This forum has been pretty helpful during my research and setup so wanted to start by saying thanks!
I have this newly installed at my cabin and it went pretty simple I guess except for some reason the power fluctuates seriously and almost with a rhythm. I thought it was clouds yesterday but today we have full sun, no clouds. Any reason why this might be happening?
I have 8, 100 watt panels, two rows of 4 (series) connected in parallel. All of a sudden voltage drops to the low 20's and then, zoom it bumps back up to normal.
I recorded it:
https://www.youtube.com/watch?v=PDMWyIqlZwM
I never had this issue with my old controller. I am assuming this is a setting somewhere?
What kind of batteries and what are your setpoints ?
Could be a wiring issue too - like a loose connection ?
Was it just the controller that you replaced or did you also rewire other things ?
Larry
I just looked at your video again.
Did you use the Midnite String Calculator to see what that says for your setup.
I would double check the PV wiring and make sure that is all right .
Isolate PV from the Classic and take some voltage readings.
Larry
deep in the settings for the classic, are 3 types of solar tracking algorithms, consider changing those if nothing else works.
Also, have you let the classic use it's default settings, or are they tweaked ?
Are you pressing the ENTER button to turn the BACKLIGHT ON after it goes out in power save mode?
Wow, so many responses!! Sorry, was off-gridding a bit and didn't get back here to answer.
I did recheck all the wiring (which I did recently upgrade much of it as I downgraded to 12v from 24v). All my connections are solid.
My batteries are two of these connected in parallel: https://amzn.to/3xylRWP
I also cleaned the panels thinking it could be a dust issue? No change.
There is zero shade on the panels on the day I posted this, not a cloud in the sky.
I did change the algorithm to "Dynamic" which seems to have solved this issue.
https://www.midnitesolar.com/pdfs/classic_manual_Rev_1933.pdf
"Dynamic
This is typically used for PV (solar) input sources and tries to follow, on a slow dynamic basis, the changing conditions of the input source. This mode has one user adjustment which is a forced sweep perturb trigger interval for times when the input condition changes do not trigger a dynamic sweep. The interval is in units of minutes."
Now all seems to be working perfectly?
Hi Jafo. Looks to me that the Classic is just sweeping down as close as it can to the battery to make sure there is not any max power point peaks down there. That is why it is going so low. Looked to me like it was in Legacy P&O (Perturb and Observe) which always works well but as you saw, can be very slow at lower voltages.
The reason it goes so low is only because of partial shading. Partial shading of the PV array is what can cause those lower MPP points and even multiple maximum power point voltages of the PV.
Obviously, you don't want to use that tracking mode. I can't even remember exactly how Dynamic tracking worked ? Is this an older Classic ?
Have you tried "SOLAR" tracking mode ? This is the fastest mode for tracking and may work best especially as you have a high Voc as shown by the high Vmp voltage that the Classic returns to like in your video. Thank you BTW for taking that video ! Very useful here.
There is also a mode in the Classic for Hydro. Hydro is more like P&O BUT I think it has a limit that you can set for how low the Classic brings the PV voltage down. So, instead of it taking all that extra time going low to near the battery voltage, it can stop at a higher voltage.
See if that feature is in your software in that Classic and try that if possible and if SOLAR mode doesn't fix this issue.
boB
I used the solar mode by default right out of the box, then tried legacy P&O but they both worked the same, only the dynamic one fixed this. Not sure how shading could affect this since there was no shade at the time. Crystal clear day and I have no trees or other obstacles to shade the panels with. I even washed the panels to make sure it wasn't dust.
It is very odd because I never had this issue with other controllers. I am glad to see that it seems odd to everyone else too lol..
I just bought the controller new on Amazon (Classic 150).
This is great feedback, thanks so much for it!
Hi Jafo..,
I, too, had wondered the version of Classic Firmware. Some of the previous FW versions had a few issues with Sweeping to find the MPP voltag.
Press the left round button, about six times from the Main Status screen on the Classic, and please tell us, what is the Classic FW version.
Thanks, Vic
The SOLAR mode should NOT be acting nearly as slowly as the mode shown in your video.
Could you change to SOLAR mode and video that ?
That might help to see what is going on as well.
boB
I have the same problem
I also just switched to dynamic "on" and
seems to have stabilized.