We have a 5KVA inverter system with 2 lithium ion US3000 pylontech batteries as the slave batteries to a further master battery which is a US5000 pylontech battery. We have 9 330watt panels. Since we installed the new master battery we are having lots of challenges getting those batteries to full capacity i am not home often but lots of the timr the battery voltages won’t have gone up much the whole day. Bare in mine we get about 4 hours of good sunlight a day and about maybe another 4 hours of mediocre sunlight. There are two possibilities for me why the batteries don’t seem to be pulling in the power necessary to be full. 
1. our panels simply are not powerfull enough to handle the extra 4.5KWH of power added to our circuit.

2 there is a configuration error of some kind with the new US5000 battery being put in the circuit. Would anyone here have suggestions? 

Hi @Ninoevans

we'll need some more details to be able to help you. Could you please post some charts of your system from a typical day - e.g. load and PV production, battery power and SOC.

Then we can better see what is going on with your system.

Let me see what i can muster up

power forum doc pdf.pdfpower forum doc.xlsx

Hi, here are some docs i have made up. This is not 100% accurate but i think relatively accurate. However, upon doing this it does seem that i see the problem. It is our generation from our panels

 

Thanks @Ninoevans

I am not sure if the data is an hourly snapshot (Watts generated and used) or cumulative Watt-hours (Wh) for each hour.

But as an estimate it suffices. Based on your data, it appears that you have generated a PV surplus of approx. 5kWh during that day. Not knowing your batteries SOC makes it difficult to tell how far the batteries were discharged/charged, but based on your approx. 7kWh deficit from your chart (and not knowing how much grid was used for that), it would make sense that your PV is not able to fully charge your batteries.

If you are discharging your 2x US3000 down to 20% (recommended for the older A/B models), then your surplus PV would not even be sufficient to charge them back to full. With the added US5000 that charging gap becomes even bigger...

The other thing that I noticed from your charts is that your peak PV production is around 1.6kW - which from your total 3kW of panels appears low (depending where in the world you are based and which season it is for you). Which inverter are you running and how are your panels wired (e.g., all 9 on a single string in series)?

Hi yes, this data is basically from what i have seen from observations of the inverter and charging cycles. I am not sure how to get the data from the inverter to show usage. Maybe if you would like better insight you can guide me on how to do that? We are running a 5 kva mercer inverter. Purchased in 2019 

model number: SOL-I-AX-5P64

13 minutes ago, Ninoevans said:

5 kva mercer inverter. model number: SOL-I-AX-5P64

I am not an expert with those inverters. Am tagging @Coulomb to maybe chime in with his endless knowledge

It seems that your inverter has 145V max VOC on the MPPT, so we would need to know how your panels are wired (e.g., 3 in series and that 3 times in parallel - 3S3P)

A quick search here in the forum produced this thread, which might be of interest for you

Where are you located?

Im located in zimbabwe, okay thank you ill look at the thread. Im not sure how they are wires either. I would have to check. I assume its 3 sets of 3 in series wired in parallel 

Thanks

I'll leave it to others with better knowledge of your inverter to advise

Edited January 5, 20251 yr by wolfandy

Hi @Ninoevans on the side of your inverter there should be a sticker (data plate) can you share a photo of that sticker and advise send me a PM of where you are in Zim.

1 hour ago, wolfandy said:

I am not an expert with those inverters. Am tagging @Coulomb to maybe chime in with his endless knowledge

It seems that your inverter has 145V max VOC on the MPPT, so we would need to know how your panels are wired (e.g., 3 in series and that 3 times in parallel - 3S3P)

A quick search here in the forum produced this thread, which might be of interest for you

Where are you located?

@wolfandy you're right the max VoC is 145DC as per the sticker sent.

Hi everyone. I have chatted to some people. We will be getting someone to come and look at the system with a panel upgrade and look at the configuration and what not. Thanks everyone for the help

7 hours ago, Moffat said:

the max VoC is 145DC as per the sticker sent.

99.9% of recent installations would be for high PV voltage. My guess is that the installer assumed the usual 90-450 V MPPT range, which isn't going to work with this inverter.

Quite possibly the solar charger has been damaged if this is the case.

I'm a little surprised that this inverter was made as recently as mid 2019.

Hi guys, so after getting some insight from a solar guy in my area he said that my battery configuration is the problem. However, i did research before buying the new battery and everyone was saying it was okay to do this as long as the newer bigger battery was the master battery. The setup is 1 - US5000 as the master battery and 2 - US3000 as the slave batteries. 

12 hours ago, Ninoevans said:

Hi guys, so after getting some insight from a solar guy in my area he said that my battery configuration is the problem. However, i did research before buying the new battery and everyone was saying it was okay to do this as long as the newer bigger battery was the master battery. The setup is 1 - US5000 as the master battery and 2 - US3000 as the slave batteries. 

Just saying your battery configuration is the problem doesn’t help sadly. Did the “solar guy” use any test meter to measure voltage or suggest a better configuration or he’s fishing for a job now?

My take is your Panels don’t seem to be enough for your setup but unfortunately limitations on your inverter max VoC (145)may limit how many more panels you can add meaning you may have to get a different inverter which allows you to put more panels. 
Is grid, when available, able to fully charge your battery bank at least to 100% full?

It would be good in the interim to also measure how much Pv your panels are outputting (with a test meter) and to know what configuration they are in. 

Thanks for that, yeah we need to look and see what voltage we get and the brightest time of day, just with the rains its not easy. Need to see what voltage they are giving out. If we do that we can see. Would swapping all the panels for a different more efficient type also work? So we can keep in that voltage range and give more power output?