Stanley

Are you sure the surge current that trips the BMS isn't just when you connect the inverter to the battery for the first time? The inverter will have a fairly large DC bus capacitance which will cause a big current spike when you connect it to the battery. Turning pylontech batteries on with the Inverter connected will also cause a trip no-matter how many batteries you have because the Master battery turns on first and will trip before the others have started. The solution to this problem is to add a pre-charge circuit. The simplest way is to use a removable fuse between the battery and the Inverter (you must have a fuse anyway, so why not use a cartridge fuse or similar fuse that is easy to remove and insert) and then wire an normally-open momentary contact push button in series with a resistor (I would say 47 Ohms, 20W or so should be ok) across the fuse holder. Then to start the inverter, begin with the fuse open, turn the battery on, then press and hold the push button for 10 seconds or so before closing the fuse. This will eliminate most of the current surge and prevent tripping the BMS.

Another sneaky one that could get you is lighting. If you don't already have LED lights everywhere, then switching to LED lights could reduce your nighttime consumption significantly. When we moved into our current home, the previous owners had put in 100W halogen lights all over for some reason. The first thing I did was replace them with LEDs.

I have never liked the 25mm^2 cables they supply so I have always doubled up on the cables that you get with Pylon batteries. However many batteries you stack, you will always have open connectors on the top and bottom battery, so I put a set of cables in both. If you refer to SANS10142-1, the maximum current for 25mm^2 cables in free air, laying horizontally is 146A, all other orientations or mounting methods have lower current ratings, so I would rather play it safe and use more / bigger cables.

That depends if the more expensive hair dryer uses a diode for the low power setting or not.
My wife has a "Dyson Supersonic Hair Dryer" which is quite expensive and our inverter has no problem with it on any setting.
It does have more than two temperature and speed settings which is also a giveaway that it is not just using a diode.
Edit: You could score some serious points with the wife by buying her one (J ust don't tell her it's to sort out the inverter issue XD )

I'm not sure if they published it yet, but I copied that text from an e-mail that was sent to us by Ryno van der Riet at the City of Cape Town.
This is the full text (minus the greeting and for some reason Table 1 is not being pasted):
Feedback as follows:
1.     Residential grid-tied SSEG and grid-tied hybrid SSEG:
a.    Generation size limits apply as described in the City of Cape Town’s  ‘Requirements for small scale embedded generation, Table 1’.

b.    Maximum Total Generation Capacity refers to the maximum active power capacity of the generator at the utility point of connection (POC). For PV systems in particular, this refers to the maximum active power generation capacity of the inverter as limited either by hardware, or by software settings at the POC, whilst the inverter rated power could be higher than the Maximum Total Generation Capacity.   
 
2.     Residential off-grid SSEG,  Passive standby UPS utilised as off-grid hybrid SSEG and PV Alternative Supply in terms of SANS 10142-1: 2017:
a.    Maximum battery charger power drawn from the utility shall not exceed the Maximum Total Generation Capacity limit as described in the City of Cape Town’s ‘Requirements for small scale embedded generation, Table 1’.
b.    The inverter rated power could be higher than the Maximum Total Generation Capacity limit.    
 
Best,

Ryno van der Riet
Head: Protection & Telecoms
Energy and Climate Change
Bloemhof Centre, Bloemhof Street, Bellville
 

If they are using CTs, then if you know the CT ratio you can easily calculate the current in the secondary for a particular primary current.

CTs and Hall-effect sensors are 2 completely different things, although both are used for measuring current. CTs are passive devices (they really are just transformers) where the current in the secondary (the only winding on the CT) is proportional to the current in the primary (the conductor through the middle). This makes the CT a current source. In order to measure the current, the measuring device will usually have a burden resistor at the measuring end so that the voltage across the burden resistor is proportional to the current and will not be affected in any way by cable length etc. as any other voltage drops or resistance in the circuit will have no effect on the measurement. The burden resistor is usually quite a low resistance (often a fraction of an ohm) meaning it is very difficult for noise to cause a measurable voltage across the burden resistor. Of course the design of the measuring circuit is also important to make sure it get's rid of / can handle common mode noise. Putting the burden resistor at the CT instead of in the inverter / measuring device would of course negate the benefit of the CT being a current source.
Hall-effect sensors are active devices (they have electronics in them that need to be powered) that measure current using the hall-effect, which means that they can measure both AC and DC current (unlike CTs which can only measure AC). Since they are active devices, their output depends on the circuit design. You can get these with a whole range of output options including current outputs (although this is most likely done using an opamp in a current source configuration).
So I guess it depends on what the Sunsynk uses to measure the current. Is it a CT or a hall-effect sensor?

CTs are current sources and therefore the signal is very immune to noise. You shouldn't see any interference if you run the cables in the same conduit as the AC.

For batteries, I can recommend Freedom Won, Solar MD and Pylontech.
Pylontech is nice because it's modular and you can easily add more later.
Solar MD also allows adding more quite easily but they are wall mounted or their own proprietary rack mount form factor (so must use their rack)
Freedom Won is floor standing and look quite pretty, you can also add more but only of the same capacity so if you start big you can't add just a little bit more later.

An overload is a load that is greater than the inverter's rating. Depending on how much the inverter is overloaded it may be able to handle it for a while. A short-circuit on the other hand is a bit more difficult to define, and is just a very low impedance. A short circuit (much like an overload) depends on what is supplying the power. You would agree that a 10kW load would be an overload for a 5kW inverter, but not for a 10kW inverter. Similarly a 20kW load might be so much of an overload for a 5kW inverter that it's over-current protection kicks in to protect it from blowing up. This would essentially be seen as a short circuit to the 5kW inverter, while a 10kW inverter would just see it as an overload. Now in the case of a power failure, we are talking about a load of hundreds of kW or even MW. Let's say for the sake of this discussion that your inverter is trying to power a load of 100kW on one phase of the supply. The impedance of that would be (230^2 / 100000) = 0.529 Ohms (Since P = V^2 / R so R = V^2 / P)
Now I don't know about you, but I would regard an impedance of 0.529 Ohms to be pretty much a short circuit, but again that is subjective because a 100kW inverter would be happy supplying that load. All I was trying to do earlier was describe what happens during a power failure, and why certain things happen. i.e. Why the inverter output collapses to 0V before it can disconnect from the grid. I don't think any of us have inverters capable of supplying hundreds of kW to keep the grid up during a power failure. Although it could become a problem if enough people in a small area have inverters, as they could collectively keep the grid going which is one of the reasons why the anti-islanding protection in inverters has to be very good.

Another sneaky one that could get you is lighting. If you don't already have LED lights everywhere, then switching to LED lights could reduce your nighttime consumption significantly. When we moved into our current home, the previous owners had put in 100W halogen lights all over for some reason. The first thing I did was replace them with LEDs.

Another sneaky one that could get you is lighting. If you don't already have LED lights everywhere, then switching to LED lights could reduce your nighttime consumption significantly. When we moved into our current home, the previous owners had put in 100W halogen lights all over for some reason. The first thing I did was replace them with LEDs.

An overload is a load that is greater than the inverter's rating. Depending on how much the inverter is overloaded it may be able to handle it for a while. A short-circuit on the other hand is a bit more difficult to define, and is just a very low impedance. A short circuit (much like an overload) depends on what is supplying the power. You would agree that a 10kW load would be an overload for a 5kW inverter, but not for a 10kW inverter. Similarly a 20kW load might be so much of an overload for a 5kW inverter that it's over-current protection kicks in to protect it from blowing up. This would essentially be seen as a short circuit to the 5kW inverter, while a 10kW inverter would just see it as an overload. Now in the case of a power failure, we are talking about a load of hundreds of kW or even MW. Let's say for the sake of this discussion that your inverter is trying to power a load of 100kW on one phase of the supply. The impedance of that would be (230^2 / 100000) = 0.529 Ohms (Since P = V^2 / R so R = V^2 / P)
Now I don't know about you, but I would regard an impedance of 0.529 Ohms to be pretty much a short circuit, but again that is subjective because a 100kW inverter would be happy supplying that load. All I was trying to do earlier was describe what happens during a power failure, and why certain things happen. i.e. Why the inverter output collapses to 0V before it can disconnect from the grid. I don't think any of us have inverters capable of supplying hundreds of kW to keep the grid up during a power failure. Although it could become a problem if enough people in a small area have inverters, as they could collectively keep the grid going which is one of the reasons why the anti-islanding protection in inverters has to be very good.

No, a small change in frequency wouldn't make the dimmers switch on or off. It may cause the brightness to change briefly though.
When the grid fails, it takes time for the inverter to realize that the grid is gone and time for it's contactor / relay etc. to open and disconnect it from the grid.
In that time. the grid voltage has dropped to 0 very quickly, this is the first transient. Then the inverter needs to take over, ramping up it's voltage very quickly which would be the 2nd transient. Note that this is different from just turning off the circuit breaker supplying the inverter because during an actual power failure (i.e. Load shedding etc.) the supply to your entire neighborhood has been disconnected, so your inverter which is connected to the grid is essentially trying to supply the whole neighborhood for a few mS. So this appears as a short circuit very briefly until the contactor or relay can open to disconnect it from the grid. During that time the load will see the voltage drop to 0 and then climb very quickly again. This dip is usually about 20mS, but may be a bit more or less depending on the inverter and how it detects a grid loss and also what it uses as it's disconnecting device.
For off-grid inverters where the inverter isn't actually inverting while the grid is present you will see something similar, but this will happen even if you just turn off the breaker supplying the inverter and not only during a real power outage. This is because the inverter also needs to detect the grid loss then disconnect from the grid and then start inverting. (A true hybrid inverter is always inverting even while the grid is present, so the problem is only that the grid becomes a short circuit when the power fails)

No, a small change in frequency wouldn't make the dimmers switch on or off. It may cause the brightness to change briefly though.
When the grid fails, it takes time for the inverter to realize that the grid is gone and time for it's contactor / relay etc. to open and disconnect it from the grid.
In that time. the grid voltage has dropped to 0 very quickly, this is the first transient. Then the inverter needs to take over, ramping up it's voltage very quickly which would be the 2nd transient. Note that this is different from just turning off the circuit breaker supplying the inverter because during an actual power failure (i.e. Load shedding etc.) the supply to your entire neighborhood has been disconnected, so your inverter which is connected to the grid is essentially trying to supply the whole neighborhood for a few mS. So this appears as a short circuit very briefly until the contactor or relay can open to disconnect it from the grid. During that time the load will see the voltage drop to 0 and then climb very quickly again. This dip is usually about 20mS, but may be a bit more or less depending on the inverter and how it detects a grid loss and also what it uses as it's disconnecting device.
For off-grid inverters where the inverter isn't actually inverting while the grid is present you will see something similar, but this will happen even if you just turn off the breaker supplying the inverter and not only during a real power outage. This is because the inverter also needs to detect the grid loss then disconnect from the grid and then start inverting. (A true hybrid inverter is always inverting even while the grid is present, so the problem is only that the grid becomes a short circuit when the power fails)

Dimmers can be affected in a couple of ways. Most dimmers look for the zero-crossings of the AC signal and use that for their timing. Then depending on if they are leading edge or trailing edge dimmers, they either wait some time after the zero-crossing before turning on or they turn on at the zero-crossing and then wait some time before turning off. Either way, distortion of the AC waveform can cause the zero-crossing detection to trigger a little earlier or later on different cycles, making the brightness fluctuate. So if the brightness was constantly changing then it is most likely caused by some distortion when the hair dryer was on.
Another possibility with bell-press dimmers (the ones that you turn on and off by pressing the same button that you hold to change the brightness) is that they have a small capacitor between live and the button input and high frequency noise can go through that capacitor making the dimmer think that the button has been pressed briefly. This will cause the dimmer to turn on and off. So if it was turning on and off then it is most likely caused by high frequency noise.
Hair dryers are particularly nasty if you use them on their half power or half speed setting, because most hair dryers use a diode rectifier for the half speed or half power setting, which means they only draw current for one half of the AC wave. This causes transformers to saturate and then the waveform can get quite badly distorted.

Dimmers can be affected in a couple of ways. Most dimmers look for the zero-crossings of the AC signal and use that for their timing. Then depending on if they are leading edge or trailing edge dimmers, they either wait some time after the zero-crossing before turning on or they turn on at the zero-crossing and then wait some time before turning off. Either way, distortion of the AC waveform can cause the zero-crossing detection to trigger a little earlier or later on different cycles, making the brightness fluctuate. So if the brightness was constantly changing then it is most likely caused by some distortion when the hair dryer was on.
Another possibility with bell-press dimmers (the ones that you turn on and off by pressing the same button that you hold to change the brightness) is that they have a small capacitor between live and the button input and high frequency noise can go through that capacitor making the dimmer think that the button has been pressed briefly. This will cause the dimmer to turn on and off. So if it was turning on and off then it is most likely caused by high frequency noise.
Hair dryers are particularly nasty if you use them on their half power or half speed setting, because most hair dryers use a diode rectifier for the half speed or half power setting, which means they only draw current for one half of the AC wave. This causes transformers to saturate and then the waveform can get quite badly distorted.

That battery voltage curve is typical of a lithium battery being completely discharged. i.e. The voltage remains pretty flat until the battery is close to empty and then the voltage starts dropping rapidly. This should not happen at 50%SOC. How are you reading SOC? i.e. Do you have comms to the battery itself or are you using a 3rd party device like a Victron BMV to measure energy in and out? Do you have more than 1 battery in parallel? If you have 2 for example, then maybe there is a bad connection on 1 of them so you are only using 1 of the batteries and therefore only have half the capacity available (hence being empty at 50%)

I have not used ICC, so I'm not certain how this works, but if it can read SOC from the battery and use that to control the inverter then yes, that sounds about right.

That depends if the more expensive hair dryer uses a diode for the low power setting or not.
My wife has a "Dyson Supersonic Hair Dryer" which is quite expensive and our inverter has no problem with it on any setting.
It does have more than two temperature and speed settings which is also a giveaway that it is not just using a diode.
Edit: You could score some serious points with the wife by buying her one (J ust don't tell her it's to sort out the inverter issue XD )

That depends if the more expensive hair dryer uses a diode for the low power setting or not.
My wife has a "Dyson Supersonic Hair Dryer" which is quite expensive and our inverter has no problem with it on any setting.
It does have more than two temperature and speed settings which is also a giveaway that it is not just using a diode.
Edit: You could score some serious points with the wife by buying her one (J ust don't tell her it's to sort out the inverter issue XD )

That depends if the more expensive hair dryer uses a diode for the low power setting or not.
My wife has a "Dyson Supersonic Hair Dryer" which is quite expensive and our inverter has no problem with it on any setting.
It does have more than two temperature and speed settings which is also a giveaway that it is not just using a diode.
Edit: You could score some serious points with the wife by buying her one (J ust don't tell her it's to sort out the inverter issue XD )

LEM makes a very large range of hall-effect sensors with different measuring ranges and supply voltages etc.
https://www.lem.com/en
R.S Components does stock quite a few of their products (for some reason they put them in the same category as the current transformers).
Here is a link to one of them as an example:
https://za.rs-online.com/web/p/current-transformers/0497182/

The switch with feedback to the inverter is the internal relay or contactor that the inverter uses to connect the load to the grid when in standby mode.
(This is only applicable for Passive standby UPS used as off-grid SSEG)
The inverter must know the state of this switch (not just based on what it wants the switch to do, because switches can become stuck or welded closed) so that it can never try to power the load from the inverter while the load is powered by the grid.
The Hager changeover switch is just a manual external changeover switch (It is good to have this in your drawing when submitting your application as the people approving them don't know the difference, they just look for a changeover so make sure to label it as such in the drawing)

Generally you will have at least 2 Neutral points (more if you have more than one earth leakage protection device). One for the neutral before the earth leakage protection and one for after. If you mix them up you will have your earth leakage breaker constantly tripping.