Patrick OReilly

I found this good topic elsewhere on the forum: Advice on wiring Sunsynk 5kW (powerforum.co.za) From there I've tried to edit my own diagram - specifically for the Surge Protection Devices. I'll post my new diagram shortly.

Thanks @Scorp007. My diagram uses an orange shade as the yellow does not show up well on a white background. Anyway, I'm not too hung up on using blue/yellow cables for the installation - it was more of a passing thought. I certainly don't want to have regulatory issues after the fact!!! 🙄

@Nicholas Strachan and @wolfandy and @Scorp007: Thanks for the feedback and info on the aircon loads. Regarding your experience with your aircons: Thank you! As with so many things, once someone talks you through it, it makes sense. So, my "concern" would be with the peak loads that occur when the aircon tries to move the room from one temp to another - but if the room is at the desired temp, then maintaining that becomes a much lower load requirement. So, I might just want to do the big temperature moves using grid power, and then do the maintaining off the inverter. I'm considering a central aircon system, rather than separate units in select rooms. I'm installing new windows with thicker low-e laminate glass (not double glazed), and I will put a decent layer of insulation in the ceiling. So, I guess I can expect that if I let the house get warm, then it will take a lot of power to cool it down, (or vice-versa in winter) but if I maintain it at the desired temperature, it will (hopefully) smooth the load to a low enough value to be able to manage on the inverter. And this will no doubt give me more reason to increase battery capacity in due course. FYI: Given my ambitions, you might wonder why I've not chosen to go with the 8KW Sunsynk. It is actually a strategic decision for two reasons: (1) I want to start with a system that will encourage me learn and to fine-tune my needs and behaviors. It may turn out that it is sufficient to my needs. And I'm a bit OCD, so efficiency is just intriguing to me. (2) But - should I prove that I can/need to use more - and that I can make it cost effective in the long term, I can add another 5 KW inverter in parallel, and then I have plenty capacity as well as redundancy. It looks to me like this is the route Andy has gone... 😉

I've also noticed some other diagrams have Surge Protection Devices (SPD) included. And there seems to be some debate about exactly where they should be, and whether they should have CBs in front of them too. Any advice on this for me?

@wolfandy - thanks for all the input! I have been feeling the urge I keep telling myself to optimize what I have before adding to it. But it's not easy! Interesting. I don't have aircons on this site - but I am considering a central aircon installation on another project I'm working for my own future home. What I'm battling to find is meaningful data/guidance on how much power these things actually need - and when. But I suspect I'll be learning by trial and error soon enough. I'm assuming all those heavy load items (geysers and aircons) are on your non-essential load DB? With that careful management of load, it looks like you can run on a 5KW inverter - is that correct? or do you have a larger unit?

Thanks @Scorp007. I was wondering about this - I've seen different diagrams where the Inverter is fed either before or after the MCB, and so I was unsure. But your point makes sense. Now, there is another breaker on the property where the power enters the building, but before it comes to the DB. I did not show this on my diagram (of course I should have... 🙄 It should be shown between grid and the CT) This essentially means the CB for the inverter sits between two other CBs. Would it then be advantageous to leave it where it is? It would allow for a scenario where something trips the Main DB MSCB without tripping the feed to the Inverter. Ah!!!! That is very sensible the moment you say it out loud. So, the change-over switch should be just 2-poles (Live & Neutral). This leads to a question: Should the earth bars in the Main DB and the Essential Load DB be directly linked to each other? I've seen diagrams drawn both ways, so I don't know which is correct! PS: I'm busy editing v2 of the diagram to reflect your advice... Thank you!

@wolfandy - thanks! I have noted the same - hours of throttled PV in the afternoon because there's no place for the power to go. I have couple of plans for future attention: The geyser at this site has a 4kw element. Simply switching that to a 2kw element will shave those peaks notably, and probably allow the combination of Solar plus battery to handle the peak, thus avoiding the need for grid input at the peaks. Installing a timer (dumb or smart) on the geyser to limit it to operating between about 10am and 2pm will almost certainly result in plenty hot water and a full battery at 4pm. And all of this will result in harvesting more of the sun - as you've noted. When this is the case, my next step would be to add a second battery so that we can make it through the night. This would also have the benefit of enabling the system to handle taller peaks on the odd occasion. Thank you for your input - it confirms that I'm thinking along the right track...

Indeed! Thank you Power Forum!

🙂 👌 Necessity is the mother of invention. Looks neat and simple. Well done!

My first Area of interest is regarding the wiring of the DBs and Inverter. I've googled and searched this forum, and read various manuals (SunSynk Inverter manuals), and battled to find a complete wiring diagram for the AC from Grid to Inverter to home load. There are many references and diagrams. Most seem to be only parts of the picture, focusing on specific details. And since I am not an electrician, I'm not always certain that I'm reading them correctly. So, from what I've read, I've drawn up my own diagram. I'd really appreciate your feedback on whether this is correct, accurate, safe and will achieve a CoC. Remember - I'm no electrician, so forgive my lack of use of all the "standard" circuit diagram symbols that may apply. Context: I plan to use a SunSynk 5KW Inverter, so this diagram is intended for that use-case. For example, the correct use of the CT and the Earth-Neutral bond relay are both important in this scenario. Here's the diagram: !!!Do not use this diagram - there are important improvements later in this thread!!! Key Comments and Questions: I have an empty wall in my garage, roughly 2.5m wide, alongside the existing DB, that I can use for the installation. I plan to install the Main DB and Essential load DB as physically separate DB boxes, with the Inverter between them. I've used the Yellow/Blue colours for Live/Neutral after the inverter, just to make it very clear what is before and what is after the Inverter. I'm not sure if I can get the cables to do it that way in the actual installation in the house. Question: It seems to me that the Earthing for the Essential Load should be independent of the Earthing for the Main DB, except when bypassing the inverter. But I'm not certain if the way I've drawn this is correct? (Since there is an RCD on the Essential Load DB, perhaps the change-over switch need only be two-pole?) Question: Following on the Earthing question above - when the grid is dead (not an uncommon occurrence here in ZA), we must rely on the Essential Load DB's Neutral, and thus also the Earth-Neutral Bond. Have I got this right in the diagram? Question: You'll note that I'm uncertain about the amperages of various breakers, so your suggestions on these is welcome. Question: I'd like to be able to remotely switch some of the Load that is on the Main DB, to take advantage of excess production at the appropriate times. Any advice on what WiFi switches are respected for quality and reliability for CBs for things like the Geyser, Oven and Aircon. (Sonoff? Other?) Looking forward to your comments and advice... 🙂

Hi all. Disclaimer: I won't be doing this myself - I don't trust myself just yet - but I want to be intimately involved, and I'm planning up front to see how it goes. So, I'll give detailed plans to the installer I select, and hopefully they will be GOOD plans. So, I think "Member Installations Showcase" is the best Forum for this project, and I'd appreciate your input and comments/advice as I go. This project is the plant 3 I've been anticipating in my signature. The spec will emerge as I go.

Hi all. @mzezman @I84RiS @jumper @Kalahari Meerkat @Scorp007 @GreenFields @wolfandy@YellowTapemeasure Apologies for coming back so late about this. Long story short - it's fixed !!!! Thanks to you guys who emphasized that my two strings were marginal on voltage, and for suggesting linking them into one long string instead. Now the system is singing. I've recorded some of the highest days of production in the lifetime of my system, and I've seen the panels peaking at 80%-90% of rated output on several occasions. Fantastic. So - what did I learn? if the open circuit voltage of the panels is only slightly above the rated "startup" voltage for the MPPT, system performance will be erratic. For best performance, you need long enough strings to get the voltage deep into the operating range of the MPPT. I had two strings producing a measured 132V, on MPPTs that have a minimum rating of 125V. Too close !!! I now have one string producing 250-260V throughout the day, and the other MPPT is unused, but ready for a fresh string when budget allows. Just for one example, here's a typical day now - the solar production runs strongly through battery charging phases as well as when load peaks occur, and it only throttles back once there is no place left for power to be used. (This also nicely shows the BMS managing the rate of charge once SoC reaches 90%, then 100%.) On this day, the peak production reported at 11:40 was 3.03KW, on panels rated at 3.27KW - that's 93% ! Thank you all- I'm now a much happier camper!

Good point - I'm learning as I go here - I'll find out more specifically what the panel specs are - for my own interest too. I'm guessing each panel is rated about 45V, since that is what is reported quite consistently, but I'll check. I'm now seeing just short of 270V from the string of 6 panels. This should put me nicely in the MPPT's sweet spot. Let's see how today goes - it promises to be a clear day...

Thank you. Strangely, my installer has come around to this idea now - I'm not sure what changed since the previous time we spoke... but it's good news anyway, and he's optimistic about it too. I'll be watching it today. We changed it about 12:45 yesterday (that's when the installer was able to assist), at which time the batteries were already about 80% SoC. It shot right up to full very quickly after that, but that was really not a good all-day test cycle.

A picture says a thousand words! Thanks @Scorp007 - that is very clear. My installer is suddenly on board with this idea (not sure what changed since I last mentioned it to him), but we'll do this change tomorrow. I'll definitely let you all know what transpires.

@Scorp007: Good idea for an easy test. If it works well then it is worth the effort of shortening the wires by linking the strings on the roof instead. I lost track in your words 🙂, but this is what I understand: MPPT 1 Negative connected to String 1 Negative. String 1 Positive series connected to String 2 Negative. String 2 Positive connected to MPPT 1 Positive. MPPT2 unused. Thanks to everyone for your input. I'll keep you posted on results...

It ranged from 27 to 33 deg C today...

I should note one other thing: For a long time (2 months) the battery dip switches were not correctly set, which means the Inverter and BMS were not communicating correctly. After correcting the dip switches (I forget the date, but it was early in this month) I've seen battery temps in the stats for the first time, and have observed how the BMS manages the rate of charge (slows it down) as the battery approaches full charge. I have noted this evening that the problematic behavior of this topic seems to have started roughly about the time that we corrected the dip switches, so that the Dyness BMS now knows it is talking to a Sunsynk (Deye). I'm not sure if this is at all related, but I thought I should mention it for full context.

Thanks @GreenFields, @Kalahari Meerkat and @Scorp007. I have had someone advise me to try improving the strings before, even going 6x1 string rather than the 3x2 that I have. All 6 panels are on one roof, at the same orientation, which is NNE. I'm space constrained there, so more panels are not an option right now. I did ask my installer about this, and he was quite adamant that this is not really an issue on a grid-tied system where the "start-up" voltage does not really apply (according to him, because the inverter is running already from grid, so does not need the panels/MPPT to "start up"). I, naturally, don't really know if what he's saying is correct or not. But as I now have 4 different people who have advised the same it's sounding like this is a must-try. FYI, below is a graph of the voltages recorded today. I note that the voltage remains much the same in the morning (when the power generation is good) and in the afternoon (when it tanks...). @Kalahari Meerkat: The Sunsynk 5KW inverter I have has a large heatsink behind it. To aid cooling I've positioned a fan on the floor blowing at it till I determine whether heat is the root cause or not. So far this has cooled the inverter, but has had no impact on the problem.

On another note: I met another installer over the weekend and bounced this off him. He was thinking the BMS might be sending "mixed signals". Even though it reports SoC below 100%, it might still be throttling back on the input current. This sounds perverse to me - does anyone else have any thoughts on this? Anyway, his two suggestions were: Try reboot everything and see if that helps. Tell the Inverter the battery is Pb (make sure all voltages are correctly configured) and let the system run like that for a while. If it then charges properly, this may indicate it is a BMS problem. I'm not entirely comfortable with (2). Even if the Inverter treats the battery as a PB and manages it by voltage, surely the BMS will still attempt to "protect" the battery? Thoughts?

Sorry guys - I was traveling for a few days... We have run for several days with the fan blowing. Temps are consistently 15-20 deg C lower (good!), but I still have the same behavior. I have 6 x 545W JA solar. 3 per string, which means they deliver about 130-132V per string once the sun gets going. SunSynk min string voltage is 125V. I'll include one here. Anyway, I was aware of what you're saying, and was only looking at scenarios where SoC was not at 100% and load was higher than PV, hence draining the battery while the sun was shining... This was another sunny day. In this example you can see it started well, got the battery charged by 9:00am. but from 10:30 onward load was consistently higher than PV, draining the battery with load less than 1KW most of the time, and PV staying below 500W, where it had reached over 1.5KW in the morning. It's like PV says "I'm only doing this once a day, then I'm chilling...".

Hi @mzezman. Thanks for responding. I have been making adjustments as we constantly try to balance efficiency vs this crazy Load shedding situation. But I don't believe any setting I've tweaked should cause this change. I do not believe I've had a firmware update, unless it would do that automatically without my involvement. Current versions are: M 3.3.7.4 / S 1.5.1.5 / C E.4.2.4. I know I verified that the version was up-to-date when the system was installed (30 October 2022), but I see there is a newer version available now. Last night my installer stopped by and checked physical wiring etc, which he said looked to be all good. He was concerned that the inverter felt very warm. We've put a fan to blow over it all day today and see if that helps. FYI - here is my temperature graph from yesterday - are these peaks a problem (DC:78, AC:57) ? Could this explain the degradation of panel generation capacity? You can see where we added the fan - just after 6pm last evening.

And today I see a similar pattern, though it did manage to get the battery to 100%. But since the rate of generation slowed about 9:00 am, it just won't come back up again, and now the battery is being depleted while the sun is blazing. I have 3.27 KW solar capacity installed. yet I'm only getting 1.2 KW in the first couple of hours of the day, and less than 400W most of the time. Please HELP...!!! For comparison, look at the behaviour on 1 November, 2 days after the original installation. That day we had intermittent clouds, but look at how strong the generation was throughout the day... Often generating at over 2KW.

If I may add a question: For SunSynk inverters, I see mention of installing a relay to activate earth-neutral bond when the grid goes down. There is a port for this purpose. But when I asked my installer about this, he was adamant that it is not necessary because the bond is managed internally within the inverter. So my Question: Does anyone here know for a certainty whether I'm safe running SunSynk with no Neutral-Earth relay installed?

Hi all. This is something very weird that happens quite often on my system. For the image below I've selected just the battery SoC and the PV input from the Panels for this morning. You can see that about 6am PV starts to push in power, and battery begins to charge nicely. Then about 8am, the rate of PV generation reverses - slowing down till it's barely making 10% of Solar capacity by 10am. But the battery has never reached 100%, in fact only just got to 80% before starting to discharge to carry load. The sun has been going strong all day, and I have no shading at all. Any ideas on what on earth is going on here?