wolfandy

I have a single pole breaker like this. Installed after the main incoming breaker and before the inverter feed.

It's usually not just the frequency - same also with the grid voltage. Which is exactly why I have a smart breaker in my system to manually disconnect from the grid when I don't need it. So that my house gets 'clean' power and does not follow the Eskom mood swings...

+1 When running inverters in parallel, both inverters should be connected to the batteries via a common bus bar. I don't think it is possible to run a parallel system with each inverter having it's own battery. Also don't know if it is possible to run different batteries together in a system. I'd expect that you would run into all sorts of problems - as you are now experiencing. I would say that you have 2 options: Sell one battery and replace it with the same brand as they one that you are keeping Run each inverter separately (not in parallel), which would mean splitting your DB board across the 2 inverters I would recommend option 1

Am running 2x 5kW Sunsynks with 6x Pylontech - and am generally happy with my system. Yes, I do have a small issue with my system in that my slave has a higher battery draw when the system is connected to the grid. But I would call it more annoyance than issue. I have raised it with Sunsynk and they want me to send in both inverters to be able to replicate the issue - and to me that has not been worth it. The issue only presents when connected to the grid, and I am manually disconnected from the grid 95% of the time - so it is not bothering me really. Other than than, the system is rock solid and absolutely stable. I would recommend 2x 5kW over 1x 8kW/10kW to get the additional MPPTs for greater flexibility as well as redundancy in case there is a fault on one inverter. Batteries and both inverters connected to a common bus bar From what I understand, it is best to split PV strings across both inverters - e.g., rather have 1 string on each inverter instead of 2 strings on a single inverter and nothing on the other I would probably go with 1 battery and additional panels. I think you will otherwise struggle to get you batteries charged Your sparky will need to check. But if you install a 2nd inverter, then your initial inverter connection should be fine

Same on my side. I think this is because the BMS is only connected to the Master - and the Master does not seem to communicate the details to the Slave

Thanks I'll leave it to others with better knowledge of your inverter to advise

I am not an expert with those inverters. Am tagging @Coulomb to maybe chime in with his endless knowledge It seems that your inverter has 145V max VOC on the MPPT, so we would need to know how your panels are wired (e.g., 3 in series and that 3 times in parallel - 3S3P) A quick search here in the forum produced this thread, which might be of interest for you Where are you located?

Thanks @Ninoevans I am not sure if the data is an hourly snapshot (Watts generated and used) or cumulative Watt-hours (Wh) for each hour. But as an estimate it suffices. Based on your data, it appears that you have generated a PV surplus of approx. 5kWh during that day. Not knowing your batteries SOC makes it difficult to tell how far the batteries were discharged/charged, but based on your approx. 7kWh deficit from your chart (and not knowing how much grid was used for that), it would make sense that your PV is not able to fully charge your batteries. If you are discharging your 2x US3000 down to 20% (recommended for the older A/B models), then your surplus PV would not even be sufficient to charge them back to full. With the added US5000 that charging gap becomes even bigger... The other thing that I noticed from your charts is that your peak PV production is around 1.6kW - which from your total 3kW of panels appears low (depending where in the world you are based and which season it is for you). Which inverter are you running and how are your panels wired (e.g., all 9 on a single string in series)?

Hi @Ninoevans we'll need some more details to be able to help you. Could you please post some charts of your system from a typical day - e.g. load and PV production, battery power and SOC. Then we can better see what is going on with your system.

No way this is true. PV production is usually shaped like a bell curve. So the statement that 'the panels will produce 7kW all the time during the day' will never be true. Then also factors like direction of the panels have an impact on production. I am also based in CPT and here is the production data from my strings from this morning. Yellow is 6x 580W (=3.5kW) panels facing the morning sun and blue 8x 490W (=3.9kW) panels facing the day sun (main direction). You can see the ramp-up on both string. The yellow one makes a steep jump around 07h30 as the sun comes over the mountain. And you can see the drops due to cloud cover on both strings. By almost 11h30 neither string produces the nameplate capacity. So getting a constant production 'all the time' is just plain wrong.

Thanks @Zeus-JKR On the battery current, when you zoom in on the time period that your system is running on Grid (e.g., 02h00 - 04h00), is the battery draw still the same for both inverters? Strange - so we both get a higher Essential Load on our Slave, but seemingly caused by different things... Have you raised this with Sunsynk Support? Are you also based in SA?

That's the way it should be. Same cable lengths to each inverter from busbar? I am getting the same voltage reading on both inverters. Max. 0.1V difference I also get something weird running on grid. My Total Load is relatively even split: However, when looking at my Essential Load, the Slave is carrying a higher load than the Master: And for some reason, the Master is reporting a Non-Essential Load while the Slave is reporting a negative value for Non-Essential Load. This is particularly strange as I have no load connected to Non-Essential. It appears that the Master is pushing current across to the Slave: When disconnected from the Grid, Non-Essential Load is 0. Are you seeing something similar in your system? The other thing I have noticed is that the Slave is drawing significantly more from the batteries when running on Grid: Does this also occur in your system?

In my system, both report the same battery voltage. How are your batteries connected to the inverters? If I understand correctly, your system also runs ok when only on batteries but has unexpected behavior when connected to grid - is that correct?

@termdj: You posted your question twice. See my response in your other thread

If I am not mistaken 120V or 125V This is barely enough to get the MPPT started - if at all. So I am not surprised if you are not getting any production out of these strings As they are facing different directions, this will not help you much. Either put all panels facing the same direction or add more panels to each string to make sure that you have sufficient voltage on each string to get the MPPT started

I have also had issues with the slave in my parallel setup. I can't remember how the charging behavior was, but when the system was running on grid, the slave had a consistently higher draw from batteries than the master (0.8A vs 0.2A). And in general, when connected to grid, the slave seemed to run slightly different than the master. All cables same length, so not an installation issue. I was in contact with Sunsynk, who looked into the data and agreed that there was something odd. But they wanted me to send in both inverters for testing in their lab, leaving me completely without a system at home. And that I have not done yet. I am now running disconnected from the grid for most of the time and am ignoring the issues for now... @Zeus-JKR: Please post some more info/photos as well as data/graphs of your system, so that we can see more details on how your system behaves

Correct

I would put one connection cable from the fuses to the top battery (e.g. positive) and the other one to the bottom battery. The connectors between batteries. See picture in first post here

I think @Tinbum meant LiFePo. I certainly did. I switched from Lead Acid to Pylontech a number of years ago - and it was the much better investment. My Lead Acids did not see much usage, yet were also basically dead after 2 years. And if I remember correctly, discharging them below 50% even faster depletes their lifetime. LiFePo is the much better suited technology for solar systems as the batteries are designed for regular cycling (e.g. Pylontech US3000C has a design life of >6000 cycles, which means more than 15 years if you do 1 cycle per day). Even though the initial investment for LiFePo is significantly higher than for Lead Acids, see how long your last set lasted you and do the math how many replacement sets you would need to get to the same life as a LiFePo battery. And you get a much higher Depth of Discharge (DoD) on LiFePo, which means to provide the same amount of storage you would need a whole lot more Lead Acids. Absolutely no problem with LiFePo - they are perfectly safe. Google a bit if you want more details. I am not an expert, but I think those temps are on the boundaries of the working temps for most LiFePo batteries. They don't like freezing and you need to dramatically reduce the charging current when around those boundaries. So isolating the room to keep temperatures a bit higher would be a good idea. I did the same - but to keep the heat out and keep my batteries below 30°C as much as possible...

Do you really have temperatures below 0°C in the room where your equipment is located? Not sure where you are located, but I would expect that even if outside temps drop below 0°C, the temps inside would remain above that. Or do you really have ice formed inside the room where your equipment is? Otherwise I fully agree with @Tinbum. Lead acid or GEL are absolutely the wrong investment for a solar system.

I am not running a Victron system - so please don't take my word for it. But yes, the US3000C has a different CAN port (RJ45) than the older US3000A (RJ11)

I have been running 4x US3000A and 1x US3000C for more than 2 years. Absolutely no problem. You just have to make sure that you make your newest Pylon the Master

Hey @Toxxyc have you considered taking 2x 5kW inverters instead of 1x 8kW? Am not sure how much the price difference is currently. I went that route to have redundancy as well as more flexibility in terms of MPPTs (4 vs 2 strings), allowing me to have panels in 3 different orientations. Only thing to notice is that the 5kW inverter can only handle 13A per string while the 8kW can handle more (I think 17A)

I have a similar unit but from a different vendor (Tomzn), bought from Aliexpress. I use it to manually disconnect my inverters from the grid - and it has also been working absolutely reliable.

I have been running the predecessor POWR2 on my pool pump as well as the POW 316 Origin (without the screen) on my heat pump and 2nd geyser (2kW element) for more than 2 years without any problems. Yes, they are a bit bulky in size - but they have been absolutely reliable for me.