[Fixed] 12kPV MPPT extremely low power from one array

[thomaspu]

I recently added a second solar array to my EG4 12kPV inverter. Unfortunately, I think I have discovered an issue with the 12kPV's MPPT. Hopefully you all can point out something that I have done wrong. I originally only had the 10 panels of array 1 up on my roof. All was well, the panels would peak around 2,800watts during the day. Once I added array 2, array 1 (PV1) only produces about 50-400watts. This is with all panels in full sun. For instance:
My Tigo optimizers confirm that the PV1 array is producing little power:

This is with all panels in FULL sun:

Array 1 is a 10-panel array (two parallel connected series strings of 5 panels each). These panels are Rich Solar Mega400 (400-watt) panels. Vmp=41.2v, Imp=9.71a. This should run at 206v (248 Voc max).

Array 2 is a 16-panel array (two parallel connected series strings of 8 panels each). These panels are Aionrise (395-watt) panels. Vmp=39.3v, Imp=10.0a. These should run at 314.4v (385 Voc max).

At first I thought that I somehow wired something wrong or maybe had a loose connection. After an hour on the roof verifying wiring connections. I couldn't find anything wrong. During installation, I was able to verify that the voltages of each string were what I expected.

I decided to back out my changes. I disconnected array 2 (PV2) at the inverter (I initiated rapid shutdown, waited a little and then initiated my DC disconnect for the panels). After doing so, and turning everything back on, the inverter reports that array 1 (PV1) is operating like I would expect and is soon producing 2,200+ watts of power. Nothing wrong there.

If I reconnect array 2 (PV2) and disconnect array 1 (PV1), array 2 begins producing power like I'd expect. 3,500+ watts. Nothing wrong there either.

Reconnecting so that both arrays are connected, array 1 (PV1)'s power production tanks. Seems to be an issue with the MPPT on the inverter. Once both are connected, PV1 is operating very poorly.

The inverter specs should be able to handle these two arrays just fine. Voltages (Voc max) and current (Isc max) of each array are within the operating ranges. It claims it has 2 MPPTs, these *should* be operating independently of one another. At this point, I think the EG4 inverter is to blame.

Any help is appreciated. I also emailed signature solar (who I purchased the inverter from). Does anyone have any experience with this model of inverter running two different arrays (each on their own MPPT)?

 

[Suijkerbuijk]

Only thing you can do is this .
Switch to solarpanels cables from the input.
Pv1 become pv2
Pv2 become pv1

See if the same problem stay .
Yes than somting with the inverter .
Switch the problem than its somting wrong with the solarpanels.

By wy are boths pv1 and pv2 difrence volts ?

 

[DIYrich]

Connect both arrays, and turn on a really large load. It might be self limiting for some reason.

 

[JBoffgrid2022]

From the manual:
The inverter has two separate MPPTs which will utilize up to 25A each. Therefore, two strings can be paralleled for any modules having less than 12.5A (Imp) rating. When sizing strings for each MPPT, they MUST be the same model, brand and number per string (series and parallel). All panels in a series/parallel string should face the same orientation and be exposed to roughly the same shading across the string. Consideration should be placed on string location and wiring order on the racking to minimize shading effects. One shaded module can disproportionately reduce output for the entire string. This is because shading on a solar module will cause a drop in voltage. All panels in a string will drop to match the lowest voltage experienced in any module. Using Optimizers and/or avoiding linear strings in favor of rectangular strings can minimize losses due to shading.


Could your issue lie in the low current coming from "Array #1"? Each array can utilize up to 25A each, but you're only supplying 9A to Array #1. Could you hook up all your panels on Array #1 in series (10 x 41.2V = 412V)? This would be far below the 600V hard limit of max volts. Unless I misunderstood your explanation? Could you repost with better description of your panel configuration and how they hook up to your inverter?

 

[DIYrich]

Could your issue lie in the low current coming from "Array #1"? Each array can utilize up to 25A each, but you're only supplying 9A to Array #1. Unless I misunderstood your explanation? Could you repost with better description of your panel configuration and how they hook up to your inverter

Looks like a&b are 5s2p into mppt1, and c&d are 8s2p into mppt2.

 

[JBoffgrid2022]

Connect both arrays, and turn on a really large load. It might be self limiting for some reason.

If the SOC is low on the batteries, wouldn't they still provide max power from the arrays?

 

[thomaspu]

When I was up on the roof, I had one of those clamps style meters for reading current on array 1 and I would see the current reading jump up quickly from 0.5 or so to 2 to 3.5 amp and then quickly drop back down and repeat the process.

Sure seems like an MPPT issue. The two arrays are about 100v difference, but each array is on its own MPPT

 

[JBoffgrid2022]

When I was up on the roof, I had one of those clamps style meters for reading current on array 1 and I would see the current reading jump up quickly from 0.5 or so to 2 to 3.5 amp and then quickly drop back down and repeat the process.

Sure seems like an MPPT issue. The two arrays are about 100v difference, but each array is on its own MPPT

Could you share some screen shots of the "data" graphs on your EG4 monitor app that could show this? If the inverter recorded this fluctuation you'd see it on the graph.

 

[Quattrohead]

Swap the arrays on the mppts and see who does what then.
There are settings for PV startup voltage and to select whether it uses pv1, pv2 or both and this setting sounds well worth investigating for your situation.

 

[thomaspu]

Could you share some screen shots of the "data" graphs on your EG4 monitor app that could show this? If the inverter recorded this fluctuation you'd see it on the graph.

Looks like it caught it. Seems to be "flapping". The big peak is when I had array 2 (PV2) physically unplugged.

 

[thomaspu]

My "Start PV Voltage" was a little high, 200v. Changed it to 160v. We'll see what happens later today when the sun comes up.

 

[JBoffgrid2022]

Have you tried swapping the PV inputs on the inverter to see if the same problem populates? This may be a simple fix or inverter hardware issue, IDK.
If you haven't already, reach out to the EG4 tech team. US customer service number is: (903) 441-2090. A few of their reps are on this forum as well. @EG4TechSolutionsTeam @EG4 Electronics James

 

[JBoffgrid2022]

My "Start PV Voltage" was a little high, 200v. Changed it to 160v. We'll see what happens later today when the sun comes up.

View attachment 248617

I would check with EG4 before you start meddling with those settings. Better safer than sorry!

 

[Quattrohead]

My "Start PV Voltage" was a little high, 200v. Changed it to 160v. We'll see what happens later today when the sun comes up.

That was too high. Mine are at 140v on an 18k.

 

[thomaspu]

I'm hoping that is the setting I needed to change. Looking at the status, both strings are well below 200v currently:

I could see where if the MPPT was regulating the voltage lower than the startup voltage that it would then stop, and then the panels voltage would likely jump up to the open short voltage which would be well above the threshold and then the MPPT would kick in and drop the voltage, thus the floppin'

I'm still waiting though. The PV1 wattage is really low still, but then there is a chimney that shades it for part of the morning and part of the neighbors tree might also be shading. Here's hoping!

 

[thomaspu]

I'm marking this as fixed! Thanks to all for thoughts and input!

 

[SignatureSolarJess]

Hey! Do you have a ticket open for this?

 

[thomaspu]

Hey! Do you have a ticket open for this?

Not that I know of. I had emailed signature solar support Sunday, and then had replied to that email to let them know I had fixed the problem. I doubt they had time to open a ticket!

 

[SignatureSolarJess]

Not that I know of. I had emailed signature solar support Sunday, and then had replied to that email to let them know I had fixed the problem. I doubt they had time to open a ticket!

Awesome! I'll be sure to find that form submission and close it out Please don't hesitate to reach out again if needed!

 

[JBoffgrid2022]

I'm marking this as fixed! Thanks to all for thoughts and input!

View attachment 248639

Well there ya go, that was easy!