Author Topic: 3 Strings Give No More Power Than 2  (Read 143 times)

Ron Swanson

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3 Strings Give No More Power Than 2
« on: July 08, 2020, 10:41:22 AM »
Strange one lately.  Customer bought off grid house knowing nothing about it.  Had problems, we showed up.  Fixed most problems but solar array behaves strangely.  3 strings of 3-SW300 panels into an Outback combiner and XW MPPT charge controller. 

Sun shining on panels, 900-1000 W is all the array produces.  Turn off any one combiner breaker, power does not decrease.  Turn off any two and power decreases to 450W.

Current measured on each string 3A with DC amp clamp.  Turn off one breaker, remaining strings increase to 4.5A.

Open circuit voltage ~112 or so per string.  Loaded voltage ~100VDC.  Isolated strings positive and negative, none grounded nor shorted to any others.

Thoughts?

Vic

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Re: 3 Strings Give No More Power Than 2
« Reply #1 on: July 08, 2020, 12:47:13 PM »
Hi Ron,

Briefly,   and you will know this:

Seems that there may be no place for the additional potential power to go.   Did you try placing a fairly large load on the inverter?

What was the CC charge state?  Battery voltage?
Perhaps the Current Limit in the CC had been set to a low value  ...

Did you try resetting the CC to Defaults?

Guessing done for now.   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

Ron Swanson

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Re: 3 Strings Give No More Power Than 2
« Reply #2 on: July 08, 2020, 10:23:24 PM »
This is a very lame system, logs from the controller max ever showed 1100W from this array.

Batteries are always low, therefore.

But thanks for being a sounding board.  It has made me wonder if the unit is limiting its output current for some reason.  It does seem to read correct battery voltage, about 52-54 in this case early in the morning.  No chance it had gone to float yet.

Is there a max charge amps setting in this thing somewhere?  I stepped through every menu I could find on the front panel of it and everything seemed normal there.

Vic

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Re: 3 Strings Give No More Power Than 2
« Reply #3 on: July 08, 2020, 11:13:03 PM »
Hi Ron,

From this manual:
https://solar.schneider-electric.com/wp-content/uploads/2018/01/ML201711_Conext-MPPT-60-150-Installation-and-Owners-Guide-975-0400-01-01_Rev-H_ENG.pdf

There is a Max Chrg Rate setting,  in Appendix B,   and a Restore Defaults,   but,   probably,   it requires the SCP (System Control Panel).   A multi-hundred $$  gizmo.   Gotta love Schneider,   always trying to sell added thingies and doo dads.

Good Luck,    Please let us know how things are going.    Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

Vic

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Re: 3 Strings Give No More Power Than 2
« Reply #4 on: July 09, 2020, 12:24:58 PM »
I know very little of the Schneider Solar stuff.

BUT,   it is possible that with the Schneider Combox,   these "Advanced" settings might changeable.

FWIW,    Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

boB

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Re: 3 Strings Give No More Power Than 2
« Reply #5 on: July 09, 2020, 12:49:11 PM »
Is there a current limit that is set low in the charge controller maybe ?
K7IQ

FNG

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Re: 3 Strings Give No More Power Than 2
« Reply #6 on: July 16, 2020, 01:19:55 PM »
Schneider does max charge in a percentage, I woul look for that and make sure its cranked to 100% (if thats acceptable) Also I believe they have a max current in the menus somewhere but i think you need the battery monitor for that

Ron Swanson

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Re: 3 Strings Give No More Power Than 2
« Reply #7 on: July 30, 2020, 12:08:26 PM »
You guys had it, they had set total charge current to 30% in the advanced menu.  100% was the correct setting for this application.