Why the low power?

[Westbranch]

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...

[mike90045]

> 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.

[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

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

[Zardiw]

[

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

[Zardiw]

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

[Zardiw]

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

[Zardiw]

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

[Westbranch]

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

[ClassicCrazy]

[

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

[boB]

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 ?

[Resthome]

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.

[Zardiw]

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

[Zardiw]

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

[Zardiw]

[

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

[Zardiw]

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