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
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
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
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
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
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.
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
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
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
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:
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
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
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
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.
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
Quote from: mike90045 on March 25, 2019, 02:26:28 AM
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
1. These are 50-100 year panels. Glass on Glass, using high efficiency mono cells.
........I don't think commercial panels can even compare.....
2. I don't see how the batteries have completed bulk......given the low voltage of the bank.
3. The charger SAYS it's in Bulk............
Now, if I put a heavy load on the system, THEN there would be somewhere for the power to go, correct?
z
Quote from: Resthome on March 25, 2019, 03:04:30 AM
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.
The readings were taken at different times of day..........
Bottom Line: Before I was getting about 25% of the array capability......now I'm getting 50%, using Legacy P+O mode.
z
I'd REALLY like an explanation of why this happened:
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.
z
I read somewhere that if the solar output voltage is below the battery volts, then the Classic would operate like a PFM .......is that correct?
Cause I could change the Battery voltage to 36 .....
z
Quote from: Zardiw on March 26, 2019, 10:26:00 AM
I read somewhere that if the solar output voltage is below the battery volts, then the Classic would operate like a PFM .......is that correct?
Cause I could change the Battery voltage to 36 .....
z
The Classic will sit in Resting Mode until the input voltage reached approximately 130% of the battery voltage set point 48 x 133% = 64 volts This is the point that the Classic will try to start BULK. If there is enough power coming into the Classic, it will stay in BULK and drive to ABSORB voltage. If for any reason there is not enough power to stay in BULK the Classic will go back into RESTING mode and try again as the voltage rises.
Quote from: KyleM on March 26, 2019, 10:34:07 AM
Quote from: Zardiw on March 26, 2019, 10:26:00 AM
I read somewhere that if the solar output voltage is below the battery volts, then the Classic would operate like a PFM .......is that correct?
Cause I could change the Battery voltage to 36 .....
z
The Classic will sit in Resting Mode until the input voltage reached approximately 130% of the battery voltage set point 48 x 133% = 64 volts This is the point that the Classic will try to start BULK. If there is enough power coming into the Classic, it will stay in BULK and drive to ABSORB voltage. If for any reason there is not enough power to stay in BULK the Classic will go back into RESTING mode and try again as the voltage rises.
Thank You!
Now, if the Classic is in 'resting' mode........will the readings in the Midnite Solar Status Panel software read as 0 on the Watts and Battery Amps?
Cause that has never happened.....
z
Z's system is 24V not 48V...
It's 1.33 X battery voltage -1.0 volt as I remember...
So, 1.33 X say, 27V would be 35.9V and -1.0V would be 34.9V
So, 35V or 36V should be on the edge but OK.
So, this chart, which adding up all of the Isc values gives you about 26 amps...
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
....Doesn't necessarily mean you are going to get Isc at the Vmp voltage. Imp should be kind of close to the Isc but not exactly. Some panels will be more different than others
You could try this and use the real amp-probe that you used for measuring short circuit current so that doesn't vary...
Measure Isc of ONE panel and the Voc of that panel.
Then, measure the current of that one panel at the Vmp that the Classsic finds and also note that voltage and current.
The Vmp that the Classic finds should be somewhere between 76% and 82% of the panels' Voc measurement.
The power will be the Vmp times the Imp of course. But this will at least show you what you SHOULD get out of the panel.
You can tweak the Vmp when in MPPT mode (Bulk, Float MPPT), up and down by pressing the soft-left or soft-right keys.
i.e. The upper left and upper right keys while in the main status screen to make sure that you are really at the Max Power point.
Interested to hear what you find.
boB
Hi z,
Well, you DO understand that PV modules are specified with cell temperatures of 25 C -- 77 F, with 1000 watts/ sq meter of illumination, using a flash tube.
In full midday sun, we can have, at best about 1 kW/sq M, but the sun heats the cells. So at solar peak in full sun most PVs produce about 75 - 77% of this maximum specified amount of power. Less power at lower sun angles and with the sun not directly at 90 degrees to the sun.
Do not know about the cells that were used to make your PVs, but it is not uncommon for the cells that one can buy on the market (on e-bay, etc) to be cells that do not quite pass final power tests, or have other defects. Of course it is not possible to know the specs of each cell that are in your PVs.
So taking measurements can be a bit difficult, due the variables that come into play with the exact setup of each PV that one is measuring, individually.
Most PVs are manufactured by robots, this can help make PV modules more consistent than PVs that are made by hand, etc.
FWIW, IMO, etc, Vic
Zardi,
With home built panels there are many factors that are not considered. Take the glass.....there is many varieties from iron containing window glass to water white to specialty solar hi transmissible glass etc. same with the bond between the glass and the glass. How many bypass diodes....etc. every detail needs to be considered.
I have never heard of any manufacturer offer a 50-100 year panel. I have a few that have survived the sun in the Arizona desert for over 30 years and the are very dog eared ,burnt, cracked cells, etc. These were built by a major forerunner to the present industry. There is an government agency here in California that approves panels to be used in code approved installations. They publish lists of acceptable panels and other lists of panels that have been decertified....including BP SOLAR! Hundreds of manufacturers that did not make the grade. Some of these companies poured millions into R&D.
I have 26 Sharp panels and they do not vary .1 volt or .1 amp from each other. Same for my 60 Sanyo HIT panels....very little variation between panel to panel...same for my Suntech panels....ditto for the antique Seimens SM-55's that are now owner 30 years old. And dog eared with burnt brown cells and cracks.
I do not think that any home builder can match the production process of a major manufacturer. They computer match cell by cell and separate them into groups. That is exactly why Sharp offers NE-165, NE-170, NE-180, NE-190, no they don't deliberately make 165 watt panels when the same production process can crank out the 190 watt ones. They weed out cells and make matching sets using computerized automated testing to sort the cells to be matched. The worst cells are sold by the lot to middle men and they land up on eBay. There is a lot of engineering going on there. I've been there, I've seen the process, it's way beyond my abilities and I have done many years in electricity and high end electronics.
That said it is understandable that each of your panels do not produce the same power. There are way too many variables to get a consistent result.
I have done several 2-4 kW 24 volt systems using the most commonly available panels...the 60 cell grid-tie type. I use them in strings of 2 for a MPP of about 60 volts. Never had an issue doing this even though the standard for 24 volt use is the 72 cell panel in strings of two.
Two of my main banks are all parallel 96 cell Sanyo HIT panels on my 24 volt systems, pretty rare to have a 2kw array all parallel. Sometimes when in very fowl weather I need to switch from solar mode to Legacy P&O to get maximum power. I'm right on the coast looking at the Pacific Ocean with the Santa Cruz mountains to my back so my weather is very variable here...very dynamic! I harvest more than enough power even on days where I don't see the sun all day. I'm very hands on with my systems.
I didn't get to here in a day or so....I haven't had a utility connection for over 20 years. There is a learning process. BTW...I was born in backwoods Alaska way off grid.....born off-gridder! Upper Matanauska-Susitna Borough...looking out at Denali Mount.....and yeah I miss it. If I could get decent medical care there I would retire there. Except in winter.....
Try some patience and understanding. This is not plug and play!
david
Quote from: Vic on March 26, 2019, 09:11:36 PM
Hi z,
Well, you DO understand that PV modules are specified with cell temperatures of 25 C -- 77 F, with 1000 watts/ sq meter of illumination, using a flash tube.
In full midday sun, we can have, at best about 1 kW/sq M, but the sun heats the cells. So at solar peak in full sun most PVs produce about 75 - 77% of this maximum specified amount of power. Less power at lower sun angles and with the sun not directly at 90 degrees to the sun.
Do not know about the cells that were used to make your PVs, but it is not uncommon for the cells that one can buy on the market (on e-bay, etc) to be cells that do not quite pass final power tests, or have other defects. Of course it is not possible to know the specs of each cell that are in your PVs.
So taking measurements can be a bit difficult, due the variables that come into play with the exact setup of each PV that one is measuring, individually.
Most PVs are manufactured by robots, this can help make PV modules more consistent than PVs that are made by hand, etc.
FWIW, IMO, etc, Vic
Thank you Vic.......
But you're missing the point........getting into the thicket of temperature, sun angle, PV efficiency, etc.
The POINT is that I'm getting not even CLOSE to what these panels are putting out.
And fwiw, these are 19-21% MONO 6x6 cells.....that came Boxed from the manufacturer........
Explain how a panel that has a Voc of 37v and a short circuit Amp reading of 6 something is only putting out 92 watts from the controller........THAT is the POINT.
z
Quote from: Zardiw on March 26, 2019, 10:18:36 AM
Quote from: Resthome on March 25, 2019, 03:04:30 AM
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.
The readings were taken at different times of day..........
Bottom Line: Before I was getting about 25% of the array capability......now I'm getting 50%, using Legacy P+O mode.
z
Hi z,
It seems that some of the "data" was taken at different times of day.
We all are trying to help. We wind up trying to do a bit of guessing, just what is going on, you are our reporter ... I was just attempting to remind you about some of the obvious variables, and possible effects of on measurements you were mentioning.
Sorry about not doing my "job" of explaining exactly what is going on ...
You seemed disappointed in the performance of the Morningstar MPPT CC -- low output power.
You seem disappointed in the Classic for the same reason. One consistent part of this equation might be something related to the PVs. Or perhaps expectations for PV power production at times of day when the Irradiance is low for varying reasons.
Was just trying to toss out some of those possible factors, in case you were not considering them.
Voc is not a very useful number to gauge potential PV power production. It is easy to measure, though. Vmp is not quite so easily measured, of course.
Anyway, good luck, Vic
Quote from: tecnodave on March 26, 2019, 11:06:27 PM
Zardi,
With home built panels there are many factors that are not considered. Take the glass.....there is many varieties from iron containing window glass to water white to specialty solar hi transmissible glass etc. same with the bond between the glass and the glass. How many bypass diodes....etc. every detail needs to be considered.
I have never heard of any manufacturer offer a 50-100 year panel. I have a few that have survived the sun in the Arizona desert for over 30 years and the are very dog eared ,burnt, cracked cells, etc. These were built by a major forerunner to the present industry. There is an government agency here in California that approves panels to be used in code approved installations. They publish lists of acceptable panels and other lists of panels that have been decertified....including BP SOLAR! Hundreds of manufacturers that did not make the grade. Some of these companies poured millions into R&D.
I have 26 Sharp panels and they do not vary .1 volt or .1 amp from each other. Same for my 60 Sanyo HIT panels....very little variation between panel to panel...same for my Suntech panels....ditto for the antique Seimens SM-55's that are now owner 30 years old. And dog eared with burnt brown cells and cracks.
I do not think that any home builder can match the production process of a major manufacturer. They computer match cell by cell and separate them into groups. That is exactly why Sharp offers NE-165, NE-170, NE-180, NE-190, no they don't deliberately make 165 watt panels when the same production process can crank out the 190 watt ones. They weed out cells and make matching sets using computerized automated testing to sort the cells to be matched. The worst cells are sold by the lot to middle men and they land up on eBay. There is a lot of engineering going on there. I've been there, I've seen the process, it's way beyond my abilities and I have done many years in electricity and high end electronics.
That said it is understandable that each of your panels do not produce the same power. There are way too many variables to get a consistent result.
I have done several 2-4 kW 24 volt systems using the most commonly available panels...the 60 cell grid-tie type. I use them in strings of 2 for a MPP of about 60 volts. Never had an issue doing this even though the standard for 24 volt use is the 72 cell panel in strings of two.
Two of my main banks are all parallel 96 cell Sanyo HIT panels on my 24 volt systems, pretty rare to have a 2kw array all parallel. Sometimes when in very fowl weather I need to switch from solar mode to Legacy P&O to get maximum power. I'm right on the coast looking at the Pacific Ocean with the Santa Cruz mountains to my back so my weather is very variable here...very dynamic! I harvest more than enough power even on days where I don't see the sun all day. I'm very hands on with my systems.
I didn't get to here in a day or so....I haven't had a utility connection for over 20 years. There is a learning process. BTW...I was born in backwoods Alaska way off grid.....born off-gridder! Upper Matanauska-Susitna Borough...looking out at Denali Mount.....and yeah I miss it. If I could get decent medical care there I would retire there. Except in winter.....
Try some patience and understanding. This is not plug and play!
david
Thank you Dave!
That all makes sense......I realize that a panel is only as good as it's weakest cell...
So commercial panels can be 'better' from that standpoint.
What I don't understand is why the power reported by the controller is so much LESS than what I'm measuring when I test each panel separately, and add it up.
It's partially overcast here, so I can't run my tests........the highest watt output today was at 1500 watts for a short time.....which is getting close to what I would expect....but still over 500 watts shy.....
I'll run extensive tests both with my Fluke DC Amp meter, and various configurations, both series and parallel and report back.......Will have to wait for a nice sunny day here in Palm Springs....which usually wouldn't be a problem.....lol.......except this year has been very strange weather wise.
The purpose of this system is also to go as much off grid as possible.....I like watching my electric bill decrease.
This is also not grid tied in any way.....and I don't want it to be.....I have a 50 amp relay that completely separates the grid from solar.....it's either one or the other.
But I'm slowly moving stuff over to the solar side .....to the inverter.....so far I've got some refrigerators and freezers totally running off solar......fwiw.
Anyway, thanks again for the input.......I'll report back with more info soon......
z
Quote from: Vic on March 27, 2019, 11:39:53 AM
Quote from: Zardiw on March 26, 2019, 10:18:36 AM
Quote from: Resthome on March 25, 2019, 03:04:30 AM
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.
The readings were taken at different times of day..........
Bottom Line: Before I was getting about 25% of the array capability......now I'm getting 50%, using Legacy P+O mode.
z
Hi z,
It seems that some of the "data" was taken at different times of day.
We all are trying to help. We wind up trying to do a bit of guessing, just what is going on, you are our reporter ... I was just attempting to remind you about some of the obvious variables, and possible effects of on measurements you were mentioning.
Sorry about not doing my "job" of explaining exactly what is going on ...
You seemed disappointed in the performance of the Morningstar MPPT CC -- low output power.
You seem disappointed in the Classic for the same reason. One consistent part of this equation might be something related to the PVs. Or perhaps expectations for PV power production at times of day when the Irradiance is low for varying reasons.
Was just trying to toss out some of those possible factors, in case you were not considering them.
Voc is not a very useful number to gauge potential PV power production. It is easy to measure, though. Vmp is not quite so easily measured, of course.
Anyway, good luck, Vic
Sorry Vic.......this is pretty frustrating and I really appreciate all the help..........didn't mean to come off the way I apparently did.
You're right....both the Morningstar MPPT and the Classic seem to be putting out much less power than I expected.
However, the Tristar 45 PFM was putting out a Lot more power........I had no readings from that, but went by the rise in battery voltage during the day.......it easily got to 29 and even 30 volts....
When I use MPPT, I'm lucky to get to 27 volts.
I know it's getting warmer, and I'm using more power......and I have no hard data to back that up as in readings, etc........but by now I have a 'feel' for my system, and I can tell the difference between MPPT and PFM .......which is leading me to believe that MPPT is a myth.......lolol.
Again, sorry if I was abrupt .....I really DO appreciate the help.....
z
PS. If anybody is curious as to how I'm building these panels......I have a YT series. First one:
https://www.youtube.com/watch?v=CuL-3msNpZ0&t=114s
Quote from: Zardiw on March 27, 2019, 06:13:57 PM
What I don't understand is why the power reported by the controller is so much LESS than what I'm measuring when I test each panel separately, and add it up.
z
What is the maximum power point voltage for each module and how much power was that at each of those voltages ?
One issue besides your Vmp being low is that each module's Vmp is different. If they are much different then you will only get an average Vmp.
For your system you will definitely want to use Solar O&P mode for tracking until you know that solar tracking mode is correct for this low voltage system.
Adding panels in series, and especially two or 3 panels that are similar power and current output but different Vmp's will be tracked better in series.
boB
Quote from: Zardiw on March 27, 2019, 10:19:01 AM
[
I looked at your first post where you said what your battery is
"And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's) "
What is your Absorb, Absorb time , and Float setpoints ?
When you are expecting the most power to come in do you have your system fully loaded with devices that will draw more power than your panels are capable of ?
My thought is that you can only force so much power into that small set of batteries and if you don't have loads on your system you won't be able to see the potential amount of power available.
I didn't reread all the comments before this one to see if this has already been discussed.
Larry
Larry I do not think Zardi is aware that the only time you get Max Panel output is when the bank is well depleted, say >50% DoD , like when the batteries have a minimized amount of resistance to the charge Volts and Amps...
> Also took a FLuke DC Amps reading.....it was late in the afternoon........but only 16.9 Amps......shoulda been at least twice that.
Late afternoon, my reliable 3Kw array puts out 900w. The sun angle is so lousy, the glass is acting like a mirror.
Quote from: Zardiw on December 31, 1969, 11:18:57 PM
Sorry Vic.......this is pretty frustrating and I really appreciate all the help..........didn't mean to come off the way I apparently did.
You're right....both the Morningstar MPPT and the Classic seem to be putting out much less power than I expected.
However, the Tristar 45 PFM was putting out a Lot more power........I had no readings from that, but went by the rise in battery voltage during the day.......it easily got to 29 and even 30 volts....
When I use MPPT, I'm lucky to get to 27 volts.
I know it's getting warmer, and I'm using more power......and I have no hard data to back that up as in readings, etc........but by now I have a 'feel' for my system, and I can tell the difference between MPPT and PFM .......which is leading me to believe that MPPT is a myth.......lolol.
Again, sorry if I was abrupt .....I really DO appreciate the help.....
z
PS. If anybody is curious as to how I'm building these panels......I have a YT series. First one:
https://www.youtube.com/watch?v=CuL-3msNpZ0&t=114s
Hi Zardiw,
Yes, we do sense your frustration. Most of us have been in similar situations to yours, many times.
Was not trying to be too snarky. Trying to get to the bottom of these types of issues can also be a bit frustrating for all of us ...
Also, it becomes more and more difficult to keep track of all of the details in one of these Threads, as they progress. Some are involved in a number of Threads here, AND on other Forums. So, as things progress, often, one really needs to re-read the entire Thread to sync with an individual's situation before composing a reply ... this is obvious.
So thank you for the added info on your PVs and the Link to your construction project. Will try to look at that soon.
I apologize for being a bit short in the previous Reply.
You will get your situation figured out. Good luck, and have FUN. Thanks, Vic
Quote from: ClassicCrazy on March 27, 2019, 08:48:41 PM
Quote from: Zardiw on March 27, 2019, 10:19:01 AM
[
I looked at your first post where you said what your battery is
"And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's) "
What is your Absorb, Absorb time , and Float setpoints ?
When you are expecting the most power to come in do you have your system fully loaded with devices that will draw more power than your panels are capable of ?
My thought is that you can only force so much power into that small set of batteries and if you don't have loads on your system you won't be able to see the potential amount of power available.
I didn't reread all the comments before this one to see if this has already been discussed.
Larry
Thank you Larry........at present the load on the system is minimal..........some freezers and refrigerators......so they only come on periodically, and don't draw that much current......
Does the Solar Status Panel software application reflect the power that is coming out of the controller?......cause that's what I'm basing everything on......for instance right now, early in the morning, it's showing 606 watts and 22.8 Amps..........which is halfway decent, but still not what the panels should be putting out.....in theory.....lol....
z
Quote from: Westbranch on March 27, 2019, 11:14:10 PM
Larry I do not think Zardi is aware that the only time you get Max Panel output is when the bank is well depleted, say >50% DoD , like when the batteries have a minimized amount of resistance to the charge Volts and Amps...
I did consider that.......was thinking that the more charge the batteries have, the more 'resistance' to charging there is.......
But I can flip a switch and put quite a bit of load on the system from the parts of the house that are currently connected to the grid........
Would that draw more current from the panels through the controller?
The power company is gonna cut power this morning for about 2 hours........will be interesting to see my entire house running off the solar system..........
z
Quote from: Vic on March 28, 2019, 03:14:37 PM
Quote from: Zardiw on December 31, 1969, 11:18:57 PM
Sorry Vic.......this is pretty frustrating and I really appreciate all the help..........didn't mean to come off the way I apparently did.
You're right....both the Morningstar MPPT and the Classic seem to be putting out much less power than I expected.
However, the Tristar 45 PFM was putting out a Lot more power........I had no readings from that, but went by the rise in battery voltage during the day.......it easily got to 29 and even 30 volts....
When I use MPPT, I'm lucky to get to 27 volts.
I know it's getting warmer, and I'm using more power......and I have no hard data to back that up as in readings, etc........but by now I have a 'feel' for my system, and I can tell the difference between MPPT and PFM .......which is leading me to believe that MPPT is a myth.......lolol.
Again, sorry if I was abrupt .....I really DO appreciate the help.....
z
PS. If anybody is curious as to how I'm building these panels......I have a YT series. First one:
https://www.youtube.com/watch?v=CuL-3msNpZ0&t=114s
Hi Zardiw,
Yes, we do sense your frustration. Most of us have been in similar situations to yours, many times.
Was not trying to be too snarky. Trying to get to the bottom of these types of issues can also be a bit frustrating for all of us ...
Also, it becomes more and more difficult to keep track of all of the details in one of these Threads, as they progress. Some are involved in a number of Threads here, AND on other Forums. So, as things progress, often, one really needs to re-read the entire Thread to sync with an individual's situation before composing a reply ... this is obvious.
So thank you for the added info on your PVs and the Link to your construction project. Will try to look at that soon.
I apologize for being a bit short in the previous Reply.
You will get your situation figured out. Good luck, and have FUN. Thanks, Vic
Thank you Vic!
I am going to take detailed readings on everything today, if the skies remain clear.......will do that around noontime when output is maxed more or less.....
Will post the results......then maybe the situation will be more clear......
z
Took some readings today at High Noon, and these are the results:
Tomorrow I'll make some 2 panel strings and see what the results of that are.......
z
I would recheck panel 4 and 9, 3.6A and 3.7A when you have all panels ''performing" ( or is it UNderperforming ?) connected. Tthose deltas between individual and array output suggests a poor connection or ? issue ...
hth
Quote from: Zardiw on March 29, 2019, 11:43:44 AM
Quote from: ClassicCrazy on March 27, 2019, 08:48:41 PM
Quote from: Zardiw on March 27, 2019, 10:19:01 AM
[
I looked at your first post where you said what your battery is
"And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's) "
What is your Absorb, Absorb time , and Float setpoints ?
When you are expecting the most power to come in do you have your system fully loaded with devices that will draw more power than your panels are capable of ?
My thought is that you can only force so much power into that small set of batteries and if you don't have loads on your system you won't be able to see the potential amount of power available.
I didn't reread all the comments before this one to see if this has already been discussed.
Larry
Thank you Larry........at present the load on the system is minimal..........some freezers and refrigerators......so they only come on periodically, and don't draw that much current......
Does the Solar Status Panel software application reflect the power that is coming out of the controller?......cause that's what I'm basing everything on......for instance right now, early in the morning, it's showing 606 watts and 22.8 Amps..........which is halfway decent, but still not what the panels should be putting out.....in theory.....lol....
z
When your solar panels are tied to batteries you won't get the full power output of your panels unless the batteries are low and the Classic is in Bulk. Once it goes to Absorb it will hold the voltage steady at absorb setpoint by decreasing the current going into the batteries. So if you want to really know how much your panels are putting out you need to put more load on the system than they are capable of and you will see whatever the Local Status app says for output is the max power . If you have a Whizbang on your system and the shunt wired in correctly you can also see how many amps are going into the battery and how many are going to the loads.
Yes the batteries have an internal resistance. It is not like a grid tie solar system where all available power will always be going into the grid from PV panels.
Larry
Something bothers me about the calculated power...
What is meant by "Open circuit power" ???
There is NO power when the PV is open circuited. I don't suppose that you are calculating expected
power by multiplying some measured current by measured Voc ?
Quote from: boB on March 30, 2019, 08:23:27 PM
Something bothers me about the calculated power...
What is meant by "Open circuit power" ???
There is NO power when the PV is open circuited. I don't suppose that you are calculating expected
power by multiplying some measured current by measured Voc ?
boB, you may have hit on something here. Just how is he determining the capacity of his homemade PV panels? What and how is he measuring the panel? As boB said at Voc there is NO power. So he can not use Voc to calculate the expected wattage of his panels. In the first few post he indicated his 9 panel should be giving him 2100 watts and in another he indicated 1900 watts. Not sure how that was measured or determined.
From his chart looks like the Vmp the Classic is getting is 26-27 Vmp. Which is very close to his battery voltage.
I think his array is around 1400 watts to 1500 watts and his chart indicates he is showing around 1200 watts which would be about right.
Quote from: boB on March 30, 2019, 08:23:27 PM
Something bothers me about the calculated power...
What is meant by "Open circuit power" ???
There is NO power when the PV is open circuited. I don't suppose that you are calculating expected
power by multiplying some measured current by measured Voc ?
I took readings on each panel when they were not connected....in bright sun...... Voltage and Amperage.......I guess the Voltage when not connected is Voc ....or 'open circuit' I think.......I don't know what you call the amperage when you measure it when they're not hooked to the system......but I was getting around 6-7 amps or so.....
Since watts is V*A, I calculated about 37v x 6 amps is about 222 Watts.....
I'm just ball parking here, but when they were connected to the controller, they only get 60% or so of that....
See the spreadsheet I made.....
Edit. I used a VC890C volt/ohm meter to measure the amps..........
z
Quote from: Westbranch on March 29, 2019, 09:05:40 PM
I would recheck panel 4 and 9, 3.6A and 3.7A when you have all panels ''performing" ( or is it UNderperforming ?) connected. Tthose deltas between individual and array output suggests a poor connection or ? issue ...
hth
Thank you Westbranch........I will recheck them.......
But I disconnected all but 2 + 3 and had them in parallel, and was getting 343 Watts from the controller.......
When I hooked them up in series, I ALSO got 343 Watts.......although the Voltage went to 57....
So it made no difference at all in the power generated......
But I will make another panel, and then have 5 strings of 2 each.......at least there will be less loss from the wire run, and from what you guys say, the Classic will perform better......
Bottom Line is I think I'll keep the controller.....the main reason is it will put out close to 100 amps, so I can hook 20 panels to it (10 strings of 2 panels) at 57 volts and still stay under 100 amps.......
z
Quote from: ClassicCrazy on March 30, 2019, 02:18:26 PM
Quote from: Zardiw on March 29, 2019, 11:43:44 AM
Quote from: ClassicCrazy on March 27, 2019, 08:48:41 PM
Quote from: Zardiw on March 27, 2019, 10:19:01 AM
[
I looked at your first post where you said what your battery is
"And Battery bank is at 26.8V (24V System w/ 4 6V Trojan L16's) "
What is your Absorb, Absorb time , and Float setpoints ?
When you are expecting the most power to come in do you have your system fully loaded with devices that will draw more power than your panels are capable of ?
My thought is that you can only force so much power into that small set of batteries and if you don't have loads on your system you won't be able to see the potential amount of power available.
I didn't reread all the comments before this one to see if this has already been discussed.
Larry
Thank you Larry........at present the load on the system is minimal..........some freezers and refrigerators......so they only come on periodically, and don't draw that much current......
Does the Solar Status Panel software application reflect the power that is coming out of the controller?......cause that's what I'm basing everything on......for instance right now, early in the morning, it's showing 606 watts and 22.8 Amps..........which is halfway decent, but still not what the panels should be putting out.....in theory.....lol....
z
When your solar panels are tied to batteries you won't get the full power output of your panels unless the batteries are low and the Classic is in Bulk. Once it goes to Absorb it will hold the voltage steady at absorb setpoint by decreasing the current going into the batteries. So if you want to really know how much your panels are putting out you need to put more load on the system than they are capable of and you will see whatever the Local Status app says for output is the max power . If you have a Whizbang on your system and the shunt wired in correctly you can also see how many amps are going into the battery and how many are going to the loads.
Yes the batteries have an internal resistance. It is not like a grid tie solar system where all available power will always be going into the grid from PV panels.
Larry
Thanks Larry.......
I DID put quite a load on the system......like my toaster oven which draws 1500 watts.......but the output did not change at all.
Also, the batteries weren't fully charged at all....
SO I guess all I'm gonna get with the system running is a max of about 140 watts/panel.......kind of disappointing.....
z
Btw, Panel 1 is the first panel I made.......you should see that thing.......lol.....but it still puts out pretty decent power...
I will pair it with the weakest other panel I guess when I make the 2 panel strings......or maybe I should pair it with the strongest panel....but I guess it's all controlled by the weakest link in the chain....
z
Hi z,
YES, with PV that are not loaded, that IS Voc for the Irradiance and cell temperature at that time.
With PVs not connected to the system, you must have shorted the PV cables together -- a Short. This is Isc -- Short Circuit current.
Voc is not too useful in guessing what power might be produced, because at that voltage there can be no power produced.
Also, it is important to orient the PVs at right angles to the sun to get the best power production at that moment.
Vic
Quote from: Zardiw on April 01, 2019, 09:25:29 PM
Quote from: boB on March 30, 2019, 08:23:27 PM
Something bothers me about the calculated power...
What is meant by "Open circuit power" ???
There is NO power when the PV is open circuited. I don't suppose that you are calculating expected
power by multiplying some measured current by measured Voc ?
I took readings on each panel when they were not connected....in bright sun...... Voltage and Amperage.......I guess the Voltage when not connected is Voc ....or 'open circuit' I think.......I don't know what you call the amperage when you measure it when they're not hooked to the system......but I was getting around 6-7 amps or so.....
Since watts is V*A, I calculated about 37v x 6 amps is about 222 Watts.....
I'm just ball parking here, but when they were connected to the controller, they only get 60% or so of that....
See the spreadsheet I made.....
Edit. I used a VC890C volt/ohm meter to measure the amps..........
z
I see Vic just replied but I will finish this
If you have just your panel in the sun and not connected to anything and then put a wire between its positive and negative terminal - that is a short - and if you measure the current on that wire that will be the Isc which is short circuit current.
If you take that short circuit wire off and just measure the voltage with nothing connected that is the Voc voltage open circuit.
What I believe others are saying is that you can't take the Voc and multiply it by the Isc to get your maximum watts.
The Imp current maximum power is at a voltage much lower than the Voc . The Classic software searches for this point which can change - it is the maximum power point MPPT .
So from what I think you are saying is that you are multiplying Voc by Imp and using that as your PV power rating . That is not correct .
Larry
Larry,
I am totally stealing this explanation 8) 8) 8) just wanted you to know I might take credit for it too :P
Kyle
To add to this, if you measure the VOC generally speaking a good rule of thumb is VMP will be 75% of VOC, So now with VOC you can calculate VMP and multiply it by ISC and get a close value to what you may expect for wattage.
In a nutshell in my opinion the issue, in this case, is low voltage, if this was my system I would wire two of those modules in series, With homebrew modules or mismatched modules I also would use Legacy P&O
Quote from: Zardiw on April 01, 2019, 09:25:29 PM
Quote from: boB on March 30, 2019, 08:23:27 PM
Something bothers me about the calculated power...
What is meant by "Open circuit power" ???
There is NO power when the PV is open circuited. I don't suppose that you are calculating expected
power by multiplying some measured current by measured Voc ?
I took readings on each panel when they were not connected....in bright sun...... Voltage and Amperage.......I guess the Voltage when not connected is Voc ....or 'open circuit' I think.......I don't know what you call the amperage when you measure it when they're not hooked to the system......but I was getting around 6-7 amps or so.....
z
With the amp meter connected across the terminals you are measuring Isc. and you are correct when the meter is in Voltage mode you are measuring Voc. Those measurements are not what is used to calculate typical system panel Wattage.
The Pmax is Vmp * Imp. See the specs on a typical manufactured solar panel and check out these values and the Wattage rating of their panels.
And observed panel output is typical 80% of Pmax at a nominal temp of 72-75 degrees of Vmp * Imp or the rating the manufacture specs as Pmax. With higher temp on the panels the wattage decreases even more.
Thanks Guys for those explanations.......looks like I was making some assumptions..........lol
z
Quote from: Zardiw on April 04, 2019, 03:46:22 PM
Thanks Guys for those explanations.......looks like I was making some assumptions..........lol
z
That's OK ! Been done before and will be done again in the future by many.
We'll help one at a time, no problem.
boB
Quote from: FNG on April 02, 2019, 11:27:36 AM
To add to this, if you measure the VOC generally speaking a good rule of thumb is VMP will be 75% of VOC, So now with VOC you can calculate VMP and multiply it by ISC and get a close value to what you may expect for wattage.
In a nutshell in my opinion the issue, in this case, is low voltage, if this was my system I would wire two of those modules in series, With homebrew modules or mismatched modules I also would use Legacy P&O
Thank You!
I built another panel, and now have 5 pairs in series: 1+2, 3+4, 5+6, 7+8, and 9+10
Here are the readings at High Noon:
Pair, Voc, Isc
1+2.......74.4v........7.30a
3+4.......74.7v........7.68a
5+6.......73.5v........8.02a
7+8.......72.1v........7.34a
9+10.....71.8v........7.63a
So if I take 75% of Voc, and multiply that by Isc, I should get a close value of what power the panels should put out.....is that right?
Because say on average, the Voc is 72v, times 75% is 54v times say avg Isc of 7.5a is 405watts/pair, times 5 pairs is 2025 watts.
So in theory I'm supposed to get 2025 watts...........is that correct?
But here are the readings in the Status Panel......with a good load on the system:
System is in Legacy P+O mode (what exactly is that?)
Input Volts - 48
Watts - 1614
Amps - 58.9
With the battery at 26.6v
SO I guess the power output is in the ballpark of what it's supposed to be......
Is that correct?
And thanks to everybody for helping with this.......hopefully it will help others to understand..
Time to build more panels.......more power!!........lol
z
I would say you are doing pretty good with the 1600 watts .
Remember also that the Classic is not 100% efficient in conversion .
Larry
Now you can compare those estimated watts to the actual harvest as recorded by the classic, but you will have to start the day with batteries that have been working after the sun went down and no loads while you are testing the panels...
have fun....
The measurement will be closer than before for sure but still not perfect....
The Isc will be kind of close to the Imp but will still be a bit higher than actual current at max power point (75% of Voc)
BUT there are more gothchas by using 75% of Voc and that might be from partial shading or possibly other factors.
One factor would be how well the panels match as far as Imp and Vmp.
Irradiance and PV panel temperature will be different from one time to another. i.e. the Isc you measure will more than
likely be higher or lower than when you actually place the panels back in circuit with the charge controller.
Best measurement is to use an ammeter and voltmeter from the PV into the charge controller WHILE it is operating.
Then you will be measuring the actual power into the controller. Assuming your current probe or clamp meter is
fairly accurate.
That is another aspect of this type of measurement... Measurement accuracy. It's not perfect.
Sounds like you are on your way to getting more meaningful results though !
boB
Of course we know boB is correct and is what I stated in my previous post. Power max = Vmp * Imp. You are using Isc and that is going to be a higher current than Imp. So NO your 2025 Watts is not the Power you are going to get from your panels it is going to be lower than that because Imp is going to be a lower value than Isc. And because your panels are all slightly different you are going to have slight differences.
Your best way is to measure your total panel output is while all your panels are connected to the controller and battery bank and have a large load on your system to get the max out of the system including all your wiring and connections. The controller can measure your Vmp and Imp. One of the status screens shows the total amps coming from you panels when at max power point.
You could put a clamp on amp meter around the negative PV lead going to the controller that will be your total Imp. Then measure the Vmp across you positive and negative PV leads while connected to the controller.
Again go back and look at how a typical manufacture specifies these values. I posted a sample spec for you to look at but all panels have this specifications and you can see how they get their panel wattage. Again manufacturers spec their wattage at a nominal temp of approx. 75 degrees. Panels in direct sun light are usually warmer. What most people see out of an off grid system is about 80% - 85% of the wattage specified by a manufacture.
I think your 1614 watts is a pretty good output for your system. Without a WBjr and shun you can't see how much of this is going to your batteries vs your loads.