Why the low power?

Started by Zardiw, March 24, 2019, 03:23:10 PM

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Zardiw

Just hooked up my Classic 150 and it doesn't seem to be working right.

It's High Noon, and measured individually, my (9) 66 Cell Panels put out about 60amps, or 2100 Watts.

Controller is in Bulk mode.

I've been monitoring it and here's what the Power Panel is showing me:

31 V --- 790-804 Watts --- 29.5 Amps
32 V --- 604-611 Watts --- 22.8 Amps
33 V --- 530 Watts -- 19.9 Amps

So the lower the voltage on the panels, the more power is being passed.....wtf....lol

And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's)

Would really like to know what is going on here........

And I can post a YouTube Vid if anybody wants to see for themselves........

Also.... I think my Tristar 45 PFM that I just replaced with the Classic was putting out more power..........

z
Faster horses, yw, ow, mm..........

Vic

Quote from: Zardiw on March 24, 2019, 03:23:10 PM
Just hooked up my Classic 150 and it doesn't seem to be working right.

It's High Noon, and measured individually, my (9) 66 Cell Panels put out about 1900 Watts.

Controller is in Bulk mode.

I've been monitoring it and here's what the Power Panel is showing me:

31 V --- 790-804 Watts --- 29.5 Amps
32 V --- 604-611 Watts --- 22.8 Amps
33 V --- 530 Watts -- 19.9 Amps

So the lower the voltage on the panels, the more power is being passed.....wtf....lol

And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's)

Would really like to know what is going on here........

And I can post a YouTube Vid if anybody wants to see for themselves........
z

Hi Zardiw,

Could you explain the three readings of voltage,   power and current?

You have 9 PVs,  or 66 cells (this is unusual),   Is the 31,  32 and 33 V the input voltage from some PVs?   Are there three individual parallel strings composed of three parallel PV?

If your PVs are essentially in parallel,   on a 24 V system,  this will not be a sufficiently high voltage to allow the Classic to find a the Power Point that uses the highest available voltage that equates to Maximum Power Point.

Here is a Link to the Classic String Sizer:
http://midnitesolar.com/sizingTool/index.php

What manufacturer and model number of your PVs?   Or the Vmp,  Imp,   Isc and Voc of your PVs?

Thanks,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Zardiw

Thank you for your response!

The voltage of the array just dropped to 28V for a minute or so and the power went to about 1100 watts.

All these readings are coming from the Midnite Solar Status Panel......that's running on my computer.....

I built these 9 panels.......and they have 66 cells each and are all hooked in parallel ......

I can build another panel, and hook 2 in series for increased voltage from 5 (sets).

Would the Classic then start using the power coming from my array??

Bottom Line: What you're saying is I'm better off with a PWM controller with the system as is correct?

And if I increase the voltage to 60+ V by hooking 2 panels in series and these 5 'sets' in parallel, would the MPPT produce more power than a PWM with 10 panels in parallel?

Thank you again for any info on this......

z






Faster horses, yw, ow, mm..........

Vic

#3
Hi z,

Yes,  any MPPT Controller needs more voltage headroom than  a PWM Controller.

You can wire these PVs as four strings of two PVs for now,   and the Classic will make considerably more poser than you are seeing now.

PWM  CCs have their place.    There is some "cost" in power to run the voltage converter in an MPPT CC,   But,  under many conditions,   a good MPPT CC,   or a GREAT one like the Classic will produce quite a bit more power that would a PWM CC.   AND,   the Classis is the utmost in flexibility and capability  --  so many options,   functions  and Advanced features,   compared to ANY other MPPT CC on the market  (IMO,   but this is all obvious to most).

With 66 cells, you will not be able to fully charge Flooded batteries,   on many days.  This is especially true with cool batteries,   when using high Absorb voltages,  or trying to EQ.

On warm days,   the Vmp falls with the heat,   and so on.    The exact details also depend upon the quality of the PV cells,   glass,   busbars,   etc.

Some of the above are guesses,   due to not knowing the exact specs on your PVs.

Have Fun,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Zardiw

The PV's vary but are all around 32-35V output.

You say I don't have enough voltage .....and the MPPT needs higher voltage.......

Then Why is it putting out MORE watts the lower the voltage.......lol....see the table I first posted..

I'm going to go outside and take some individual readings off these panels and report back.......

z
Faster horses, yw, ow, mm..........

boB

#5
What is the Voc of your PV array ?  The Vmp will normally be somewhere around 80% of the open circuit voltage.

It is looking like your Vmp or maximum power point voltage is really close to your battery voltage and this would be why it is requiring the input voltage to be so low.

Make sure that Low-Max (LoMax) is ON in the Tweaks menu.  It's the second menu in I think.  Having that on will make sure that the Classic can drop that voltage down closer to the battery voltage.

I would also use the Legacy P&O mode for such a low PV input voltage.

The better answer may very well be to re-wire the panels for higher Vmp and Voc

Let's check the Voc though first.

The PV array cannot put out any higher voltage than the Voc measurement at any given time and the Vmp will always be below that voltage.
That is why Vic is saying that you need higher voltage.


K7IQ 🌛  He/She/Me

Zardiw

#6
Here's some individual readings:

Voltage at array: 33.8v

         Voc
PV---Volts---Amps

1---36.2---5.93
3---36.2---7.32
7---35.1---6.44
9---34.8---6.51

Total of just 4 Panels individually: 26.2 Amps

Currently the Classic is showing 17.9 Total Amps at 32V

Pretty pathetic.............

z
Faster horses, yw, ow, mm..........

Zardiw

#7
Quote from: boB on March 24, 2019, 04:39:26 PM
What is the Voc of your PV array ?  The Vmp will normally be somewhere around 80% of the open circuit voltage.

It is looking like your Vmp or maximum power point voltage is really close to your battery voltage and this would be why it is requiring the input voltage to be so low.

Make sure that Low-Max (LoMax) is ON in the Tweaks menu.  It's the second menu in I think.  Having that on will make sure that the Classic can drop that voltage down closer to the battery voltage.

I would also use the Legacy P&O mode for such a low PV input voltage.

The better answer may very well be to re-wire the panels for higher Vmp and Voc

Let's check the Voc though first.

The PV array cannot put out any higher voltage than the Voc measurement at any given time and the Vmp will always be below that voltage.
That is why Vic is saying that you need higher voltage.

Voc of the Array is 36.2v ......and when it's hooked up it's 33.1v

The Classic is showing an array voltage of 32.7v.

There's about 100Ft run from the panels to the controller.......so losing a volt apparently.

Edit: Lo-Max was already on............How do I set the Legacy P&O Mode?

So far I'm kind of disappointed in the whole MPPT deal.......Right now I'm getting a lousy 538 watts......out of NINE panels.........lol

z
Faster horses, yw, ow, mm..........

Zardiw

OK........Just did an experiment.

Disconnected all panels except #2 and #3.

Measurement with only those 2 in parrallel:

V--30, Watts--224, Amps---8.7

Then I hooked 2 and 3 in series.

V--57, Watts--236, Amps---9.4

SO, Not much difference is there???

Maybe there's a bad panel?.........

Will hook/add  them up one at a time and see.....

But the problem obviously isn't the voltage being too low..........lol

z
Faster horses, yw, ow, mm..........

Zardiw

#9
I started with Panel 2 and added 1 panel at a time and noted the readings on the Solar Status Panel software.

When I added panel 8 there was NO change.

Disconnected 8 and added 9.......again no change.

Disconnected 9 and added 1........no change.

Added 8,9,1 and watts went up a little.

Also took Voc/Amp readings on each panel.

Also took a FLuke DC Amps reading.....it was late in the afternoon........but only 16.9 Amps......shoulda been at least twice that.

And each panel has 67 cells..not 66.......fwtfw.

See Images:

Faster horses, yw, ow, mm..........

ClassicCrazy

#10
Are those amp readings short circuit amps when you were testing the panels ?
You change the way the Classic charges in the Mode Menu on MNGP - go to where it says solar and you can use up down arrows to change to Legacy PO .

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Resthome

Quote from: Zardiw on March 24, 2019, 06:20:29 PM
OK........Just did an experiment.

Disconnected all panels except #2 and #3.

Measurement with only those 2 in parrallel:

V--30, Watts--224, Amps---8.7

Then I hooked 2 and 3 in series.

V--57, Watts--236, Amps---9.4

SO, Not much difference is there???

Maybe there's a bad panel?.........

Will hook/add  them up one at a time and see.....

But the problem obviously isn't the voltage being too low..........lol

z

Some thing is wrong with your system.

P=EI, so if you have 57v x 9.4A = 535.8W
John

10 x Kyocera KC140, Classic 150 w/WBJr, Link10 Battery Monitor, 850 AH @ 12v Solar One 2v cells, Xantrex PROwatt SW2000
Off Grid on Houseboat Lake Don Pedro, CA

mike90045

With homebrew panels, you have a lot of failure points that don't exist in factory panels, and
if your battery has completed bulk, there may not be anyplace for the power to go, so it's simply not harvested
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

Resthome

#13
Quote from: Zardiw on March 24, 2019, 04:54:01 PM
Here's some individual readings:

Voltage at array: 33.8v

         Voc
PV---Volts---Amps

1---36.2---5.93
3---36.2---7.32
7---35.1---6.44
9---34.8---6.51

Total of just 4 Panels individually: 26.2 Amps

Currently the Classic is showing 17.9 Total Amps at 32V

Pretty pathetic.............

z

I don’t understand your measurement. Here you indicate 4 panels putting out 26.2A. Yet in your photo you show each panel at approx 2.5A. Something does not add up. Hard to make any suggestions when the data provided is unclear.
John

10 x Kyocera KC140, Classic 150 w/WBJr, Link10 Battery Monitor, 850 AH @ 12v Solar One 2v cells, Xantrex PROwatt SW2000
Off Grid on Houseboat Lake Don Pedro, CA

Zardiw

Quote from: ClassicCrazy on March 24, 2019, 09:04:24 PM
Are those amp readings short circuit amps when you were testing the panels ?
You change the way the Classic charges in the Mode Menu on MNGP - go to where it says solar and you can use up down arrows to change to Legacy PO .

Larry

Yes, those amp reading are short circuit.....I disconnect the panel and test Voc and Amps.

Was able to find Legacy P+O, and now I show about 1100 watts max during the day.......lot better than 537.

Thing is, this array is putting out close to 2000 watts........and I'm only getting half that......

z
Faster horses, yw, ow, mm..........