I'm confused... the PV watts won't go above 1.3k, SPF 12000T DVM with 3 x 48v 100 AH Lifepower 4 batteries, 18 x 320 Renogy panels

[Bobby Cannon]

I have 18 x 320 Renogy Panels (320D). They are in 6 strings of 3 panels. 40v each so the string voltage is ~110v. All strings go into a 6 string combiner. This is a total of 320 x 18 = 5760 watts total. From the combiner I use 8 awg wire to the PV1 input on the Growatt SPF 12000T DVM. Note: the DVM cannot exceed 150v dc for PV.

The 3 x EG4 batteries are in parallel and connect to the Growatt. I have the Growatt programmed (option 5) for LI. This means the inverter will talk to the battery to determine when to bulk, when to float, when to switch back to grid, etc.

Now here is the problem. I cannot seem to get the inverter to pull more than 1.3kw from solar. How or when does the Growatt determine what to pull from the solar panels? It's been uber sunny the last couple days. However my load (at times) takes 80-90% of the 1.3kw so the batteries are left with a measly 200-300 watts to charge. This means I end the day with the 3 batteries only at 65-70%. I feel like there was more overhead that was available but the inverter won't pull it?

I'll take anything, comment / ideas / anything...

 

[Bobby Cannon]

Here is what today looked like. It was a great sunny day so I'm not sure why solar won't cross 1.3k...



Best state of charge I got to today was 69% which is not enough to make it the night. I know Grid will kick in and charge my batteries tonight.

 

[Bobby Cannon]

I just had a thought. Is the inverter charging at ~25 amps but at the same time the unit is running on battery which means the inverter is putting in 25amp of charge but using 20amps at the same time?

This means the inverter is talking to the batteries. The battery(s) are suggesting a certain charge rate and the inverter is just like sure that is all you need. But it's not smart enough to ramp up / down the PV rate to help with charging while using power?


Here is an example of a really bad day. Battery charge never got past 50%

 

[Bobert]

What is the voltage of your entire array when it is in the sun unplugged.

 

[Bobby Cannon]

What is the voltage of your entire array when it is in the sun unplugged.

The panels datasheet says the open circuit voltage should be 40.1v.

On my strings I'm getting around 109 to 111 v DC disconnected and the sun is blazing. When all are connected in parallel but still disconnected from the inverter it's the roughly the same 109 - 111 v DC.

 

[Bobert]

The panels datasheet says the open circuit voltage should be 40.1v.

On my strings I'm getting around 109 to 111 v DC disconnected and the sun is blazing. When all are connected in parallel but still disconnected from the inverter it's the roughly the same 109 - 111 v DC.

Have you tried using a clamp meter to verify that each string is outputting the same amperage. What is the voltage on your array when it is charging your batteries?

 

[BenQ]

If for some odd reason you don’t have a clamp meter, Drain the battery below 50% disconnect all loads, plug in one string of panels into the combiner box in the middle of the day and see what you get, add more strings to see the increase in solar production. If adding the second string does not increase production then either there is a loose connection or the combiner box is bad.

 

[Bud Martin]

If you do not have clamp-on DC Ampmeter to check each string, since you have combiner box for the six strings of your panel, the combiner box should have a fuse folder/disconnector for each string, you can try having one string connected one at a time and compare the reading of each string to see what you get.

 

[Bobby Cannon]

If you do not have clamp-on DC Ampmeter to check each string, since you have combiner box for the six strings of your panel, the combiner box should have a fuse folder/disconnector for each string, you can try having one string connected one at a time and compare the reading of each string to see what you get.

I don't a DC amp meter, but I did disconnect the main break, then disconnected all strings by opening all fuse holders in the combiner. I then close each fuse enabling the string, tested the voltage, then opened it back up. All strings seem to have a good connection.

 

[Bobby Cannon]

If for some odd reason you don’t have a clamp meter, Drain the battery below 50% disconnect all loads, plug in one string of panels into the combiner box in the middle of the day and see what you get, add more strings to see the increase in solar production. If adding the second string does not increase production then either there is a loose connection or the combiner box is bad.

I think I'll try this today.

 

[-g-g-g-]

I can strongly recommend the UNI-T UT210E AC/DC 100A clamp meter. True RMS, A, V, Cap, diode, continuity & NCV.
Pocket sized and big enough for 15mm dia cables.
I paid around £22 a few years back but it's the handiest meter I own and a diagnostic dream. Saves time and solves problems.

 

[Bobert]

I think I'll try this today.

Check the voltage at the PV inputs while charging. I have had trouble with an MPPT controller sticking at low voltage and reducing the output of the array to about 1/4 of it’s capacity in good sun.

 

[Bobby Cannon]

Check the voltage at the PV inputs while charging. I have had trouble with an MPPT controller sticking at low voltage and reducing the output of the array to about 1/4 of it’s capacity in good sun.

I just measure the voltage while it's "peaking" and it's ~106v DC with an expected Open Circuit of 120.3 v dc (perfect scenario). I'll go validate all the string individually at dinner break.

 

[Bobby Cannon]

I can strongly recommend the UNI-T UT210E AC/DC 100A clamp meter. True RMS, A, V, Cap, diode, continuity & NCV.
Pocket sized and big enough for 15mm dia cables.
I paid around £22 a few years back but it's the handiest meter I own and a diagnostic dream. Saves time and solves problems.

Ordered, thanks for the suggestion. I've been meaning to get a DC clamp meter. I have many meters but none of them can clamp read DC amps... Now I'll have one and yes it will make it much easier to troubleshoot my strings and individual panels.

 

[Bobert]

Ordered, thanks for the suggestion. I've been meaning to get a DC clamp meter. I have many meters but none of them can clamp read DC amps... Now I'll have one and yes it will make it much easier to troubleshoot my strings and individual panels.

Dc clamp meters are awesome.

 

[Bud Martin]

I don't a DC amp meter, but I did disconnect the main break, then disconnected all strings by opening all fuse holders in the combiner. I then close each fuse enabling the string, tested the voltage, then opened it back up. All strings seem to have a good connection.

So when you have only one string in place at a time, do each string produce the same power?

 

[acdoctor]

Do you have the growatt max charge set too low?

 

[Bobby Cannon]

Do you have the growatt max charge set too low?

When using LI mode, which means the Growatt Inverter is talking (or rather listening) to the EG4 batteries, this setting cannot be changed. It's controlled by the unit.


When charging at a limited 25A (1.3kw) from solar, this value reads 50A.

 

[Bobby Cannon]

I feel this has to be an inverter (all-in-one) issue because I top out at the 1.3kw on cloudy or sunny days. It's like there is something about the configuration not letting the unit go all out. I plan on putting my AC back on the unit once I get my 4th battery in on Monday.

 

[Bobby Cannon]

So when you have only one string in place at a time, do each string produce the same power?

This is the first thing I'm checking... when it's sunny again. I want the array to be peaking when I do this test. Today is cloudy so I may have to wait until tomorrow.