MPPT and series solar panels don’t output full voltage/current until 10:30AM?!?

[cottersay]

I hope someone has an answer for this. My 4x 100W Renogy solar panels in series and my new MPPT solar controller (EPEVER 40A/150V) will take two hours in the morning to output any meaningful voltage and current. For instance, at 9AM with *full* Sun exposure here in Arizona, the MT50 digital display shows the four series panels as producing only 13V and 3.6A, while the Lithium batteries (BattleBorn) are receiving an equally low input. After an hour or two, the total power will slowly increase, with the voltage and current rising to the expected 80V input and 26A output.

Any ideas, ‘cause I hate losing two precious hours of charging-time each and every day!!

Thank you!

 

[Solar Guppy]

Likely you have shading on some of the panels, take a picture at 9AM of all the panels.

If not the above, the mppt tracking appears to sub-par working in low wattage modes, with only 400 watts STC and early in the morning may only have 20-40 watts available to harvest or the tracking is stuck due to the multi-hump power points. It can be tricky for the firmware to work in that power range.

 

[TomC4306]

What is your latitude? What is the tilt from horizontal of the panels? Are they facing 180° South?

 

[TomC4306]

This is one of the reasons I split my array in half with half pointing at 155° and the other half pointing at 205°. I sacrifice a bit of peak power but broaden production through the day particularly morning

 

[cottersay]

Hi guys,

Thanks for the responses! To answer the questions: There is no shading of any of the panels at any time. I also adjust the panels throughout the day so as to point directly towards the sun, both in azimuth and elevation. I am at a Latitude of 34.048927 (Arizona). No clouds in the sky. (My separate 100W single panel with PWM controller outputs about the same power in the morning as the 4x MPPT setup!)

Confusing, but I too had wondered if it is some uber-slow MPPT tracking issue, but I don't want to send the controller back if it is simply some operator error issue!

Any MT50 control head setup parameters that I can change to mitigate this problem?

PS: It gets down to 35 degrees here in AZ during the night; possible that the BattleBorn BMS is limiting charging until the batts heat up?

 

[TomC4306]

Hi guys,

Thanks for the responses! To answer the questions: There is no shading of any of the panels at any time. I also adjust the panels throughout the day so as to point directly towards the sun, both in azimuth and elevation. I am at a Latitude of 34.048927 (Arizona). No clouds in the sky. (My separate 100W single panel with PWM controller outputs about the same power in the morning as the 4x MPPT setup!)

Confusing, but I too had wondered if it is some uber-slow MPPT tracking issue, but I don't want to send the controller back if it is simply some operator error issue!

Any MT50 control head setup parameters that I can change to mitigate this problem?

PS: It gets down to 35 degrees here in AZ during the night; possible that the BattleBorn BMS is limiting charging until the batts heat up?

Possible on the temp. I don't know what battleborn sets their BMS at. I think my next step would be verify each panel individually with the pwm

 

[Solar Guppy]

Its the mppt tracking then, its designed for much larger systems. I'm pretty sure I know why, but I would be going into the weeds explaining how low cost controllers do not have the resolution to track at low power levels and can get stuck.

For a quick fix if you are just using the 4 panels, is put them all parallel. Likely it will track just fine like that.

 

[cottersay]

Its the mppt tracking then, its designed for much larger systems. I'm pretty sure I know why, but I would be going into the weeds explaining how low cost controllers do not have the resolution to track at low power levels and can get stuck.

For a quick fix if you are just using the 4 panels, is put them all parallel. Likely it will track just fine like that.

Thanks Guppy, but they are in series.

 

[Solar Guppy]

Thanks Guppy, but they are in series.

Parallel

 

[Mattb4]

If your wiring allows you to, try changing configuration to 2S2P or the 4P that SG is suggesting. I do not know about the Epever but my Make Sky Blue SCC suggests keeping panel voltage about 1.5 to 2 times the battery voltage for best results.

 

[MisterSandals]

the MT50 digital display shows the four series panels as producing only 13V and 3.6A,

Have you measured the volts and amps of the array without being connected to anything? Your numbers sound unusually low for full, direct sun.

 

[Solar Guppy]

Have you measured the volts and amps of the array without being connected to anything? Your numbers sound unusually low for full, direct sun.

That's the controller sweeping down to minimum voltage but maximum current Isc of the array at 9:00 am ( about 45 watts )

Few lines later in the post was written its 80V input with 26 amps battery side ( about 350 watts ) later in the day with manual tracking, so all 4 panels are working just fine.

Likely that controller does a sweep and stays there until some power level triggers a new sweep, just a sub par mppt algorithm

 

[MisterSandals]

Few lines later in the post was written its 80V input with 26 amps battery side ( about 350 watts ) later in the day with manual tracking, so all 4 panels are working just fine.

Okay, it sounds like you're not interested in measuring your array. I just cannot see how 1000W of solar, in full direct sun producing 350W is "working just fine".

I would suspect the array long before proclaiming that the MPPT algorithm is sub par. Partly because i could measure the array and would have to guess about the MPPT algorithm.

It could even be an intermittent or poor MC4 connection somewhere in your array. It only takes a few minutes to experiment with 2 different 2S setups which would greatly narrow down any array issues.

 

[Solar Guppy]

Okay, it sounds like you're not interested in measuring your array. I just cannot see how 1000W of solar, in full direct sun producing 350W is "working just fine".

I would suspect the array long before proclaiming that the MPPT algorithm is sub par. Partly because i could measure the array and would have to guess about the MPPT algorithm.

It could even be an intermittent or poor MC4 connection somewhere in your array. It only takes a few minutes to experiment with 2 different 2S setups which would greatly narrow down any array issues.

I'm not the OP, it is not my array, the OP wrote there are 4 100W panels in series.

I'm an SME in mppt, Xantrex is my work, Morningstar I was part of the TriStar mppt efforts, so I butt in when this topic comes up to help others.

 

[MisterSandals]

I'm not the OP, it is not my array, the OP wrote there are 4 100W panels in series.

Thanks, i got some things cross wired in my head! (not the first time! appreciate the help!)

 

[cottersay]

SOLVED! Thanks guys for all your help, and especially to MisterSandals! I got up early (for low temperatures), opened up all the connections and took the OCV of all panels. They tested perfectly. I then put them back in series and tested the OCV of the entire string. Perfect. I then connected the series string back to the MPPT controller. The controller now saw the entire proper voltage of 77V from the panels and 23A into the Lithiums!
It seems that one of the MC4s was not a good connection in the cold of the morning, and that the heat of the day expanded the MC4 for a decent connection!! (Weird that such an issue produced any voltage/current output in the AM).

 

[cottersay]

Just as a quick addendum for anyone interested: After 10 or 20 minutes or so of cloudy sun, then with the bright sun coming back fully out of the clouds, I found that this MPPT solar controller will go back into its original problem (the MPPT's display showing only 13V input and 3.6A output). This seems to happen every time. However -- and this is the weird and interesting part -- when I disconnect the panels from the controller for a split second, and then immediately connect them back to the MPPT, the MPPT shows its full power of 80V input and 26A output!
Really odd, but I'm starting to think that this is unsolvable, and maybe I need to replace the damn solar controller again (this will be my fourth one that's given up the ghost!!)