Help with my current setup. Growatt 3000TL LVM-48p

[Creggh]

Hello. First-Timer here. I have a Growatt 3000TL LVM-48P with 6 -250 total of 1500 watts. PV panels are wired in series. I have 16 Data Safe AGM batteries wired in series and parallel. At 48v I have roughly 380 amp hours worth of batteries (see attached pics). I have an Igen 4500 westinghouse generator wired in.

When I originally purchased the Growatt from Signature solar in 2021, the tech told me to wire all the 6 panels in series and then connected them into the growatt. I run about 200 watts 24 hours a day. Just a Star Link 24-7, a few lights, and a Cpap machine at night. 6 solar panels facing south. When I get up in the morning I'm down to about 47 volts or less. At the end of a summer day I might be charged up to 49 volts. It is a constant battle. I run the generator for a few hours at night, and that doesn't seem to charge it too much, maybe to 50 Volts.

So I bought 4- 370 watt panels last week. I then contacted Signature solar and spoke to a tech. First thing he said was I can't run both sets of panels because they are different watts and voltages? Okay I get that. So I gave him my setup and he said I should not be running the 6-250 watt panels in series? Even though that is what I was told to do by the other Tech. He then calculated which panels were better for my system, either the 6-250 watt panels or the 4-370 watt panels. He advised I should run the 6-250 watt panels. 3 in a series and 3 in a series and use a combiner and then plug it in? He advised I could have damaged the Growatt by running too much voltage through it. He said the Maximum PV array open circuit voltage is 145 vdc?

So now I'm even more confused. I'm a DIY guy and can put anything together but I don't really understand the numbers. I wanted to add panels so my batteries would charge quicker. And after speaking to the tech people I'm not feeling confident I'm getting the right answers

First, is 2 strings of 3 into a combiner plug the correct way?
Second, How can I add panels?

Any help is greatly appreciated.

 

[sunshine_eggo]

Hello. First-Timer here. I have a Growatt 3000TL LVM-48P with 6 -250 total of 1500 watts. PV panels are wired in series. I have 16 Data Safe AGM batteries wired in series and parallel. At 48v I have roughly 380 amp hours worth of batteries (see attached pics). I have an Igen 4500 westinghouse generator wired in.

When I originally purchased the Growatt from Signature solar in 2021, the tech told me to wire all the 6 panels in series and then connected them into the growatt. I run about 200 watts 24 hours a day. Just a Star Link 24-7, a few lights, and a Cpap machine at night. 6 solar panels facing south. When I get up in the morning I'm down to about 47 volts or less. At the end of a summer day I might be charged up to 49 volts. It is a constant battle. I run the generator for a few hours at night, and that doesn't seem to charge it too much, maybe to 50 Volts.

You're destroying your batteries. It's a wonder they've lasted this long. You need to be reaching 57.6V near daily. You also need to confirm all the 12V are at the same voltage within 0.05V.

So I bought 4- 370 watt panels last week. I then contacted Signature solar and spoke to a tech. First thing he said was I can't run both sets of panels because they are different watts and voltages? Okay I get that. So I gave him my setup and he said I should not be running the 6-250 watt panels in series?

Agree. You're lucky the MPPT hasn't melted down, sparked, let the blue smoke out, etc.

6*38Voc = 228V. your MPPT is limited to 145V per the link you've provided.

Either you've linked the wrong MPPT, you actually aren't in 6S, or you have the most amazingly over-voltage tolerant MPPT ever made.

This may also explain why 1500W of PV can't meet a mere 4.8kWh of daily needs. Should be pretty easy unless you have really bad weather.

what is your typical noon-time, full sun PV power?

Even though that is what I was told to do by the other Tech.

You didn't talk to a tech. You talked to a new hire that hadn't been trained, you're remembering it wrong, or that tech assumed this unit had a 250Voc limit, which many do.

He then calculated which panels were better for my system, either the 6-250 watt panels or the 4-370 watt panels. He advised I should run the 6-250 watt panels. 3 in a series and 3 in a series and use a combiner and then plug it in? He advised I could have damaged the Growatt by running too much voltage through it. He said the Maximum PV array open circuit voltage is 145 vdc?

This tech is giving you the correct information based on the specs you have provided.

So now I'm even more confused. I'm a DIY guy and can put anything together but I don't really understand the numbers. I wanted to add panels so my batteries would charge quicker. And after speaking to the tech people I'm not feeling confident I'm getting the right answers

You are talking to the right tech now.

First, is 2 strings of 3 into a combiner plug the correct way?

It's a way.

You could quickly put them in parallel with MC4 parallel connectors like these:

https://www.amazon.com/BougeRV-Connectors-Connector-Parallel-Connection/dp/B07DJ5PHSB

Rewire into 2 3S strings, then parallel them with these connectors.

Second, How can I add panels?

Combiner box or additional MC4 connectors. If you exceed 30A PV current you can't use MC4 parallel connectors. If you go more than two strings in parallel, you'll need to fuse each string.

You can put additional panels in parallel provided their string Vmp value is within about 5-10%, i.e., you'd want to add panels with a Vmp of about 28-35V.

Assuming you haven't damaged the MPPT, rewiring your array correctly may make it come alive and produce more power than it ever has, and you don't need to add more. If it's been damaged, it will need to be repaired or replaced.

 

[Creggh]

57V daily upon a full charge? Okay, I will use a multimeter and check the voltage on each battery independently and make sure they are within .05

Not sure about Noon time power. I will check this weekend when I go back up to the cabin.

I already purchased that same combine from amazon and will be here tomorrow. I hope you are correct about that. And thanks for your help and patience. Hopefully I haven't fried everything.

 

[sunshine_eggo]

57V daily upon a full charge? Okay, I will use a multimeter and check the voltage on each battery independently and make sure they are within .05

Based on 4X 12V in series for 48V, you want to charge to about 14.4V per battery. This isn't an absolute, but it's an acceptable number for most lead-acid batteries. Gels tend to peak at 14.0V/56.0V and some AGM like it higher at 14.8/59.2.

Not sure about Noon time power. I will check this weekend when I go back up to the cabin.

That would give a good idea as to how the array performs in its current state.

I already purchased that same combine from amazon and will be here tomorrow. I hope you are correct about that. And thanks for your help and patience. Hopefully I haven't fried everything.

Good luck!