solid copper cable, then you know the contractor is using the correct equipment.

\\OFFTOPIC Earthing of DC system. Fun topic this. At coal fired steam turbine power stations there are massive DC backup systems in place for the turbine and draft fans, mainly to provide oil for the bearings. Ill see if I can remember to bring my backup-drive to work I have a few cool photos. Fans are in the 6 MW to 12 MW range, turbine drives a 950 MW generator. In any case these motors are 220 V DC, they only run for the time it takes the backup generators to start up and for the AC pumps to take over again. The DC motors make us of resistor starters as soft starters. Here we connected a few 1.2 V batteries in series, and we connect the center point to an earth monitor. So if you measure from earth to Plus you measure + 110 VDC and from earth to negative - 110 VDC, between plus and minus obviously you get the full 220 VDC. If someone should make accidental contact with the plus wire he will only be zapped by 110 VDC and not 220 VDC, but now the negative is also “live”. The system is such that plus or minus can touch earth without the system tripping but an alarm will be activated. Also on process control system using PLC`s or a DCS we use 24 VDC or 48 VDC the grounding of the negative is always a hot topic, due to floating negatives and ground loops. \\BACKONTOPIC

All my single line diagrams are always power flow / current flow top down, this one messes with my OCD 🤒

Where are you located ? As the company I work for we have two Elspec G4500 Power Quality analyzers, https://www.elspec-ltd.com/elspec-shop/power-quality-analyzer/portable-power-quality-analyzer/g4500-portable-power-quality-analyzer/ you can rent one from http://www.impactpower.co.za/eform/submit/contact-us but you needs some know how to operate them and interpret the results. They will also come out and do the analyses and specify the correct Harmonic filters. For a residence this might be cost prohibitive

How does City of Cape Town define : 1.Grid-tie 2.Grid connected 3.Hybrid

What's the cable distance/length How will the cable be installed What type of cable will you use

Victron is proper kit. But you do pay for the privelage. I have mate that does solar installations. He currently has 3 teams each doing a residential install per day. He is fully booked for weeks in advance. He only installs Goodwe inverters with Polyntech batteries. Good bang for buck with minimal comebacks to date. The quality of install and how you use it also plays a factor, not just the colour of the kit hanging on the garage wall.

Very good post Power Punk

My vote would go to Lithium batteries without a doubt . The last few months I have replaced quite few Lead batteries that didnt even come close to their " manufacturer claims" leaving me feeling like the idiot for recommending them 3 or 4 years ago. Plus the installs looks so much neater with a lithium battery. Much less wiring and space being taken up.

Keeping it in the spirit of the thread title breaker no 4 is not correct. That box can be seen as distribution board. The very first breaker (supply isolation) is referred to at the point of control and shall be a double pole breaker for single phase installations. It does not have to be a breaker you can install a double pole isolator there as well.

What exactly did he do ? But dont dispair we have resident expert here with issue regarding inverters and tripping earth leakages. Im sure The Terrible Triplett will be here soon to assist you. :-)

If all three the CB on the right are supplied trough the Earth leakage then it seems you have a problem. Breaker one and two neutrals goes to what seems to be a neutral point before the E/L. But I cannot imagine that’s the problem because it would trip all the time. Nevermind I see now Breaker 1 and 2 is not trough the E/L only breaker 3

Just to be a pain here but neutrals go to a common neutral bar not the earth bar ( I know what you meant but this might confuse other members) After the earth leakage neutrals and earths never touch, or obviously the earth leakage device will trip .

That`s a pretty wild statement to make. You might upset a few peoples feelings making statements like that in the public domain

Typically there won't be a local earth spike at the consumer for a TN-C-S and the PEN (C) is separated at the point of control which is at the municipal / utility meter in most cases