cpbotha

The ES units are advertised as supporting 30% PV oversizing, so the total Wp of your panels can be up to 30% more than the rated PV input maximum. If you google around, you'll see that oversizing is often recommended, this is indeed to fatten out the power generation curve during the day. Just be careful, the MPPTs on that GoodWe have a 550V maximum (each). For your second string, rather get panels with a higher power output (Wp) so that you can keep the total voltage below 550V (i.e. not adding MORE panels), with a bit of safety margin.

Eish folks, let's all enjoy the weekend first! All of this is certainly quite frustrating, but we do seem to find ourselves on the cutting edge of the regulatory side of these developments. CoCT is moving, just extremely slowly, and they're unfortunately not doing the best job of communicating. Let's see what happens the coming weeks, especially with the new German regulations expert they have contracted for the coming two years. I'll try and get more info the coming week on the where and the when and the how.

I am currently shopping around for 16 of the Gen4 Canadian Solar 355W panels, to be delivered in Somerset West. Best price I have found so far is R2180.88 (VAT inclusive) from Solar Advice, see https://solaradvice.co.za/product/canadian-solar-355w-poly-perc-kumax-gen4-35mm-frame/ - I am still waiting for them to get back to me re delivery costs. Does anyone have any other supplier tips?

@plonkster I have found the document from which your block diagram was taken. It's the TÜV Rheinland certificate of conformity to NRS-097-2-1 2017 for the GoodWe EM series, and it's quite insightful to read through. You can find a PDF at https://solaradvice.co.za/wp-content/uploads/2017/10/EM-SA-test-report.pdf (I could not attach the 3.5MB PDF due to the 3MB attachment limit here.) In the document, you can find how the certification authority directly handles each of the NRS requirements where it concerns the inverter being investigated, for example: NRS clause 4.2.2.2.1 "The embedded generator shall be equipped with a disconnection device, which separates the embedded generator from the grid due to abnormal conditions" ... with the response "PV inverter provided two relays in series used in each line and neutral as disconnection devices" and verdict "P" for pass. That easy. You'll probably find section 4.2.2.4 on anti-islanding interesting. (With regard to my own plans: I have decided that it's going to take too long for CoCT to catch up with us, and am going to bite the bullet with the GoodWe EM 3.6. It's on the 2017 list, and it satisfies the max power output requirement. In other more interesting news: The director of SARETEC has told me that CoCT is flying in an expert from Germany who will work for them for the coming two years, also to help with the applied regulatory aspects of PV Solar SSEG. I also suggested to him that CoCT should have a workshop with a number of the most knowledgable and trained folks from this forum, to help disseminate CoCT regulatory information. Watch this space...)

Hi there @Fuenkli - I would like very much to keep up to date with your CoCT sign-off endeavours. As you know, I would also like to get in the same GoodWe boat as you, but I'm currently flip-flopping between the 3.6kW EM (purely because of all the confusion around CoCT regulations) and the much more preferable 5kW EM or the 4.6kW ES. At this moment I'm almost ready to give up and just get the 3.6kW to play it safe.

Just to add to that, below is a section from page 8 of the GoodWE EM series user manual ( http://www.goodwe.com/Public/Uploads/sersups/EM USER MANUAL.pdf ) where they recommend installing an SP3T switch to be able to manually switch backup loads back to the grid if required.

@Rautenk and others who are into this ( @plonkster , I have just run into a detail in a GoodWe installation manual (and then in the GoodWe docs) that sheds some more light on the "the storage can be used to reduce the effective size of the generator" question. If you look at page 3 of http://alpspower.com.au/wp-content/uploads/2017/12/Goodwe-5048ES-with-BYD-B-Box1.pdf take note of the following text: "Do NOT connect the grid to inverter's back up part under any scenario. The inverter could be damaged if there is power flows into the inverter from back up part. To improve the system reliability, Goodwe recommends installer to install a changeover switch between back up load and grid tied load. Then for rare case, if the inverter is faulty, customer could manual switch all essential house loads back to the grid side." In other words, all of the essential loads are in fact disconnected from the grid when the inverter is down. When the inverter trips (as defined in the NRS document) the essential loads CAN'T be transferred to the grid, only loads on the non-essential circuit. So, if the inverter generates its maximum 5kVA and for argument's sake is not using any grid at that moment, and then trips / shuts down, only 5kVA minus 4.6kVA (its backup power) which comes to 0.4kVA of load can then be transferred to the grid. In other words, this specific setup will easily satisfy the 25% rule. A demonstration of this would be to have e.g. a 1kVA aircon on the essential loads circuit, and then manually shut-off the inverter, at which point the aircon will simply die, and zero change in power flow will show on the grid side. Does this make sense?

what does this all mean? I tried unsuccessfully to figure it out. Can you please explain in simple terms if it is possible to legally connect a hybrid inverter like the Goodwe 4.6 kW to a single phase 60A grid supply. @Rautenkin a post further down you say to just get the main breaker upgraded. However, the second answer above that you got from CoCT was to do with your very specific question re the connected storage, and how it affects the effective generation capacity. Are you any more clear on that specific topic now? CoCT simply referred you back to the definitions, unless I'm missing something?

Could you please provide me with more information on this, what do you mean charge / discharge capacity limits into connected local storage. Are you referring to Battery Charge Controller limits? The specs on this specific hybrid inverter, the GoodWe EM 5kW, claim that in battery backup mode it can sustain 2.3kW to the house from the attached batteries (the so-called local storage), and it can supply 10 second peaks of 3.5kW from these batteries. I mentioned this, because in other cases, the inverters are able to deliver their full rated output from battery power only. Anyways, I am super curious to hear what your CoCT contact says about how exactly storage (batteries) reduce the effective output of the inverter! (I have read the "NOTE 3" exception you posted over and over, and it is slowly making more sense. I am now wondering how to prove, for generation that exceeds the 25% limit but has storage "included", that when the generation trips, the load *delta* suddenly transferred to the grid can never be > 25%. The fact that they specifically mention this configuration, means that there are cases where it can be shown. Super curious!)

Wow, thank you very much @Rautenk for this, and your other posts! I read through the rest of the thread, and tried to understand as much as possible. (E&E by training, but got lost in software like so many of our colleagues, and so I'm definitely out of my depth here. How exactly should I interpret "the storage can be used to reduce the effective size of the generator"? If my hybrid inverter is the NRS 2017 approved 5kVA EM-series, with a change / discharge capacity of 2.3kW (3.5kW peak for 10 seconds) into connected local storage, does this mean the effective size of my generator is 5 - 2.3 for the intents of the regulations?

If what exactly is out of the range? Maximum rated total inverter output, or output to the grid? Also, do you have experience with the "asking special permission" bit? If you can share anything with regard to your CoCT sign-off experiences, I would be most grateful to hear!

NRS 097-2-3 states the following in section 4.1a: "An individual limit of 25 % of NMD will typically support a penetration level (percentage of customers that install a generator) of 30 % to 50 %, which is considered a reasonable and acceptable compromise between restricting individual generator sizes versus restricting penetration levels." I am not sure in which interpretation of this statement is the correct one. Further down under 4.2.1 we have: "The maximum individual generation limit in a shared LV feeder (see figure 1) is approximately 25 % of the customer’s NMD, up to a maximum of 20 kVA (generators greater than 20 kVA should be connected through a dedicated LV feeder)." ... which sounds like they are concerned with how much a customer generates back into the public grid.

Interestingly, the SSEG requirements document states on page 18: "Generation Capacity refers to the total output capacity of the generator. For PV systems in particular, this refers to the maximum output of the inverter as limited either by hardware, or by software settings." So they do explicitly support software limiting of the maximum output. With the GoodWe ES, if you want to limit grid export, you install the so-called EzMeter and CT clamp (included) on the house supply. Now you can export limit to anything, also 0. I would still very much like to hear if anyone has experience with getting the city to sign off (or not!) larger than 3.5kVA inverters which have this sort of export limitation.

Based on my initial reading of Cape Town's "Requirements for small-scale embedded generation" [1] (see page 18 for the limits) I interpreted the maximum inverter output limit (3.5kVA for a 60A breaker) as holding even when ZERO feed-in / export was configured in a grid tied system. However, when I read through NRS 097-2-3 [2] (see around 4.2.2 for example), I'm starting to doubt my earlier assumption. Could it be that the "generation limit" does refer to what is fed back into the grid, and NOT to total inverter output? Does anyone have actual experience with successfully signing off an inverter with a rated output larger than 3.5kVA on a property with a 60A breaker, where the feed-in to the grid has been limited using an approved mechanism? [1] http://resource.capetown.gov.za/documentcentre/Documents/Procedures%2c guidelines and regulations/Requiremenst for Samll-Scale Embedded Generation.pdf [2] http://pqrs.co.za/wp-content/uploads/2015/03/NRS-097-2-3-final-2014.pdf

Indeed, the specs of the ES and the EM even state that you can only have one string per MPPT. On the other hand, you get two MPPTs, each of which can go up to 550V.

I am posting this information here, because I could not find anything online before. I just received confirmation from [email protected] that the GoodWE 3648-EM 3.6kW inverter, rated for 4600W max PV input, does support PV oversizing by ~27.8%. (In the brochure for the ES units, GoodWE explicitly advertises 30% PV oversizing. However, this is not mentioned in any of the EM-series documentation, which is why I sent them this request for information.) This is the email reply I received from [email protected], within one business day:

Hi there @The Terrible Triplett! As a Linux nerd (there is even some of my code in the kernel) and an engineer, I have to actively *resist* the attraction of Victron's hardware and software. However, if I have to be 100% honest, the GoodWe solution currently looks like it suits my situation significantly better than the Victron kit. (If Victron had a 500V+ MPPT available, things might have been different.)

Thank you very much for pointing out those footnotes @plonkster - the GoodWe ES 3.6 seems to be a much more attractive proposition than the equivalent EM due to greater battery charge / discharge (3.6 vs 2.3kW). Also, the ES specifications explicitly specify its support of 30% PV oversizing, which the EM specs do not. In the meantime I have been doing more reading and budgeting: In my planned configuration, the 2 x 550V MPPTs built-in to the GoodWe make things really easy. As you have often mentioned before, the equivalent Victron Multiplus-II + VenusGX + 150/100 MPPT is, although a lot more flexible, about 15% more expensive parts-wise, and hooking up the solar arrays becomes a little more involved due to the 150V per-string limit. (could go for the 250V MPPT, but that obviously has a further impact on the total price)

I heard that inverters with NRS 097-2-1: 2010 certifications but no NRS 097-2-1: 2017 certifications would still get City of Cape Town approval during 2019. Can anyone confirm this, or does anyone have any more information? Here is CoCT's list of approved inverters: http://resource.capetown.gov.za/documentcentre/Documents/Forms, notices, tariffs and lists/Approved Photovoltaic (PV) Inverter List.pdf You'll see that some of them are "Yes" in the NRS 097-2-1: 2010 column, but "No" in the NRS 097-2-1: 2017 column.

Total newb here, but did you remember to plug a VE.Can terminator into the second VE.Can port of the Venus GX? (I remember reading the docs https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom yesterday, and specifically that the battery would turn itself off without the VE.Can terminator.)

Just in case anyone else was also searching for this, here is the NRS 097-2-1: 2017 certificate of the Victron MultiPlus II: https://www.victronenergy.com/upload/documents/Certificate-NRS-097-2-1-17-18-320-00-MultiPlus-II-and-MultiGrid-II.pdf Thank you very much @plonkster for that webinar, it really increased my understanding of how the Victron works, and just in general what my options are with battery-backed solar PV:

Dear @The Terrible Triplett and @plonkster thank you very much for this!! ( @plonkster cool to run into fellow CFMer here! Let me know when you're in the neighbourhood of Paardevlei for good coffee (my office is there, different type of engineers, LOTS OF COFFEE going down)) Wow, to my inexperienced ears this sounds like what I need to be able to get more panels on my roof. It will be easier to charge battery during the day AND feed AC into my home for longer. I can compensate for the slight hit in inverter output kW by staggering my geyser ON periods. @plonkster Do I understand correctly that I can attach more than one MPPT to the MultiPlus II and further that you work for Victron (or have knowledge at least as deep as their own engineers?) :)

Dear all, Together with an installer here in Somerset West we are looking at options for a grid-interactive PV install, compliant with current City of Cape Town regulations, with battery backup but no feed-in. (Cape Town wants you to pay R11k for the new smart meter, which they own, as well as a R14.90 / day levy. This, together with the advantages of battery backup in the context of load shedding, leads me to remove feed-in from the list.) The main problem is that even when NO feed-in is required, the inverter maximum output is limited to a maximum of 3.5kW (see page 18 in http://resource.capetown.gov.za/documentcentre/Documents/Procedures%2c guidelines and regulations/Requiremenst for Samll-Scale Embedded Generation.pdf -- my house has a 60A breaker), and this usually has implications also for the maximum PV input. The config which we are currently looking at consists of: 16 x 275Wp panels for 4.4kWp. GoodWe is limited to max 4.6kW. The GoodWe 3.6kW EM series hybrid inverter see https://thepowerstore.co.za/products/goodwe-em-3-6kw-hybrid-inverter-2-3kw-backup (this is on the CoCT list, with 2017 NRS certification) 2 x PylonTech US3000B lithium ion batteries, see http://www.pylontech.com.cn/pro_detail.aspx?id=121&cid=23 PV roof and DB are well situated relative to each other. However, wiring up separate panels for geysers and maybe upgrading to PTC elements, although a good plan on paper, is going to be tricky due to location. With 6 inhabitants, we use anything between 25 and 35 with peaks of up to 50kWh per day. Major consumers are the geysers (already all on GeyserWise timers), a big 3kW aircon and of course our old friend the 1kW swimming pool pump, which I do limit quite severely. (the recent 50kWh day was super hot, main aircon + running pool pump did most of the damage) The config above could work, but I have a great north-facing inclined roof which definitely has space for more panels. However, the only other inverter (as far as we know) which satisfies CoCT inverter output limit (through a firmware configuration) is the SolarEdge SE5000H, see https://www.sustainable.co.za/solaredge-se5000h-5kva-hd-wave-grid-tie-inverter.html This does require power optimisers on each and every panel, but the main deal-breaker is that it only works with high voltage batteries such as the Tesla PowerWall 2 or the LG Chem RESU batteries, which will take this project into impossible budget territory for me. Do any of you experts have any suggestions w.r.t. inverters or inverter configurations (or other system changes) which will 1. satisfy cape town's 3.5kW inverter output requirement and 2. enable me to get a kWp or more extra generation capacity on the roof? Thank you very much for reading this far!