Elbow

So I looked again at the old board where my supply connects. I can see that the power arrives in a sort of coaxial cable. the centre (live) goes through a breaker to the old meter. The screen heads off into an old metal box ("R10 fine for opening") and out of that box comes two earth wires - one goes to an earth spike and the other used to go to a nearby water pipe. Now its loose - not sure if that is a fault or whether the rules changed? Anyway - from the same black box emerges a neutral that goes into the old meter. Out of the meter a live and neutral heads down a conduit and presumably to the main board inside. BUT - there is no earth wire going to the main board. Now my competent electrician friend did check my house when I moved in and the earths at the plugs do have a low resistance back to earth. So where does it connect? Does the main board actually depend on the neutral wire from the bonding point as earth too?

Hi, I was looking for a clear explanation of TN-C-S earthing. I found what was a very clear video on youtube: Earthing Arrangements TN-C-S in a Single Phase Installation and in Picture form to aid with Exams Short version: "Terra (earth) and Neutral carried on a single conductor on the distribution side, but separately in the customer wiring. There's an associated term "PME" - Protective multiple earth - which simply means that the distribution network earths the neutral at multiple points along the way. Which tries to ensure that the earth is not lost. In my house that appears to include actually at the point where the supply cable terminates. Be happy to hear further info about TN-C-S design.

I'm guessing those outside of Cape Town are getting bored of the SSEG registration process. Perhaps a forum for us would be a good idea. But in the meantime - can anyone give me a start on the tricky questions in the form - hoping that others who have filled it in might give me some pointers: "MAKE AND MODEL OF KEY GENERATING EQUIPMENT" So in my mind it is the panels that do the generation, but my impression is that they are looking for the inverter info. What do others say? Then, "ELECTRICAL PARAMETERS OF EMBEDDED GENERATION" Again, not clear if this is panel info or inverter info. Mostly these seem to do with a generator, as per the note above If not, any ideas what goes in here? "ELECTRICAL PARAMETERS OF GENERATOR AND UNIT TRANSFORMERS" Are we on the inverter now? "PROTECTION DETAILS" Here's where all the trouble lies - must say I'm not sure where to find out this stuff about my inverter. And lastly - "LIST OF REGULATORY APPROVALS, REQUIREMENTS AND NORMATIVE REFERENCES" -- what to do with this long list.... With my choice I'd say there are all N/A 😉

I don't think you are understanding. It's not about the feed back, it's about the stopping of the feedback. Let's say 100 10kw sseg systems in a neighbourhood. Pushing 1MW into the grid. Maybe there are 1000 homes behind that transformer and drawing average of 2kw each, so 2MW of load. Half the load is being carried by the solar systems. Oops - brown out. All those inverters follow all those fancy requirements. So klunk klink klunk, they all drop off the grid at the same time. But all those houses didn't get the memo and the stoves keep stoving, and the geysers keep geysering, and etc. So suddenly that transformer has to double its output. Since a Power grid is an ac system - a very very low frequency tuned circuit - it is not going to enjoy that sudden change. I guess the result could be bang for that transformer, a trip for the whole area, or...?

Yep - I remember your post. As you see I used 32A coming from the inverter, though I’ve put the plug circuits behind a 15A breaker to start with. This is because I don’t have PV yes, so it is being used as a UPS and without grid it will be limited to 3000va. When o do my PV panels I’ll experiment with a high breaker rating; though I’m hoping that CoCT will agree that I can grid-tie it and I’ll rather support the heavy loads on the grid-tied side. Your figures are impressive - 7kw total on a 3000va rated inverter!

Yes, I was able to tweak my Infinisola settings, thanks. I made up this board to get going: Top row: 32A 2P trip from grid, indicator for grid, 2P 32A trip from inverter, indicator for inverter, change-over switch, RCD Bottom row on the left are fed from before the RCD and are my red plugs for the computers and 3 lights Ccts. all 10A. On the right side at the bottom these are the plugs circuits. I put one 15A trip for them all, and then 3 10A for three plugs circuits. The idea is that hopefully an overload on the plugs will trip that 15A trip and leave the computers and lights on.

House was built in 1974 and I’m sure these are original.

It makes sense that modern grid-tied inverters are safe since they are designed for Europe / UK etc where 3-ish kWp grid-tied PV systems are common. Usually grid-tied, often with no batteries. People are highly incentivised to install them with rebates and generous rates for feeding back to the grid. The inverters are microprocessor controlled and intelligent. Came across this with a quick google: https://www.greentechmedia.com/articles/read/solar-broke-records-all-over-europe-this-summer . 533 gWh in a week (peak summer of course). And this comment in that article: So I think the scale here should be of little concern and could be welcomed. 107Gwp is 35.6 million 3 kWp systems. In South Africa we have 10-million ish formal houses best as I can find. So 1m PV systems is a very ambition figure. 3GW total. How about that - nearly makes up for the amount that Eskom has to shed the other week. In the draft you shared, though, there seem to be some backward looking assumptions about batteries with stuff about battery boxes, acid and corrosive gases and ventilation and all that which doesn't seem too relevant to modern Lithium-based packs (which may have safety issues of their own but they aren't acid spills, gassing and etc). So it looks like that area needs attention to modernise. Perhaps the drafter can be approached to ask if stakeholder input would be valued?

You've got some serious Google-fu.

On the side of my house I have this old meter - no longer used, and the wiring you see. My power comes through here since throwing that breaker turns off everything. The red sign says "Earthed to neutral" or "aan Neutraal geaard" i do have an earth rod down below which I assume is connected somewhere here too, The breaker is 80A. Not sure what’s in the box bottom right that is labelled 25A. The R10 fine is a scary thought! Can anyone tell me how this works and what goes where? Is this TNC-S?

Yes - I'm going to follow the process with the City and see what happens - hoping for a good experience. I don't think its a good idea to be trying to go around the SSEG team without giving them a fair go. @Rautenk will help me with the engineering signoff when the time comes - assuming he is not fedup with this all - so if he is willing to take technical questions to the council it will help all of us.

Yes - it's weird that later on an engineer must sign off, but at the initial stages its a paperwork exercise. It's kinda two-minded - if an engineer must sign off then let the engineer sign off and finished and klaar. My brother in law is a GP and for them the medical aids are like this - a clerk at the medical aid tells the doctor what s/he can or can't do based on bureaucratic rules and regs.

I think this is great. Thanks. I just did "Step 1: Log a service request" to start my process so lets hope this road isn't too bumpy.

I started my process now, submitting the "service request" that is step 1. I'm nervous to put my head over the parapet, but hopefully it will be a positive experience. As you say I've generally had a good experience with the council up to now. My risk I think is that is will be hard to get exact circuit diagrams of my inverter to prove it has the necessary dual interlock and things. But it's on the list so maybe this will actually turn into a form-filling exercise rather than a real technical evaluation.

Hi all, I think there was a "group buy" a couple of years back, but where do people get or make the required stickers for your PV system? If there are templates then I can print at work on to sticky sheets. Thanks!

Hi @Youda, Yes, I didn’t have any alarms before I was leaving the batteries on 52v float. But I can’t say if it’s related and didn’t have a chance to figure out if the bms has a log and how to get it. Your suggestion also floats at around that voltage but maybe using a higher bulk charge voltage as a "step" is a good idea that might help the balancer, that I will try. After reading various things about Lithium including some Pylontech info, I had previously setup my system to charge to 51.5v and then turn off the charger and let the batteries drift down to 80% SOC or so and then cycle them. Like a mini-cycle. That seemed to work quite well and I did it that way on the basis that Pylontech said that the best way to store batteries is with mid-charge rather than full or empty. I will try your approach. Once my PV is in it will become moot since then I’ll use them as intended rather than floating them all the time.

It was @SolarNoob who said this is jot balanced. I didn't see it as a problem. I'm just data gathering to see how the battery behaves in different conditions. I would be inclined to use a lower charge voltage on the basis that Victron did so, and because avoiding extremes od charge and discharge is good for cell life.

Hi, It’s a very interesting and valuable exercise to make sure you really know where your electricity is being used. You need to understand which equipment uses the most energy in a month - here’s where your PV can save you money, especially if the usage is in the day. And you need to know which equipment uses the most power and when. His current draw makes your inverter expensive. You will find that innocuous looking things that run all the time use a lot of your killowatt hours. ‘There is also a class of usage where you can control where its used - run the dishwasher in the day and not the evening. Things like a pool pump you can even turn off automatically if you need the power for something else. Meters are available that you can use to monitor, I installed something called Openenergymontor that gives me a ton of insight:

Hi, I discharged my batteries to about 95% and then charged using 53.2v as the bulk and float voltage per the recommendations for a Voltronic. it does seem to make much difference - again, when the cells get near full a voltage difference creeps in - currently at 0.7%. Here’s the big picture chart: Left scale is cell voltage - blue and orange - and right scale is actual charge amps - red - and "max charge" as signalled by the battery on the rs485 interface - green. You can see that I charged at the 53.2v and the cells did get higher, but overall the balance was about the same. Zoomed in: You can see that the cells did rebalance somewhat as the charge current dropped. But only so far. Here is the very detailed chart: I think I’m going to stop worrying about this, though.

Thank you sir - I feel encouraged. I'm going to stop muttering and send in my application and take it from there. I'll use my inverter's support for a Modbus card and an external energy meter to block reverse current flow.

So mine is on the list. Can I submit a design which grid ties it and just say "you approved this inverter", or do I need tons of additional paperwork. If so, why? Why can't the council just say "your design needs the following additional elements" in an understandable way.

http://www.capetalk.co.za/articles/339652/fix-the-red-tape-and-rooftop-solar-pvs-will-lighten-power-burden-energy-expert

54v is 3.6v per cell. The absolute maximum a Lifepo4 cell can "survive" is 4.2v, but it damages the cell. The Pylontech are following a sensible figure no doubt trying to maintain the life of their battery. 53.2v is 3.547v per cell - and to stop charging when the cell voltage is 3.5-3.6 is good practice - they’ve split that almost exactly down the middle; So I don’t think hacking this in the firmware is a good idea. This chemistry does have a very flat voltage curve so different from Lead acid where voltage maps quite linear to SOC. 52v is 3.4667v so a little less than 100% charged. To play fair with Pylon I will charge per their application note at 53.2v and see how it goes as a test. I tested 51v and that gives 90% SOC which actually might be a good figure for a long life, but I went to 52v following the advice of the master, @plonkster. My observation in other tests is that there is almost no energy stored in those final 10ths of a volt. I don’t think my alarm light has to do with this, though.

Here is one of my batteries recharging: Basically the cells discharge in very close balance. They charge in very close balance. It is only right at the end that the imbalance appears. This is with charging at 52v. 52/15=3.4667 which is pretty much where the cells ended up, only slightly imbalanced. I think I switched to constant voltage float a little too soon. I’ll redo this test using 53.2v and see how these curves look.

Yeah - it's frustrating. I think most here are responsible and willing to follow a reasonable process to ensure our installs are safe for ourselves, our neighbours and city staff. But the process has just ended up SO confusing and complicated. The documents are not clear in my opinion. I wrote up what I didn't understand and sent it to Karel and it seems what I don't understand are exactly the points that aren't clear to him. And I don't think they are clear to the administrators of this process either. So my inverter is "on the list". It also (supposedly) supports a Modbus card so I can use an energy meter at the main feed from the grid to ensure no nett outflow to the grid and avoid having to pay for the 2 way meter which doesn't really make sense for me. And it has anti-islanding. So am I done? Is that acceptable to grid-tie it? I'm really not sure. If I might need other devices then I'm really not sure how to find out what I might need. At the moment my inverter has no panels so its a UPS. So it just needs a CoC and otherwise no need to register it and more than I would register a APC under my desk. This might be where I should stop - I've got load shedding protection for my computer stuff and could keep the lights and some basic stuff going. If I add panels - which I want to do, in order to improve my return on investment, then what? Maybe I should just make it off-grid. But the regs hobble it. They say it may not be connected to the grid and _cannot_ be connected to the grid. I suppose that means I must disconnect the mains input completely: like remove the wires, the input breaker etc. That's what @The Bulldog wrote above and I think that is the way the wording goes. Which means I must limit the loads to what I am confident can be reliably supplied by the panels even when the weather is crap. That of course is a shame since on most days a lot of energy will go to waste. My inverter can easily be configured to never push back on the input side but it seems that isn't good enough? On the other hand if I apply for grid-tie on some basis it seems it will be many many months before I can actually commission it. And very unclear what design is acceptable. It feels like it could cost 10s of 1000s of rands to get it all done and that really kills the cost-benefit. So I'm willing but feel unable and actually absolutely unclear as to what I should do.