PierreJ

The fuses are there to protect the cables. With the current configuration there are several fault conditions that can cause the 120A current limit in any of the cables to be exceeded, so if the electrician is paying attention then a 160A fuse should fail the CoC inspection. If this setup was to code then it would also be legal to connect all the plug circuits in your DB board directly to a single 60A breaker, with the argument that the total current carrying capacity of all the circuits exceed 60A. This is a ridiculous example, but it illustrates the point: Every individual conductor must be protected against overcurrent.

The Pylontech cables are AWG4 (about 21mm^2), which is generously rated at 120A max by Pylontech. If I am correct in assuming that you're using the standard Pylontech cables, then your fuses may not be larger than 120A.

Since the current for both inverters pass through a single fuse on the left configuration you'll need fuses rated for twice the current of the right configuration. This also means all the battery cables for the left-hand configuration have to be twice as thick as they have to be for the right-hand configuration. As long as the cables match the fuses then there's nothing wrong with the left-hand configuration, but I suspect that is not the case and that may be the actual reason why the installer wants to change it to the right-hand configuration.

Mine recently did the same: I also thought it very strange that the neutral pole would have experienced a surge and not the live, so I figured there's a very high chance it's just the indicator light that blew. I replaced it just to be safe, but now that I see another case of this happening I'm again scratching my head wondering what's really going on here.

Pylontech is sending out the us2000B_Plus_V3.4_Crc.bin firmware for older US2000B plus batteries as well, so I suspect that they might be allowing the 95% discharge even on the older batteries. Alternatively, the firmware could be smart and detect the minimum SoC from the serial number. I have never run any of my batteries down below 15% SoC, so I do not know. It could have been a mistake on their part, but since I only gave them the serial number for the battery (I didn't mention the model number) in my firmware request I reckon it's not likely.

Yes, that would be a "Passive standby UPS utilised as off-grid hybrid SSEG". This makes the wiring less of a chore since you don't have to split out a new DB for your essential loads, but it does leave your heavy loads (e.g. oven and geyser) on the output of the inverter. Consequently you may need to shell out for two or more units in parallel.

There's plenty of confusion around this topic, and perhaps at some stage even in the ranks of CoCT. However, if you look at the CoCT SSEG webpage you will note that there's only two models: Grid-tied and off-grid. "Grid-tied" is a standard term used to indicate that the inverter synchronises with the utility grid and is capable of injecting power back onto it. Everything else is off-grid. If you look at the declaration form for off-grid systems you will note that there are several options listed: • Passive standby UPS utilised as off-grid hybrid SSEG • SSEG alternative supply in terms of SANS 10142-1: 2017 - The wiring of premises • Electrically separated off-grid SSEG installations that is not interlocked with the utility electricity grid as a switched alternative Note that only the last option is "electrically separated".

Axpert inverters are not grid-tied, so the approved inverter list does not apply. Your install is classified as a "Passive standby UPS utilised as off-grid hybrid SSEG". You don't need an engineer to sign off on the system, but you will need an electrical CoC, and if there is a changeover switch then you'll need to attach a test report for that. The form you need to fill out and the related info is available here: https://www.capetown.gov.za/City-Connect/Apply/Municipal-services/Electricity/apply-for-authorisation-to-install-a-small-scale-embedded-generation-system You are allowed a maximum battery charging current equal to 25% of your main breaker (i.e. 15A AC), but I don't believe a breaker is required for that if you can limit it in software. Because your solar is "off-grid" it doesn't really matter how many panels you have.

I bought 5 US2000B batteries in March of last year. Two of them have since failed and were swapped out under warranty. The service from Pylontech was excellent, and the swapout process was painless in both instances. However, it is a bit concerning when you have a 40% failure rate within one year. I am hoping this was just a bad batch, and my experience is not indicative of the reliability one can expect from Pylontech batteries in general.

Panels in different orientations in parallel is not a problem. If they were in series then that would have been a mistake. See the attached case study for an explanation. east-west-solar-paper.pdf

1) Disconnect the controller from the isolator and connect it to the inverter output instead (via a breaker in the essential loads DB and a new additional isolator next to the controller). 2) Connect the geyser output of the controller to a relay that you use to switch the live coming from the grid isolator. 3) Connect the switched live coming from the relay and the neutral coming from the grid isolator to the element.

I see the H1 (geyser) relay has a 10A current limit, so I reckon you'll probably find there's already an external relay for the element that you can reuse.

I would move everything except the element to the essential loads output of the inverter - the element remains connected directly to the live and neutral from the grid. The geyser output of the controller I would connect to a 230V relay (or contactor) that switches the live wire going to the element. Make sure that the contactor or relay you use is sized appropriately. I would go for overkill, in case someone installs a higher powered element in future. I would also size the breaker from the essential loads DB to be just large enough to carry the controller and pump - in case some fool connects it directly to the geyser element (or worse, the grid) somewhere down the line. I'm paranoid, so I might even consider putting small fuses in the control wires going to the relay if I feel there is any chance that someone may confuse those wires with the wires coming from the grid and the wires going to the geyser. Note that this is not my area, so there may be regulatory requirements that I am not aware of.

Apparently there's another new model coming, the UP5000, which has a 4.8kWh capacity. It sounds like it will be even better bang for the buck than the US3000C. Link: https://segensolar.co.za/product/pylontech/storage-systems-pylontech/li-ion-battery-pack-storage-systems-pylontech/pylon-up5000-4-8kwh-li-ion-solar-battery-48v/

Yes, they will work. The US3000 series is the larger capacity version of the US2000: 50% larger storage capacity, as well as 50% greater maximum charge and discharge currents. They are otherwise the same, and you can even parallel the two different models together in the same battery stack if you want to. Pylontech compatibility info is here: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom Specifically note that you will need a GX Device (like a Cerbo) to be able to talk to the battery BMS, otherwise the battery will shut itself down after a while. Be aware that the CAN-bus pinout for the C-series batteries differs from the pinout of the B-series. You can make the cable up yourself using Cat5 cable and RJ45 jacks. The pinout is here: https://www.victronenergy.com/live/battery_compatibility:can-bus_bms-cable

That'll depend entirely on the hardware. Instead of guessing - why don't you ask the client to measure all their loads with a plug-in power meter so you know exactly what you're dealing with? If I was the client I would get the 5kVA Multi with a 4+ battery cabinet, but only two batteries initially. If I run into issues with the two batteries I would just add more. In case you haven't noticed, Pylontech has released a new model: The US2000C. The price seems to be about the same as the US2000B, but it allows a 95% DoD. The US3000C is the larger capacity model.

Let's do the worst case scenario math: Assuming a power factor of 0.5 for the LEDs (a capacitive load), it's 40VA per LED. If every computer has a screen, let's go for 200VA each. I have no idea how much power a CCTV system uses but it'll probably not be more than 100VA. That gives a total of 14 * 40 + 8 * 200 + 100 = 2260VA. The 3kVA Multi can sustain 2.4kW, so it will be able to carry the load. If you allow a 90% DoD on the US2000 batteries it'll give you just under two hours of runtime (when new). Given that the above estimates are on the pessimistic side I reckon it'll probably work, but there's very little room for future expansion. What if someone unexpectedly wants to run a laser printer or some other device that draws a couple of hundred watts?

Yes. According to Victron, you need a minimum of 4 x Pylontech batteries with a Multiplus II 5kVA. It's not only about the total energy storage, but also the startup currents of the inverter, peak currents, etc. See here: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom If you sacrifice the A/Cs then the energy storage capacity of two batteries should be sufficient to power your loads through loadshedding, however your battery bank would still be under-specced for the inverter. I have never tried to run my Multi with only two batteries, so I can't definitively tell you what issues (if any) you'll encounter. You could always start with two, and if you get DC ripple, BMS or other warnings then add more.

Thanks! The big issue I had when I designed my system is that I absolutely wanted more than 3.5kWp on the roof, yet had to stay under the City of Cape Town's 15A current limit. The Victron Multiplus is one of very few grid-tied inverters that allows you to limit the current flow between it and the grid connection, without crippling its output at the same time. Victron also has a good reputation for reliability, and if you add a GX Device it is exceptionally feature rich. As a DIYer my installation experience was very pleasant, and everything just worked out of the box. If you do hit a snag (one of my Pylontech batteries developed an issue some time after install), Victron tech support is top notch. The Victron system is very modular, which is mostly a plus, but if you add up the cost of all the components it can be quite expensive. Although the sticker on the Multiplus II says 5kVA, it is really a 4kW inverter if you look at the spec sheet. Those are the two negatives for me, but overall I am very happy with my purchase. I don't know much about the SunSynk other than what I've read on these forums. It certainly looks like great bang for the buck, but I don't think there's enough evidence yet to draw a conclusion on reliability.

Hi Hennie, I've currently got 16mm^2 cable and a 63A breaker between the combiner and MPPT. I have five strings so the maximum rated current is 5 x 11A = 55A. So far (touch wood) it hasn't tripped. The MPPT is rated at 70A input current, and given that I have space for another string on the roof, I was considering adding a 6th string... now I'm not sure that is a good idea anymore. Thanks for the warning.

Correct. The PylonTech cables are 25mm^2, rated at 120A. The recommended maximum charge and discharge current per US2000 battery is 25A, so if you have more than 4 in parallel and you're using them at the recommended maximum currents then you should use two pairs of their cables.

Hi David, I think you may have to sacrifice the air conditioners with only two batteries. If you insist on running the air conditioners during loadshedding then you would likely need to get a 5kVA Multi, in which case the recommended minimum number of Pylontech batteries is 4: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom You're going to have to purchase a GX Device, like a Cerbo, in order to communicate with the battery BMS. If you want to update the firmware of the Multi you will also need the MK3-USB cable: https://www.victronenergy.com/accessories/interface-mk3-usb. The Ve.Bus and battery communication cables use normal CAT5 cable, and you can make them up yourself - the pinouts are available on the Victron website. The breaker in your main DB is there to protect the cable, so the thickness of the cable will dictate the breaker: 30A for 4mm^2, 40A for 6mm^2, 50A for 10mm^2. The 5kVA Multi can pass through a maximum of 50A, so there is little point in going over 10mm^2. With the loads you listed above, 4mm^2 should be fine. Victron recommends 70mm^2 for the battery cables (good for 200A), however the cables that come with the Pylontech batteries are only 25mm^2 (120A). If you're not ever going to be using more than 4 batteries, and the batteries will be right next to the inverter then you can perhaps save some money and use 35mm^2 battery cable instead. The fuses in the DC isolator should match the cables, so 125A fuses would be appropriate. I don't know whether a changeover switch is a legal requirement, but it is certainly a good idea - if something goes wrong with your inverter setup you want to be able to use grid power while the issue is being addressed. While on the topic of legality: The Multiplus is a grid-tied inverter, so if you fall under City of Cape Town you technically have to apply for approval to install it. Surge protection is always a good idea, especially if you live in an area where an indirect lightning strike is a possibility. (Nothing will save the inverter from a direct strike.) There are photos in the original post of my essential loads DB. The layout is fairly standard, so if you copy that you should pass an electrical CoC inspection. Note the power indicator light at the bottom right, which is (as I understand the regulations) a requirement for a DB powered from multiple sources.

Hi Nigel, No, fortunately my situation is not that bad. I have a later hardware revision (v5), so it should not be affected by that particular issue. My Multi regularly throttles down to 3700W, but I've never seen it go lower. I wouldn't have taken much note of that if it wasn't for the temperature warnings. I've now set the "Limit Inverter Power" ESS setting to 4kW which will hopefully stop the overload warnings. Apparently the efficiency drops quite a lot under heavy load, so perhaps limiting it to 4kW will also lower the temperatures (I noticed that it will occasionally output 4.4kW for short periods of time).

Hi, I have a Multiplus II 5kVA unit (hardware revision 5, configured as part of an ESS system) that is reporting temperature warnings from time to time. Below is the screenshot of the VE.Bus Warnings and Alarms for the past 30 days: The highest ambient has ever been is 34C, but it hovers around 30C on most days. Airflow around the Multi is not obstructed: The warnings coincide with heavy loads either at the input or output side, and it running at capacity. I find that it derates to 3700W very soon after a heavy load (e.g. geyser) is switched on. I've never seen it derate lower than 3700W though. The fan turns on whenever the load exceeds about 1kW, which is most of the time. When the fan is blowing I can feel a slight draft at the intake vents at the bottom but the airflow at the top exhaust is barely perceptible. The top exhaust grille also feels very hot to the touch under load - almost too hot to touch, so I guess close to 60C. Something else that bothers me is the barrage of overload warnings being logged. The grid is (almost) always available, so there should be no reason for it to go into overload. Is what I'm seeing normal, or is something amiss? Thanks! P.S. Ignore the low battery and DC ripple warnings - the batteries were temporarily disconnected during a firmware update to revision 478 (the latest).

I reckon I might follow your lead and do something similar. While the heatsink has improved the situation with my SmartSolar (Interestingly I've never seen it throttle, even when it hit 82C), the Multiplus drops down to 3.7kW during the heat of the day. The outside case gets uncomfortably hot, so I can only imagine how hot it must be inside. I also get high temperature warnings in the VRM console from time to time. I can hear the fan inside it running at full tilt but I don't feel more than a very gentle draught at the bottom air vent. Is this normal? The temperature inside the scullery is about 3C above ambient, so short of installing an air conditioner I can't do much to improve it. (It is open to the rest of the house so it is not like all the heat gets trapped there.) Perhaps I should experiment with positioning a desk fan so it blows across both the Multiplus and SmartSolar. If that works well a permanent fan installation like yours is probably the way to go. It's a pity Victron don't yet have a Multiplus or Quattro that can sustain more than 4kW that is also approved by CoCT. The 5kVA Multiplus is slightly undersized for my needs, and I don't have enough space to install two in parallel.