RFR #1 - What gives?

[miahallen]

The troubleshooting guide in the user manual describes my problem perfectly:

Symptom:
Classic switches between Resting and Bulk MPPT repeatedly but produces 0 watts.

Solution:
Watch the IN voltage and see if it slowly drops to battery voltage (Or Close) when the Classic goes to Bulk MPPT if so this is usually a sign of a High resistance connection (Loose Connection between the Classic and DC source)


The problem is that my wiring is secure, and I even ran a 2nd connection through the front door of the house temporarily with the same results. I have 2 Classic 200 CCs hooked up, so I have been able to try both and verify that the problem is not in the CC.

There is an MPV-12 250 installed where I have 6 strings with 4 panels each (Abound Solar AB1-70 70W thin film). All 6 strings are wired into the combiner box and from there I have 10AWG wire running about 30ft (60ft round trip) to the Classic 200 (positive has a 20A breaker inline near the CC). That is 1/2 of the system, I will be hooking up an identical configuration to the 2nd Classic 200 next week. If I shut off all but one string (doesn't matter which string), then I still get the same voltage drop as I do when all strings are active, so I believe that eliminates any potential wiring issues on the roof (string side of the combiner box), which would isolate the "loose connection" to the wiring running from the combiner box to the CC...but I've triple checked it and it seems just fine...so I'm a bit stumped.

I checked the RFR codes and I am getting a code 1 or code 111...I also flashed the newest firmware today, and the problem remains.   

[dgd]

Assuming those PVs are well illuminated with sunlight when you see this behaviour then try changing the Classic mode from Solar to Legacy P&O solar mode.  This mode seems to work better when an array voltage droops near battery voltage when the Classic tries to take current from the array.
That #10 might be  ok but  I would change it to #6 or #4 gauge cable, with max pv power 12amps at 140volts I'd not want anything lost in the cabling.

dgd

[miahallen]

Thanks dgd...I'll give it a try.

At 10AWG, my loss should stay below 0.6% through that section of wire.  Going to a 4AWG wire increases my efficiency by 0.4%...not worth it IMO based on the cost of 4AWG wire here in Belize ($2.50US/ft or $264US for the system) 

[miahallen]

Tried the Legacy P&O mode, but the problem remains...if fact, it got slightly worse.  Input voltage hovers around 29V when in "Solar" mode and around 24V when in "Legacy P&O" mode.  Battery voltage hovers at about 24.2V in both modes.

[Halfcrazy]

You have tried 2 seperate classics?

One thing I have seen a couple times in our E-Panel is the PV- run to ground or AC Neutral not DC -

Can you confirm the PV- is either run to a common DC- or to the Classics PV- terminal block?

[miahallen]

Yes, there are two Classic 200s used in this system, both are showing the same symptoms...

I also double check the negative line, and it is attached to the DC bus bar as it should be (please refer to the picture attached), the blue arrows point to the BAT- connection on each of the controllers.  The white cable at the top of the bus connects to the DC shunt, the small black wire is connected to the Magnum battery sensor (DC powered).  So there doesn't appear to be any AC-DC link present per your suggestion.

[Halfcrazy]

Where are the PV negative leads?

WAIT it looks like there are 2 pieces of PV cable going to the Earth Ground bus bar? Are those the PV-? If so move them to the negative bus with the classic wires

Ryan

[miahallen]

No, the PV wires you see are for the equip ground...see this pic

[Resthome]

What model breaker are you using?  They look like Midnight AC DIN Rail breakers but maybe not.

[dgd]

Just some ideas...
That looks like AC mains wiring you have used for the PV input to breaker then to Classic. I doubt its #10 and its likely only 5 to 7 solid copper cores, untinned. This wiring tends to fracture and break quite easily, especialy if copper is nicked when the insulation is removed. Have you folded over and soldered the ends when they go into breaker, combiner and Classic?
I would suggest using proper tinned twin 6mm DC solar cable, multistrand with ends soldered
As a test I would also use another length of cable to temporarily connect one PV string directly to the Classic, no combiner, no breaker, make sure the string is in good sunlight not shaded, not an overcast or dull sunless day and double check the string wiring is good

                                 Panel 1                   Panel 2                 Panel3                Panel 4

     to Classic -ve  <-- Neg  Pos--------------Neg  Pos------------Neg  Pos----------Neg  Pos-----> to Classic +ve

Sorry if this is obvious.  Use a voltmeter to check the combined voltage before connecting to Classic being careful as 140v can be dangerous.

dgd

[Halfcrazy]

Also it looks like you have the blue wire hooked to the breaker in correctly. There should be a copper jumper in the bottom of the breaker so all connections will be in the top. There is a + and a - emblem. The PV+ goes tot he + emblem and the - emblem goes out to the Classics PV +

[miahallen]

Thank you for the replies dgd and HC...I spent some time on Skype with the equipment vendor today, and we discovered my incorrect breaker wiring and corrected the issue.  Unfortunately, that did not resolve the symptom I am experiencing.  I have already planned to try different wiring tomorrow morning, sun is in the forecast, so we should be able to make some progress.

pictures of the rewired breakers attached

[Halfcrazy]

So what I would do is watch the PV side of the combiner breaker with a volt meter. Lets see if the PV strings are doing the same thing as the classic

[miahallen]

Yes, they are...checked at the combiner box, and the breaker below.

[Halfcrazy]

And the voltage is drooping to battery voltage all the way up the line? We could try putting the Classic in Uset VOC at 75% and see if they do anything?