Why is my system not performing?

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Why is my system not performing?

Postby bodger on Fri Nov 10, 2017 3:37 pm

Hello
I've just built an off grid house. My solar system was installed in April and has never produced much power. I have vfxr3048e, SM80, 3kw array, 915Ah traction battery. I'm not producing enough power to keep the battery charged. Even on a sunny day when the battery is low, the most I've seen it produce is 150watts! I've been keeping the charge up with the generator, but now i have finished the house I have the time to get to the bottom of the charging issue. The most its produced in a day is about 35Ah, and its often about 20Ah. The panels are in 4 strings of 3 and the max input voltage is normally about 101v. The battery voltage is normally between 46-48v and I switch the generator on every couple of days to keep the system charged. I'm only powering a few LED lights, computer, phones and a small water pump at the moment, (but will have washing machine, microwave, etc in the near future) so it should easily keep up with the demand. The voltage from each string of panels are roughly the same. Has anyone any idea what could be the problem or where I should start to look?
Thanks
Danny
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Re: Why is my system not performing?

Postby Mike Curran on Sat Nov 11, 2017 9:51 am

Danny - What is the make/model of your panels? Or, power rating per panel in watts, rated voltage and current for max output?

And what are the battery charging setpoints of your FM80 charge controller? Should be something like:

Absorb voltage: 58.8V
Absorb time: 4 hours
Absorb end amps: ~20A (consult your battery mfr's recommendation)
Float voltage: 52.8V
Current limit: 80A

I wouldn't mess with the MPPT settings on your FM80 - leave them at their defaults, at least until you figure out what's going on.

The size of your loads won't affect your PV system's output capacity. It should produce watts regardless of how many you're using.

- Mike
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Re: Why is my system not performing?

Postby bodger on Sat Nov 11, 2017 2:12 pm

Thanks for replying.
The 12 panels are Ecsolar ECS-250M60
Watts - 250w
Vmp - 31.4v
Imp - 7.92A
Voc - 37.2v
Isc - 8.3A

Battery charging set points
Absorb V - 57.6V
Absorb time - 1hr
Absorb end amps - 0A
Float voltage - 54.4V
Current limit - 80A
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Re: Why is my system not performing?

Postby Mike Curran on Sat Nov 11, 2017 5:45 pm

I guess I was expecting the answer to jump out at me with that info...Looks pretty normal. I wonder if maybe the panels themselves aren't wired the way you think they are, or maybe some connections aren't secure. It'd probably be worth taking a look into your combiner box, maybe even take a voltmeter (on a sunny day) and measure the incoming voltage from each series string, if you can isolate them easily.

Out of ideas... post your findings on the forum, somebody's got to have an idea what's wrong.
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Westinghouse Solar:
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Re: Why is my system not performing?

Postby blackswan555 on Sat Nov 11, 2017 8:44 pm

How long have the batteries been stored ? Presuming they are FLA? have you got a hydrometer and check SGs ? (If not get one)
Firstly your above charge voltage and time are to small, Absorb voltage: 58.6V Absorb time: 5 hours would be a better starting place, Also what are your gen charge settings ? If also at default? again to small, 58.8v & 4 hrs,
Both of these will need to be fine tuned once your batteries are run in (about 70 cycles) using SGs, (or other methods if not FLA)

But this is the bit that bothers me
Even on a sunny day when the battery is low, the most I've seen it produce is 150watts!
Next good day have a look at it, See what in and outs are, Then go switch something reasonable on in the house, eg about 1kw, and go have another look, If there is enough solar getting to the system it should ramp up by as much as it can to try to compensate, (pics of both would be helpful)

Tim
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Re: Why is my system not performing?

Postby bodger on Sun Nov 12, 2017 2:49 am

Here are the voltage readings for each panel and string. I hope it makes sense.took a couple of weeks ago
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A17EBE18-BA56-4A76-BFE0-3BB88FCA5894.jpeg
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Re: Why is my system not performing?

Postby bodger on Sun Nov 12, 2017 2:55 am

Tim,
Here is the Fm80 screen before the 1kw load is started
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FD7E0493-C115-48BB-8483-AF04F764FF69.jpeg
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Re: Why is my system not performing?

Postby bodger on Sun Nov 12, 2017 2:58 am

Here is the screen after the load is started. Not much change as far as I can see.
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B08C9174-F9D7-46BE-8A33-293E5C276E15.jpeg
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Re: Why is my system not performing?

Postby bodger on Sun Nov 12, 2017 3:42 am

Mike and Tim
I have adjusted the settings as you have both suggested, however the voltage never gets above 50v unless I start the generator. When I look back on the daily data screens, the system has never registered any time in float or absorb. I bought the the FlA battery second hand from a company that maintans fork lifts and are battery specialist. It was less than two years old and I had it for a year before I had it installed. The company that wired in the system it specialise in grid tied installations normally and know nothing about battery charging, and are reluctant to help find the fault. when I realised the system was not working correctly I thought it was either the panels not producing enough, the wiring, the battery or the charge controller. I spoke to the company that supplied the inverter and the charge controller and they were concerned that the panels were in 3 strings of 4 and the input voltage to the FM80 may have been going to high, which I didn't agree, but I got the installer to change it to 4 strings of 3 panels.
I got the battery man to come and check the battery over about a month ago and he replaced two suspect cells and then was happy that the battery was ok. He did say the PV wasn't putting enough into the battery. When he measured the voltage on a cell with the pv off and then switched the pv on the voltage went down. We turned the pv off again and did the same thing with the generator and the voltage went up. I checked the voltage on the strings and panels (see photo) and as they seem balanced I thought they seemed ok, although I didn't really know what to expect. So then I was thinking that the issue is either the FM80 faulty, maybe bad connections somewhere or possible the panels all performing poorly. The panels I bought second hand from someone who who had bought a pallet full. He said they had been installed somewhere and had been removed under warrenty as they were performing slightly below where they should have been, he said 5-10% down. He had used some in his domestic pv system, which he said were working well, and he was selling the ones he didn't need.

My hydrometer is broken, and I am going to get another one today, so I will check the SG's later.

I hope all this makes some sort of sense
Thanks again
Danny
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Re: Why is my system not performing?

Postby blackswan555 on Sun Nov 12, 2017 7:23 pm

By the FM pics, You are not getting enough incoming voltage to the charge controller, MPPT chargers need at least 3 v above battery to start to charge, ideally in a 48v system around 70v to 90v, Looking at your panel specs, 3 in series should be giving you that but the FM display tells a different story,
Have a look around for bad connections, And do a few more readings, (I am not sure I understand your above readings correctly,) Are those panels as good as he said ?

Tim
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Re: Why is my system not performing?

Postby bodger on Mon Nov 13, 2017 1:04 am

Do you think it may be worth buying three new panels, to replace one string with panels that I know I are ok, and if this is improves things then I know the panels are the problem and I can replace the rest? Is there fool proof way of testing that each panel is ok?
I'm going to go through every connection today.
Thank you
Danny
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Re: Why is my system not performing?

Postby blackswan555 on Mon Nov 13, 2017 1:09 am

If I am reading it correctly you have a (tested) VOC (no load) of about panel plate, I am guessing the other numbers are the VMP ( panels loaded) ?

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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Re: Why is my system not performing?

Postby bodger on Mon Nov 13, 2017 7:39 am

The top line of numbers Voc, I turned off the isolator for the string then measured the voltage at the terminals of each panel (they were still connected in series in the string). The next line down is the same, but with the isolator on, so connected to the FM80. The third line is voltage of the whole string with the isolator off, and the last line is the string voltage with the isolator on, so its connected to FM80 and charging.
I have just gone through all the wiring and plugs etc, and they all seem good.
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Re: Why is my system not performing?

Postby Mike Curran on Mon Nov 13, 2017 2:59 pm

I think your panels aren't producing as advertised. You may want to consider rewiring them 4 in series. That could be painful, I know... :sad:

If you ever replace them you may have to go back to 3 in series as new ones will be closer to their rated output.
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- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: Why is my system not performing?

Postby blackswan555 on Mon Nov 13, 2017 8:02 pm

Is there fool proof way of testing that each panel is ok?
If you have an amp meter capable of reading up to 10 amps DC or a clamp meter , yes, on a sunny day, If a normal meter you would place it in circuit with panel, eg short panel out with it, (but only briefly, your meter will not like it too much) do that for each individual panel, the readings should be more or less the same, If clamp meter, short panel and measure,
Readings, If it is anywhere near an STC day it should be near,ish shown on plate, eg on yours Isc - 8.3A, But STC days are rare, So as long as the readings between each panel are reasonably close, that is a good test,

But and it is quite a big But, From your above info most are so far away from what they should be reading I think they are scrap anyway, Even the best one in my estimation is 75%

Do you think it may be worth buying three new panels, to replace one string with panels that I know I are ok, and if this is improves things then I know the panels are the problem and I can replace the rest?
Yes, I would also test as above to find the very bad ones and ditch them now,
From above readings, the ones that are 16v ish VMP are already on the way to the skip, (I would suspect a fair few dead cells in them) As same as batteries, a string is only as strong as its weakest link, Those low voltage ones are the weak link & dragging every string down by the look of it,
edited to add,
If you do just add 3 new ones now, It will throw your MPPT all over the place, you will see an improvement, but not as much as matched would give,

Edited to add a bit more, Simple and straight to the point random weblink for normal meter, It is the isc you are looking for , https://www.solarpaneltalk.com/forum/of ... el-voc-isc


Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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Re: Why is my system not performing?

Postby bodger on Tue Nov 14, 2017 12:52 am

Thanks Mike and Tim
I think you're right, the panels look like the culprit. We haven't got a sunny day until Friday according to the forecast, so I will test all the panels then.

I can't really afford to buy 12 new panels at immediately, but I assume if all 12 are scrap, if I dumped them and just had one string of three new ones, which could produce up to 750watts, I will still be better of than I am now with 12 panels producing 150watts.

I am really greatful to both of you for your help.
Danny
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Re: Why is my system not performing?

Postby bodger on Tue Nov 14, 2017 1:24 am

I've just looked at the previous data and the highest peak amps ever was 3.3A. Most days about 2.5A. I suppose I should be seeing about 30-40A on a sunny day?
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Re: Why is my system not performing?

Postby klundquist on Tue Nov 14, 2017 9:10 am

bodger wrote:The top line of numbers Voc, I turned off the isolator for the string then measured the voltage at the terminals of each panel (they were still connected in series in the string). The next line down is the same, but with the isolator on, so connected to the FM80. The third line is voltage of the whole string with the isolator off, and the last line is the string voltage with the isolator on, so its connected to FM80 and charging.


What is the "isolator"?

What does the FM 80 show for Voc and Max Voc in the Stats Menu? (Press far left button under FM80 screen then point the arrow at Stats and press GO)

Have you checked polarity of all the PV strings? It seems like you have a possible wiring issue like a ground fault or incorrect polarity. This is assuming you get full sun on your PV array.

Simplify your troubleshooting by trying just one string of modules with the FM80 at a time. Force "BULK" on the FM each time you try a string of modules. (Press far left button under FM80 screen then point the arrow at misc, press NEXT, then press BULK). After you force the bulk charge the FM will track your PV string to see how much power it can find.

-Kurt
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Re: Why is my system not performing?

Postby bodger on Wed Nov 15, 2017 12:54 am

Hello Kurt
The Voc is 96.4
Max Voc is 144.6
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Re: Why is my system not performing?

Postby bluespur on Wed Nov 15, 2017 2:33 am

You quote
When I look back on the daily data screens, the system has never registered any time in float or absorb.
but the pic immediately above shows the controller in float. Are you meaning the daily data screens on the controller?
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Re: Why is my system not performing?

Postby bodger on Thu Nov 16, 2017 6:39 am

I took advantage of the good winter sun earlier today and disconnected my panels to test them. I tested the Voc which was between 34.0V - 36.1V per panel. I borrowed a clamp meter to measure the Isc. I plugged each panels positive and negatives together and put the clamp meter on and it didn't measure anything. I tested the meter on a known current somewhere else and the clamp meter worked fine. I tried the Isc another panel and it still didn't register anything. I un-shorted the panels and set my DVM to amps and measuered the current between the positive and negative. I got a reading of between 1.1A - 1.9A per panel using this method. The Rated Isc on the panels is 8.3A. Do these readings suggest that the panels are scrap?

Yes Bluespur, it does say float. I had been checking stuff out on the system and it had been doing a EQ charge from generator, and I had just disabled the EQ and it went to float.

Danny
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Re: Why is my system not performing?

Postby Mike Curran on Thu Nov 16, 2017 7:25 am

If you shorted them through your DVM and measured only 1-2 amps in bright sun, I'd say they're shot. Can't explain why the clamp-on meter didn't read this...also, haven't seen many DVM's rated to measure more than an amp or so through them. I'm old, though :smile:

FWIW
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- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar:
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

Re: Why is my system not performing?

Postby bodger on Thu Nov 16, 2017 11:43 am

Not great news but thanks Mike,
The DVM measures up to 10A.
Danny
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Re: Why is my system not performing?

Postby JRHill on Thu Nov 16, 2017 12:30 pm

Mike Curran wrote:If you shorted them through your DVM and measured only 1-2 amps in bright sun, I'd say they're shot. Can't explain why the clamp-on meter didn't read this...also, haven't seen many DVM's rated to measure more than an amp or so through them. I'm old, though :smile:

FWIW


How does someone get a whole batch of failed panels? Wouldn't the measurements be all over the place? Wouldn't the bolt holes show signs of being mounted before? Wouldn't the serial numbers correlate? Or even if below acceptable parameters, would not there be a dispersion between barely acceptable+ and trash? Something is not adding up.

I'm a QA guy and suspicious by nature. But I do know that there are things that are blamed that aren't necessarily at fault.
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Re: Why is my system not performing?

Postby blackswan555 on Thu Nov 16, 2017 6:43 pm

The panels I bought second hand from someone who who had bought a pallet full. He said they had been installed somewhere and had been removed under warrenty as they were performing slightly below where they should have been, he said 5-10% down. He had used some in his domestic pv system, which he said were working well, and he was selling the ones he didn't need.


Are you sure he did not say they were only producing 10% lol :smile:

But your readings are not good ,,,, Was the clamp meter AC & DC? Some (cheaper) ones are only AC, But your test with other meter confirms they are well down.

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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