wolfandy

I think you can use Aux to supply power only when you battery is above a certain SOC. But am not sure if it will use grid or simply not provide power if below the SOC Correct Am not 100% sure, but think so

That understanding is incorrect. For as long as the grid is present and your SOC is higher than in your setting, the Sunsynk will draw on whatever energy source it has available (PV and/or batteries). When the SOC is at or below your setting, it will use grid to supply both essential and non-essential load. If you have PV available at that point, it will use whatever PV is available and supply the balance from grid. When the grid is down, it will only supply your non-essentials (either from PV and/or batteries) Correct. You need to play around a bit and find the settings that best work for you. Here an example of mine: At the moment I have 20h00-02h00 set to 45% because we are going to have loadshedding from 02h00-04h00 (usually set to 40%). The 02h00-10h20 is currently at 35% because we will have overcast weather tomorrow morning (usually 30%). I typically do now draw my batteries below 30%. I would rather make my geyser 'smart' (e.g. with Sonoff device) and put it on a timer to better control when it comes on. And then set it to only come on during times when I have sufficient PV available

I would also compare price against 2x Pylontech US3000C as alternative option (I have no clue about current pricing and availability)

I have previously used an external MPPT to charge the batteries using a busbar. The batteries, the MPPT, and the battery input of the inverter were all connected to it. Worked perfectly. Biggest challenge is getting the charging settings right across all devices connected - e.g. synchronizing multiple MPPT or between MPPT and grid charging. Other small downside is that the inverter obviously is always thinking that it was running on batteries while in reality the power feed comes from the MPPT. But that's only a 'display' problem and not a functional one.

Correct. Take a Pylontech US3000C as example. It has a capacity of 74Ah and should not be discharged/charged continuously with more than 37A (roughly 1,800W). So even if your inverter is capable of providing 5kW, your battery will limit your system to around 1.8kW while running on batteries. Which for your case of lights, TV, etc. should be enough. But it also means being diligent and not switching on a kettle while running on battery. Of course, if you add more batteries to your system (at a later stage), then your system capacity will increase (e.g. 3x Pylontech US3000C will allow you to fully utilize the 5kW inverter) No, the C rating is only relating to continuous power draw. E.g., for a Pylontech US3000C the depth of discharge is 90% (so down to 10% state of charge). Hence of a nominal capacity of 3,552Wh you can use 3,374Wh Correct. A Pylon US2000C with 50Ah capacity has a max. continuous discharge/charge of 25A (roughly 1,200W) Correct. A Pylon US2000C with 50Ah (2400Wh) nominal capacity and 90% depth of discharge has a usable capacity of 2,280Wh. That roughly means 1,100W load for a period of 2h

Check out the SolarAssistant website (https://solar-assistant.io/). There you can see all features in detail. For me, it is much more user-friendly than the Sunsynk app

I have a 'basic' setting that I use for normal days and light loadshedding. If we're in higher stages, then I dynamically adjust my settings based on the expected time of loadshedding. That's where for me SolarAssistant is absolutely worth the investment as I can change my settings whenever I want to and from wherever in the world

Yes. Between purchasing my 1st Pylon and my 5th was probably around 2 years. You can add batteries whenever you want (can afford)

To my understanding the derating is not outside a sweet spot - but if you exceed the MPPT voltage range. In this case the upper limit of the voltage range is 425V and the hard limit is 500V. @Coulomb at one point explained this in more detail for an Axpert, but I cannot remember exactly where...

Take a look at SolarAssistant

MPPT Voltage range is stated as 150-425V. So I would try to not exceed 425V. Usually the MPPT derates above that. I would probably start with 8 panels and see how my string voltage performs for a while. Alternatively there is a calculation tool from Victron somewhere online that you can do detailed calcs with based on your panels specs, expected temperatures, etc. Oversizing should only be done on Amps, not Voltage. If you exceed the MPPT voltage, it will ' go poof' So yes, try to get to the 425V as close as possible, but make sure that never ever you could exceed 500V (e.g. sunny days in cold weather)

Agree with @Kalahari Cruiser Rather put 1 string with 8 or 9 panels. Do the exact math to make sure you stay under the 450V limit of the MPPT

Correct

I'm not a sparky or installer, but I previously had a Keto between my batteries and inverter. Now I have something similar to a Keto. No extra breaker required. If I need to disconnect the batteries and inverter, I just pull the fuse

To me it seems that the batteries are balanced. All of them are at 41.8V. So I don't think this will solve the issue Do you regularly charge cycle them? To me it seems that them BMS of the one Pylon is off. Because at the same voltage it is reporting a way different SOC. My Pylons are usually also all at the same voltage and I get small differences in SOC, but less than 5% - nothing like your case. Maybe charging to 100% and letting the individual cells balance can help get the BMS 'back to normal'? Or something with that Pylon is faulty

Am not familiar with your inverter, but in most cases the house will run off PV as much as is available. And it depends on your settings. But usually, if your load is less than your PV production, it will completely use PV and use neither grid nor battery. If your load is higher than PV, then it will either use grid or battery to supply the difference (depending on settings). When we have loadshedding, the inverter can obviously only supplement from battery Why not? In my view, that's what the battery is there for. Supplement a short-time shortfall of PV from battery rather than grid and later recharge the battery again with PV once load drops below PV again If I read the specs correctly, the start-up voltage of the MPPT in your inverter is 120V. You want to make sure that you are well above this with your panels - otherwise you will hardly get any PV production. Not sure what the exact specs of your panels are, but 4 panels will probably put you somewhere around 160V. Your MPPT can take up to 385V, so it might be better to rather make it 5-6 panels if possible

I will need to follow up again with my installers. One of them put the permanent bond in after he has had problems with relays at other installations. To my understanding, he puts permanent bonds in all his installations now

I have to admit that I am still confused about this. The 2 installers I have spoken to both say that it is legal in SA.

I assume that you have a comms cable between your Sunsynk and your Pylons? Then the Sunsynk will get the charge amps directly from the Pylon BMS, which overrides these settings. You can check you BMS screen on the Sunsynk. If you see SOC, Charge Amps, etc. there, then you don't have to worry about the settings you are referring to. The BMS will actually dynamically adjust the charge amps based on the SOC. Unless he has a permanent bond

I managed to get some off-cut pieces from Isoboard, of which the thickness perfectly fit into the cavity between the door and the struts running across on the inside. I originally tried to glue the pieces to the inside of the door, but they did not stick properly. So I ended up putting additional metal bars across the door to hold the boards in place. And I painted the boards charcoal afterwards to better blend in. Very basic, but reduces temps by about 2 degrees

I have the same problem. I have put some insulation on the inside of the garage door, which has already made a noticeable difference I have also added a floor-standing fan (controlled by smart relay) pointed at my batteries to keep them cooler during the day

Brief update: The trips now also occur when disconnected from grid. A sparky has meggered the whole house. All circuits are clean. I have taken out all surge protector plugs I had in the house (red or green plugs). This seems to have reduced the number of trips - but they still occur. My sparky has taken a few sockets to which only computer equipment is connected off earth leakage (turned into dedicated plugs). Now the E/L trips when I switch on my home theater system - but not every time. Sometimes I switch on the system for 4 times without problems, sometimes it trips every time I switch it on. The system is fed via 2 separate circuits with the main power amp on circuit 1 and the rest on circuit 2. I am running out of ideas on what to do. Does it make sense to take more circuits off E/L (e.g. aircons)? Can I take the circuit to which my main amp is connected off E/L?

Am also still battling with earth trips. For me, replacing the E/L actually made things worse...

I found that my inverter temp is mostly driven by PV production. The higher my PV production, the hotter my units get. Load to me seems to be a smaller contributing factor. E.g. the temps are similar at 4kW PV production with little (1kW) or high (4kW) loads.

I'd also suggest that you check the Battery settings in the inverter. If the inverter cannot communicate with the BMS, then I wonder what settings he has put there...