Calvin

The OP has a Sunsynk and batteries. That allows him to limit the power drawn from the generator. Not all inverters have that ability.

Hi
I do not know if this is the correct place to post this topic.
I purchased a 6Kw generator many years ago before I installed an 8Kw inverter. I bought two 20l metal jerry cans and three 25l treated(red) plastic petrol storage cans.
The metal jerry cans sometimes leak at the seal of the spout. I have since 3D printed thicker seals and have no more problems. The metal cans can also rust as there is a small amount of water in the petrol and can separate when stored.
A bigger problem was with the treated plastic containers. I filled the containers and sealed them for when needed. I had stored them for quite a long time and when it came to using the fuel this is what I found.
The plastic caps on all the containers were broken (cracked) and needed to be replaced. After some thought, I came to this conclusion. The full cans were sealed in the winter when it was cool and when the weather heated up the pressure from the petrol heating up broke the caps. I also lost a lot of fuel through evaporation. I now store the petrol in the treated plastic can and slightly loosen the small breather cap on the opposite side of the spout.
I know that you should not store petrol for more than a year and now fill my vehicle with the stored fuel after 6 months and put fresh fuel in the cans. I also do not fill all the cans.

https://www.hellopeter.com/infinity-group-companies
Don't think I can trust them with my money

Hi
Recently after having a power failure with being rainy and overcast the previous day, I woke up to find my house without power despite having an 8Kw Sunsynk inverter with 500ah batteries.  It was 5:30 am so I took my torch and investigated only to find I had completely depleted my batteries.
I had recently coupled my geyser to the grid from gas as I had added more PV panels and had ample power (9000w) to use. I also have to power a borehole pump and aux pump from the JoJo tank.
I have a 6Kw petrol generator coupled to the inverter which can be switched to the grid or aux (gen) input without an auto-start. I proceeded to start the generator and switched the generator to the grid input, only to find that this did not work. I was very annoyed and then switched over to the aux (gen) input to find that this also did not work.
I thought I had it all sorted when I installed my system and bragged about my installation, however to my regret, I got a wake-up call.
After checking the generator voltage indicator, I saw it did not show any voltage. I was convinced that this was a generator fault and did not try to put the generator in the bypass mode. I proceeded to switch all the large loads off (borehole pump, switch the geyser to gas, and only use the gas hob). After taking my grandchildren to school the sun was up and my PV panels did power the house to my relief and not to get an earful from my wife.
After getting help (4 guys) to remove the generator (100kg) from its bricked housing I started my fault-finding. To my surprise, only the mechanical voltmeter was broken.
 What now as it was not the generator?
I took the time to clean the generator and put it back in place with help. I did all the switchovers again only to find it still did not work.
Just to mention that I have spent more than 40 years working with electronics and instrumentation.
One of the most important things I have learned over the years is to go back to read and follow the instructions. 
This is what I did. I also followed up with videos from Sunsynk and this was the result.
1.       The biggest problem was the frequency which was 54.6 hz.  I had to adjust the frequency on the generator under load as close to 50hz as possible. This can be done by adjusting the screw on the linkage arm of the carburetor which will correct the speed and frequency.
2.       The frequency band on the inverter also needed to be adjusted for a larger band to accommodate the frequent load changes of the generator.
3.       There are other settings as well that affect the inverter if the generator is grid-coupled or aux-coupled. It also matters if you use timed settings as this will override the start and stop charging settings of the battery. The grid-tied generator to the inverter is much less forgiving to frequency change.
4.       The charging of the batteries from the generator needs to be set lower on a grid-tied generator.  if you set it too high there will be no power for the household load. The best Installation is to have a generator twice the power of the inverter so that it can charge the batteries without affecting the load. This is always not possible so be sure you have adjusted the settings for the size of the generator.
5.       If you have an electrician do the installation, make sure that he has done all the checks and has tested it before it is signed off. It will always be up to the owner to read the instructions so you can be sure the electrician has done all the tests and correct settings or else when the generator is needed it might fail and you might need to pay again to have it set correctly.
6.       Finally, the earthing of the generator.
A.      If it is coupled in the grid mode, the neutral has to be coupled to the earth as there is no link to neutral for a series earth leakage (RCD) to work if the mains neutral is decoupled.
B.      When the generator is coupled to the aux (gen) input the inverter should already have an earth bond relay installed to protect the system with the earth leakage (RCD) in series when the neutral is decoupled from the mains in the inverter during a power failure. I use an automotive 12vdc relay which can handle 30a.
In a complete circuit, there must only be one earth-neutral bond.
I see many installers fitting a permanent bond between earth and neutral on the inverter. This is illegal as now there are two earth-neural bonds when the mains power is present. (one in the inverter and one in the DB. Box).
I find it pure laziness that an electrician cannot use a relay to couple the neutral to earth even if the inverter does not provide a signal or voltage output as he can use the 220vac mains power input to the inverter as the signal to connect the bond.
NB: THE earth-neural bond must be the bond of the neutral on the output of the inverter to earth and not the neutral input from the Mains Power input.
 
The earth-neutral bond done on the Mains input is only done when the Mains Power is disconnected (live and neutral) and a Generator is used as the Mains Power input.
All is now good and working as it should.
I hope this will help someone who wants to couple a generator to an inverter and avoid the same problems and frustrations I have gone through.

Wouldn't look a gift horse in the mouth. Just take the generator.
Is this an off-grid inverter installation, or are you catering for a complete and utter collapse of Eskom? If so, then yes, by all means, hook up the generator and install additional panels, for the gloomy Cape weather.
But what about if you are connected to the grid? Personal 2c worth, to each his own. In that case I'd say simply... do nothing. Considering the amount of battery power you have relative to your daily needs - between 1.7 to 2.5 times your daily consumption - I'd just run down to a 50% battery reserve for loadshedding, and otherwise once you reach that 50%, switch to grid.
I just don't think the other options are worth it relatively speaking. Instead of running the generator at say R10 per kWh, you could just as well wait for loadshedding to be over and charge batteries from the grid.
Also, you've already got enough panels connected to cater for normal sunny days and even partly cloudy days most of the time. The extra 2 panels, if it's 1kW of nameplate capacity you're adding, then during the worst weather they'd be generating maybe 20-30% of what they are rated for, and other parts of the year they'd be superfluous to your needs. For maybe, say 30 really miserable days a year that would be just 1-2 extra kWh roughly available on the bad days. Call it R100-R200 return on investment per year, very roughly thumbsucked. Again, may as well just ensure you keep some reserve battery capacity, and run and charge from grid around the loadshedding slots, than incur the cost of the panels for a meagre additional benefit.

I have some US2000, US2000C and US3000B. For all those, the SOH and cycle count are calculated with a simple formula (by the BMS)
Cycle count goes up by 1 for every 50Ah discharged on US2000 (74Ah for US3000)
SOH goes down by 1% for each 100 completed cycles.
For a stack of Pylons the same logic applies - simply use total capacity and discharge.
So, @Youda , your 8 x US3000B had a total of 3890 cycles on 30 Jan. Expect the SOH to drop to 95 any day now when the stack total gets to 4000 cycles.
A note of caution: this is based on observations on my batteries, all of which have been treated very gently. They are all at about 700 cycles.
I have one data point from an older US2000 that leads me to believe that the formula changes at 1000 cycles/90% SOH. The slope thereafter seems to be 0.6% SOH per 100 cycles (or 1% for each 166.7 cycles)- that will nicely get it to 60% at 6000 cycles that Pylon claims.
The bad news from all of this: the Pylon's SOH is not an indication of how well the battery has been treated. It is simply an estimate of remaining capacity based purely on total cycles. This is very disappointing given that they have a very sophisticated chip (TI BQ34z100) in the BMS whose sole purpose is to accurately estimate SOH and SOC based on real measurements.

I have some US2000, US2000C and US3000B. For all those, the SOH and cycle count are calculated with a simple formula (by the BMS)
Cycle count goes up by 1 for every 50Ah discharged on US2000 (74Ah for US3000)
SOH goes down by 1% for each 100 completed cycles.
For a stack of Pylons the same logic applies - simply use total capacity and discharge.
So, @Youda , your 8 x US3000B had a total of 3890 cycles on 30 Jan. Expect the SOH to drop to 95 any day now when the stack total gets to 4000 cycles.
A note of caution: this is based on observations on my batteries, all of which have been treated very gently. They are all at about 700 cycles.
I have one data point from an older US2000 that leads me to believe that the formula changes at 1000 cycles/90% SOH. The slope thereafter seems to be 0.6% SOH per 100 cycles (or 1% for each 166.7 cycles)- that will nicely get it to 60% at 6000 cycles that Pylon claims.
The bad news from all of this: the Pylon's SOH is not an indication of how well the battery has been treated. It is simply an estimate of remaining capacity based purely on total cycles. This is very disappointing given that they have a very sophisticated chip (TI BQ34z100) in the BMS whose sole purpose is to accurately estimate SOH and SOC based on real measurements.

Seems there is a paragraph missing:
22. Homeflex penalties:
The following penalties shall apply to each POD:
1. Per month:
1.1 A proportional penalty each and every time that Eskom fails to deliver Power at the POD.
1.2 For each and every failure - forfeit the R/POD/day rate in totality.
1.3 Pay additional penalties in relation to the Stage of Load Shedding: E.g. Stage 6 - applicable penalty is 6 x R/POD/day rate.
1.4 Penalties may not be used to offset Usage at the POD.
2. Per Year:
2.1 Should the Utility fail to provide a 24 x 7 x 52 service at the POD, it will be incur additional penalties as follows:
2.1.1 R10,000 if any failure occurs during this period.
2.1.2 This amount is to compensate for long term effects of any loadshedding, e.g. replacement of electrical appliances, inconvenience, insurance premiums, additional expenses incurred at the POD by the home owner to ensure a continues supply of power.
2.1.2 Penalties may not be used to offset Usage at the POD.
3. No excuse performance will be tolerated. E.g. generation, distribution, force majure, Regional & National Government, etc.

The label in the picture shows manufactured in 2020, but you still say age is 2 years?  A mistake I assume, as the US3000B was discontinued in 2021.
Also, has it been topped up in the meantime?  Leaving a battery without charging for 5 years may well ruin the cells due to self-discharge...

Pylons are notoriously sensitive to how well they are treated - you will make your life a lot easier selling these if you connect a PC to the console port and extract exact cycle data and logs via BatteryView.  That way people will know what they are buying, and you will be able to get a fair price.  Failing that, I suspect that potential buyers would assume the worst.
2 other points:
The picture you show is a US3000B, not a US3000C.  They are significantly different.
These are now available brand new for R15k. Pylon US3000C 3.5kWh Li-Ion Solar Battery (excl. brackets)
 

Keep the inverter in a cool and ventilated place.
Also, protect it from collecting excessive amounts of dust.
Do not put high inductive loads on it. (IE: do not put 5kVA motor on a 5kVA inverter)
Follow installation instructions, especially when comes to proper grounding, SPDs, input voltages.
 
IMHO, there's not much you can do proactively, if you don't want to crack the box open and replace one third of the components in advance. Which, to be honest, nullifies advantage of a cheap box.

Be very careful with making this decision. Note below, that Nersa has reportedly now approved the restructuring of Eskom's tariffs into a fixed fee and time-of-use fees, with some other changes. You cannot base your decisions & payback calculations on the people that installed solar before you because the rules of the game have just changed, and we'll only see how the dice land from 1 July onwards.
Nersa approves restructuring of Eskom tariffs - Moneyweb
That being said, if you go about it smartly, know your needs, choose and use your system wisely, it's surely possible to drop your costs now and especially in the long run. If you just slap something in without proper analysis, you could also be wasting lots of money.

It seems to me that both Pylontech and Voltronics are to blame.  Pylontech for requesting voltages that are too high (in the real world, where 2nd rate manufacturers implement poor control algorithms that overshoot) and Voltronics for being such a 2nd rate inverter manufacturer.
 
You will probably find the other batteries are all in advanced stages of degradation.  Consider setting battery type to USE and max charge voltage to the lowest that still gets you to 100% - my Pylons work well at 52.6V.
Also consider setting the float voltage down to about 50.5V.  It will mean that your SOC will drop to about 99.5% as soon as the batteries are full, but it will greatly enhance their lifespan.
Of course using an Axpert means that your inverter cannot be relied on to correctly switch to float, unless you are running a version of @Coulomb's patched firmware.

You may be able to do better than that: if you run the pwrsys command, the field "System RC" is the system remaining capacity and the field "System FCC" is the Full Charge Capacity.  The more accurate SOC is ((double)SystemRC * 100 / SystemFCC).  The reported SOC is that number, truncated to the integer.
This applies to the whole stack irrespective of the number of batteries in it.
 
Have you found a good source of load-shedding schedules, ideally via an API rather than scraping?  I am aware of https://loadshedding.eskom.co.za/LoadShedding/GetStatus but am looking for actual schedules.
 
Nice system BTW.  And there I thought that I was a control freak... 😆
 

Just a note for the curious:
Ports A/CAN and B/RS485 on the US3000C are having both protocols in each port. So the A is technically CAN+RS485, B is CAN+RS485 too. Daisy chaining of multiple "piles" together runs over RS485 protocol, the conversion to CAN protocol is done by the LV-HUB in the last step. Daisy chaining of individual bricks within a single pile uses RS485 protocol too, but this time via LinkPort0 and 1 ports.  

 

That really depends on the inverter.
If the inverter wants RS485 as BMS input, you can skip the LV-HUB in the last step. That's the case for Axperts, for example.
If the inverter wants CAN BUS as BMS input, you need to supply CAN. That's the case of Victron, etc.
On top of it, there another catch: with the RS485 the inverter firmware has to support not just the BMS protocol itself, but also a total number of piles and Pylontech batteries connected. AFAIK, some inverters with RS485 BMS IO support just 2 piles of the batteries. Not being able to address more.
With CAN the number of batteries and piles does not matter. Once the inverter supports CAN for BMS, you can connect all the batteries and piles you have.
 

You may need to be more aggressive with your pricing.
Right here on PowerForum Store you can get a Deyness 14.3 kWh LFP with 10 year warranty for R37 375.
Dyness PowerBrick 14.336kWh Lithium Battery
 

You can use an online calculator to find the clamping force (Bolt Torque, Axial Clamp Force, Bolt Diameter Calculator)
That will tell you that 4 x 8mm screws tightened to a torque of 1.2Nm will generate about 3000N (about 300kg force)

Well guys, I would not blindly trust any voltage measurement that is:
- measured by the inverter itself
- performed while the inverter is still connected to the batteries and AC loads are ON, panels are ON.
Who could be 100% sure that the voltage fluctuation is produced by the battery, not by the inverter?
My 2 cents...

Agree, that's why I'd like to see the bms logs.

@Coulomb You are right - I should have qualified my statement better.  It was meant in the context of the conversation, not as a generalisation.
 
All true, but not pertinent: we are talking about almost fully charged LFP with negligible current. (The voltage increased by 0.8V in 5 minutes.)
 
 

You may need to be more aggressive with your pricing.
Right here on PowerForum Store you can get a Deyness 14.3 kWh LFP with 10 year warranty for R37 375.
Dyness PowerBrick 14.336kWh Lithium Battery
 

Technically the inverter is not sending voltage, but it's sending current. It's so called "CC mode". The current is being split between all the batteries based on their internal resistance, interconnection resistance and willingness to accept charge that changes with SOC of the individual cells. For the same voltage, different batteries will have different charging current. The 53,5V is the voltage value that the inverter is looking for to stop sending current (stop charging).
Some of the events that signalize end of charging (CC mode) and transfer to the CV mode:
If the battery reports 53,5V the inverter stops charging, even if the cells would still accept current. If the cells stops accepting current, the charging is finished. This might occur even before the cells reach 53,5V. If the BMS reports 100% SOC, inverter will stop charging. If the BMS reports "Advise Charge = 0A", inverter will stop charging. If the BMS reports one of the many possible Errors and Alarms, inverter will stop charging. Most of the time CMOS will be activated by the BMS, so even if the inverter would still continue with the charging, the actual current will be zero amps. Pylontech BMS is really doing nothing to the current that is flowing from the inverter. It has two protective MOSFETs (DMOS and CMOS), that are being operated in the ON/OFF state based on alarms. No analog current modulation feature is in the BMS.

Also, it is important to understand that physically, there is nothing like 100% SOC for the cell.
A LFP cell is just like an air-filled birthday party balloon:
When is the balloon 100% full? Is it the state when you blow another air molecule into it and it pops? If so, how does it depend on the balloon's temperature? If that 100% full mark is somewhere lower, where more additional molecules would safely fit inside, can I blow some more air into the balloon? How much? The "curse" of LFP is that they are so energy efficient that you can damage them even with just 1mA of charging current, if applied for a long time. With Lead-Acid batteries that would be absolutely no problem, but LFP stores lithium ions in the hard 3D lattice. If there's no more space for incoming ions, the lattice will crush and gas-mix of O2+CO2+phosphate will be produced.
And that is the reason, why some cells are swollen. Either they had manufacturing defect (most of the time it's the the separator failure), or something was hitting them with just a few miliamps of current for a long time, so the lattice started to break.
 
Yes, it would be great to have a BMS that can perform sophisticated monitoring of the cells, but in reality all the BMS-es are just measuring temperature, voltage, current and doing time-based integration of Coulombs in order to "guess" SOC. But keep in mind that more complicated electronic device is, more likely will it fail. Not to mention that it will cost more, consume more energy and produce more heat.
While the Pylontech BMS is far from being perfect, the solution is not to improve and over-engineer the BMS itself, but to configure whole solar system in a way that the margin between "balloon full" and "balloon popped" states will be reasonably wide and safe.
 

This is normal. As the cells in a module are reaching full charge, their ability to receive charge drops gradually. Therefore the charging current drops too.
For example, here's the charging current of 8xUS3000 in one of my stacks:

The gradual drop of the current is caused by the cells, it's not something that BMS or Inverter does. For each battery in the stack this curve will be slightly shifted in time. That's because each battery has a slightly different charge, therefore slightly different ablility to receive current. Exactly as shown on your BV screenshots. You can observe this even by just looking at the LED bars of the individual batteries - some of them will be fully charged already (LED bar goes off) while the others will still being charged (LED bar with one blinking LED).
Once again, it's pretty normal that you see a different amps for each battery in the stack and the BMS/Inverter has nothing to do with that.
 
Yes, the BMS IS able to tell the inverter what to do, but the charging information is sent for the whole stack, not for individual batteries. For example, this is the info, that BMS sends via CAN BUS during charging of the above mentioned stack of 8 batteries:
charge with 300A max charge with 120A max charge with 100A max charge with 90A max charge with 0A max
 
 
Yes, some of the batteries might experience manufacturing defects, resulting in premature damage. That's what warranty is for. But the examples shown in this thread, where 10+ batteries "blown" at once are not that case.