epnaude

I think some of it has to do with the canbus communications with the battery. In later discussions, it seems these Growatt inverters work fine with the same  battery, as long as you set the settings in some way, or if there is no comms.
Now this is a field I know a little something about. Some of these managed batteries do current control. They instruct the inverter to charge or disharge by a certain amount. Quite often these batteries will send a zero when they want the inverter to stop completely (eg when the battery is completely full or completely empty), in Victron speak we call that the DCL (discharge current limit) and the CCL (charge current limit).
The DCL=0 case is mostly uncontroversial. Pylontech batteries, for example, send this before the battery is completely empty, and that way it protects itself from very deep discharges and so prolongs the life of the battery.
The more problematic case is when the battery sends CCL=0. Then the kind of toplogy of your inverter, and how your PV is coupled, comes into play.
As one example, imagine an SMA system. All your PV is tied on the AC side, using SunnyBoy grid-tie inverters. Then you have a SunnyIsland inverter connected to the battery. This inverter charges the battery and listens to the CAN-bus BMS on the battery. If the battery says CCL=0, the inverter can do that. It does not affect the delivery of PV at all. That's tied on the other side, flows normally to the loads, and out onto the grid if not limited.
Or consider a Goodwe. The PV connects directly to the high voltage DC bus, in other words even though it is a hybrid, the PV ties onto the grid in a very similar manner to the SMA example above, on the high voltage side. It can take the battery current right down to zero and just leave it there, without affecting PV delivery at all.
But now consider the cases where the PV is DC-tied, which is the case with this Growatt and also with many Victron systems. This is what you could call a "push pull" system. The DC chargers push current into the DC bus (and the batteries), and the inverter takes current from the same. If the load and the PV does not quite match, the remainder naturally comes from the battery.
Now imagine trying to do current control in a setup like this. With a hybrid inverter, some of that is possible. You can mix in some grid power in order to comply with a lower DCL, and you can limit solar chargers to comply with a lower CCL, but the basic problem remains: That in a DC-coupled setup, the battery is an integral part of the power delivery mechanism, and a complete zero situation is never going to happen.
Now I get to my point: I think these troubles start when batteries designed for one kind of ecosystem (the current-control world) is used in the other ecosystem. The battery says CCL=0, and so the inverter stops all charging (throttles the MPPTs to zero), and then the inverter has no choice but to discharge the battery rather than use the PV. After a while, the battery raises the CCL again (since it is now down to 95%) and suddenly the world returns to normal, for a while.
This gives you that little bit of micro-cycling at the top. And of course you don't want that.
The solution is to not do current control, but to adjust the charge voltage of the battery. If you don't want the battery to charge, lowering the charge voltage will stop that. It's as sure as the fact that water cannot run uphill. But that would be the "other" kind of ecosystem I referred to.
Now some inverter makers have workarounds implemented to bridge these little issues. And I assume, Growatt hasn't got there yet.

I can now comfortably give my 5cents of opinion on the 100-95% matter as I have substantially researched this topic.
Research shows that keeping the Li battery at 100% float is the WORST thing one can do to the battery. The cycling is the doing of the BMS and not the inverter. It is the way the battery is intended to be run. Not as the majority do by setting user setting so that the inverter overwrites the BMS.
Simple example of a laptop- if I set my Asus laptop to max battery life on the battery optimiser it charges to 100% then cycles between 90 and 100 while plugged in.
Batteries need to work,not stay at float. This is the normal practise.
 

Hi All. So I am still trying to make sense of this 95% 100% SOC charge micro cycling explained here. I stumbled onto this: https://marinehowto.com/lifepo4-batteries-on-boats/ as provided by another thread: 
 
 
In that article (I did not read the whole, long thing so might have missed other info...), if you search for "DURATION AT TARGET VOLTAGE (Over-Absorbing):", you will see that keeping a LFP battery at 100% SOC at the absorption stage (constant voltage) for a long time (like what is done with AGMs or GELs) is very bad and charging needs to be cut, stopped completely at this stage and voltage needs to drop lower. They should not be kept in float. As @SiliconKid mentioned, these inverters cannot power the load from solar without going through the battery (I assume the inverter does not have the ability the sync with the utility and blend power - therefore you need the battery to help the solar panels provide as stable output), therefore we are now in a state where the MPPT cannot give any more current to the battery, cannot bypass the battery, and therefore needs to shut down completely. Everything starts back up as soon as the LFP battery's voltage reduces to safe levels again. 
Anyway, so to me it seems to be ok - if I understand it correctly. I am still curious as to how other (cheap) inverters handles this situation. It looks as if they should do the same, except if they can blend utility and solar to power the load without batteries (like the 5000ES)
 

Hi Guys, I'm new to the forum and I have just done my first back up installation. Initially my intentions was to do a back up installation just for loadshedding. But now I see that it will be a waste if I don't add solar panels to the system. I have installed 1xGrowatt SPF5000TL-HVM and 2x Pylontech US2000 2.4Kwh batteries. The plan is to add a second Inverter and at least 4 solar panels for now and increase the capacity when/if needed. I'm not a qualified Electrician nor an installer, but I have a solid Electrical engineering background. I'm not a specialist and I 'm new to solar installations, so I will be coming to you guys for some advice. 
I'm currently using 4mm2 wires to supply power to the inverter and from the inverter to supply load. The stove and geyser is not wired to the inverter, only lights and plugs are currently wired. With the addition of the second inverter, I'm going to wire the geyser and stove too. My question, will the 4mm2 wires used to supply my load, be ok to power everything including the geyser and stove? Or should I get a 6mm2? Once the installation is complete, I'm going to have to get an Electrician to come and inspect the whole house wiring and issue a CoC. Can you recommend a good electrician in Johannesburg, Randburg area?

Need some help,
Seeing that my inverter is behind my fridge and that Growatt software is on a delay, is there anyway I can get some realtime data? The PV Keeper software does work but it seems limited i.t.o. logging and graphing. I do like the look of Watchpower and from there perhaps export to a graphing tool that can show some nice realtime graphs. The idea is to have a tablet of sorts up on the wall next to the fridge.
Anyone have something similar going that wouldn't mind sharing how they are doing it?

Tnx for the compliment,yes the electrician was a very nice guy that came out at last minute and didn't charge an arm and leg to redo the DB.
Will recommend him, he is in PTA East Moreletta Park..
 
Finally my wife thanked me, not only for not having load shedding this morning but also for having her kitchen back, and I am back working in my room as the inlaws are over again... Might have to rip out the floor next.
 
I measured the distance between the fridge and inverter once I moved it back in, 50cm.
Doubt that will give any heat issues, I did put quite some strain on the inverter today, at some stage trying to overload with geyser, pool, washing machine, coffee machine, dishwasher but it never switched off. It did go above 7kva for split seconds but that was it. I will definitely pay attention to the temp in the summer.
All that is left is to tidy the wiring around the combiner box and to label the DB.
I am very happy with my setup and looking forward to optimize usage.
I did measure quite a bit of voltage drop, around 16V. I am using 6mm wire from the panel to the combiner (15-20m) and 16mm from combiner to inverter (7m), little bit off heat on the fuses but the cables were cool. PV wattage peaked at around 3300W, I might be able to add another panel to each string but definitely not now.
Last night the battery discharged to 50% around 12am, then recharged using eskom and discharged again to 50% at 7 this morning then started charging by the solar around 7am
The monitoring software is still a bit of a nuisance for not being instant, but it will do. (I did receive a Monitor software on a CD, still have to check that out)
Here are some screenshots of the mobile app and cloud server.
If anyone is not yet convinced to get solar or a Growatt inverter...I am certainly glad I did it. used 15kWh from solar today and no eskom...
Cheerio, thanks for reading.
 
 
 

Tnx for the compliment,yes the electrician was a very nice guy that came out at last minute and didn't charge an arm and leg to redo the DB.
Will recommend him, he is in PTA East Moreletta Park..
 
Finally my wife thanked me, not only for not having load shedding this morning but also for having her kitchen back, and I am back working in my room as the inlaws are over again... Might have to rip out the floor next.
 
I measured the distance between the fridge and inverter once I moved it back in, 50cm.
Doubt that will give any heat issues, I did put quite some strain on the inverter today, at some stage trying to overload with geyser, pool, washing machine, coffee machine, dishwasher but it never switched off. It did go above 7kva for split seconds but that was it. I will definitely pay attention to the temp in the summer.
All that is left is to tidy the wiring around the combiner box and to label the DB.
I am very happy with my setup and looking forward to optimize usage.
I did measure quite a bit of voltage drop, around 16V. I am using 6mm wire from the panel to the combiner (15-20m) and 16mm from combiner to inverter (7m), little bit off heat on the fuses but the cables were cool. PV wattage peaked at around 3300W, I might be able to add another panel to each string but definitely not now.
Last night the battery discharged to 50% around 12am, then recharged using eskom and discharged again to 50% at 7 this morning then started charging by the solar around 7am
The monitoring software is still a bit of a nuisance for not being instant, but it will do. (I did receive a Monitor software on a CD, still have to check that out)
Here are some screenshots of the mobile app and cloud server.
If anyone is not yet convinced to get solar or a Growatt inverter...I am certainly glad I did it. used 15kWh from solar today and no eskom...
Cheerio, thanks for reading.
 
 
 

Tnx for the compliment,yes the electrician was a very nice guy that came out at last minute and didn't charge an arm and leg to redo the DB.
Will recommend him, he is in PTA East Moreletta Park..
 
Finally my wife thanked me, not only for not having load shedding this morning but also for having her kitchen back, and I am back working in my room as the inlaws are over again... Might have to rip out the floor next.
 
I measured the distance between the fridge and inverter once I moved it back in, 50cm.
Doubt that will give any heat issues, I did put quite some strain on the inverter today, at some stage trying to overload with geyser, pool, washing machine, coffee machine, dishwasher but it never switched off. It did go above 7kva for split seconds but that was it. I will definitely pay attention to the temp in the summer.
All that is left is to tidy the wiring around the combiner box and to label the DB.
I am very happy with my setup and looking forward to optimize usage.
I did measure quite a bit of voltage drop, around 16V. I am using 6mm wire from the panel to the combiner (15-20m) and 16mm from combiner to inverter (7m), little bit off heat on the fuses but the cables were cool. PV wattage peaked at around 3300W, I might be able to add another panel to each string but definitely not now.
Last night the battery discharged to 50% around 12am, then recharged using eskom and discharged again to 50% at 7 this morning then started charging by the solar around 7am
The monitoring software is still a bit of a nuisance for not being instant, but it will do. (I did receive a Monitor software on a CD, still have to check that out)
Here are some screenshots of the mobile app and cloud server.
If anyone is not yet convinced to get solar or a Growatt inverter...I am certainly glad I did it. used 15kWh from solar today and no eskom...
Cheerio, thanks for reading.
 
 
 

Tnx for the compliment,yes the electrician was a very nice guy that came out at last minute and didn't charge an arm and leg to redo the DB.
Will recommend him, he is in PTA East Moreletta Park..
 
Finally my wife thanked me, not only for not having load shedding this morning but also for having her kitchen back, and I am back working in my room as the inlaws are over again... Might have to rip out the floor next.
 
I measured the distance between the fridge and inverter once I moved it back in, 50cm.
Doubt that will give any heat issues, I did put quite some strain on the inverter today, at some stage trying to overload with geyser, pool, washing machine, coffee machine, dishwasher but it never switched off. It did go above 7kva for split seconds but that was it. I will definitely pay attention to the temp in the summer.
All that is left is to tidy the wiring around the combiner box and to label the DB.
I am very happy with my setup and looking forward to optimize usage.
I did measure quite a bit of voltage drop, around 16V. I am using 6mm wire from the panel to the combiner (15-20m) and 16mm from combiner to inverter (7m), little bit off heat on the fuses but the cables were cool. PV wattage peaked at around 3300W, I might be able to add another panel to each string but definitely not now.
Last night the battery discharged to 50% around 12am, then recharged using eskom and discharged again to 50% at 7 this morning then started charging by the solar around 7am
The monitoring software is still a bit of a nuisance for not being instant, but it will do. (I did receive a Monitor software on a CD, still have to check that out)
Here are some screenshots of the mobile app and cloud server.
If anyone is not yet convinced to get solar or a Growatt inverter...I am certainly glad I did it. used 15kWh from solar today and no eskom...
Cheerio, thanks for reading.
 
 
 

What an eventful and tiring two days. It was all worth it, especially when I flipped the switch to change over to the inverter and gone was my days of load shedding.
So yesterday the Electrician came over to rewire the DB while I did some further wiring and mounted the inverter at its secret spot behind my fridge.
About 40cm gap between the fridge and back walls. Everything will be nicely tucked away in a hole. I don't believe heat will be an issue but I will monitor it closely
When all the old circuit breakers were removed the Electrician showed me the aftermath of what appears to be damage over the years of loose connections, an accident waiting to happen.
So the old breaker box was converted to DIN rail and it looks so much better.
The changeover switch works like a dream, easy to bypass the inverter to eskom when work is needed, also with another switch  to kill the mains to the inverter.
I wanted all the switches in 1 DB, luckily I had the space.
 
The main cables to and from the inverter was pulled through the back of the DB that is conveniently located on the other side of where the cables needed to be. A short reroute through the kitchen and behind the fridge.
Also received the combiner box this morning and finished pulling those cables about 15m to the roof.
5 pairs of cables later and a brain fart left me with all the wires nicely pulled through to the combiner box but with NO idea which cable is on what panel.... back I went again, pulling back and forth to label them. To get on the roof is a mission by itself and a walk to the other side with the ladder(to short to reach the roof in 1 go)
All in all, I am happy. The inverter has some fan noise (quite loud) with any load above 600 ish Watt, but believe this will be more quite once the fridge goes back in.
Tomorrow I will do the finishing touches and tidy up with some trunking and try and find a way to do live monitoring using the wifi dongle. Currently it appears to be delayed by a few minutes as it connects to a cloud server for the logging.
On a side note, there was no need to flash the firmware to make the BMS work as intended.
I only changed the dip switches on the battery and connected the monitor cable in the right ports.