I am a tech at a remote field camp in Alaska, we have a battery bank that is charged by a Honda generator and also have a solar array and Classic 200 to hopefully use less gas and keep the generator off during the day.
I was able to finally get the Classic working last summer then it stopped, tried again this year and still wouldn't charge so we replaced the Classic thinking it was an internal issue. Still having the same problem. It shows around 5 to 6 volts of input from the PV with the breaker off, at the same time the panels are producing around 60 volts or more with the sun out according to a voltmeter. As soon as I flip the PV breaker on the input goes up to 6 to 8 volts and when I put the voltmeter on the buss bar for the panels get the same voltage. Why is the power from the panels dropping?
We are charging 4 6 volt AGM batteries with 2 of each in series to make 12 volts then parallel to increase amperage; they are connected to a 1000 watt Magnum Energy inverter/charger that produces 110AC and also connects the generator for charging.
The solar array is 6 130 watt panels for a maximum of 780 watts.
I have been able to get bulk charging to turn on by adjusting the offsets under TWEAKS, -2.0 on battery and +5.0 on input will get the Bulk MTTP to turn on and then the input voltage goes to around 60 volts, amps stay at zero. Stays like this even as the sun goes down and hasn't produced any kWhr on the meter(last year during the short time it ran 1.7 kWh was added to the lifetime total to make it 19.1, so I don't think this system ever worked properly since installtion in 2020). If I go to status and hit enter the input voltage drops from the 6o volt range down to about 16 or less.
I was new to solar last year and have been learning as I go, at this point I am stumped and would appreciate any help. Thanks, Jeff
How do you have your PV wired ? Are you using a combiner box ? Did you test the breaker to make sure it is working ?
What I would do to diagnose the PV is disconnect from the system ( controller) and see what the open circuit voltage is . If you have a clamp meter you can short circuit the positve and negative and see what the current is. But you may not want to do that because you will get some arcing if your PV voltage is high ( when you separate the wires ) . You can test each panel individually same way and don't have to worry so much about arcing when voltage is lower. I am just wondering if you have a bad pv panel or wire or connector.
The voltages you see on the Classic are about what you would expect at night when there is no PV input - about half of the battery voltage which you said is 12v.
Larry
Quote from: ClassicCrazy on July 31, 2023, 09:57:56 PMHow do you have your PV wired ? Are you using a combiner box ? Did you test the breaker to make sure it is working ?
What I would do to diagnose the PV is disconnect from the system ( controller) and see what the open circuit voltage is . If you have a clamp meter you can short circuit the positve and negative and see what the current is. But you may not want to do that because you will get some arcing if your PV voltage is high ( when you separate the wires ) . You can test each panel individually same way and don't have to worry so much about arcing when voltage is lower. I am just wondering if you have a bad pv panel or wire or connector.
The voltages you see on the Classic are about what you would expect at night when there is no PV input - about half of the battery voltage which you said is 12v.
Larry
Thank you Larry, I have been thinking it is something with the panels with it dropping voltage under load. The breaker is fine, it was bad last year and after I replaced it the system was working for about a week then stopped. I have checked the open circuit voltage and getting the same 60+ volts as I do with the breaker off.
I wasn't the one that set the system up originally, so have to work with what I was given. No combiner box and not sure what that is but will look it up. I climbed up on the roof of the shed that holds the panels a couple days ago to check the connections. First one was a butt connector on the negative wire coming down from the panels to the buss bar, it was coming apart and not crimped well and I thought for sure I discovered the problem... fixed it and still the same. There were two more butt connectors on the roof and I replaced both just to be sure there was no corrosion. The rest of the connections are plugs between the panels in series, I suppose I should pull all of them apart, check for corrosion and reconnect them.
I like your idea of checking the current but I only have an older voltmeter here at camp without clamps, tools are somewhat limited but we have money in the budget and I should be able to get what I need. Really appreciate the advice. Thanks again, Jeff
Remove the PV+ positive wire from the Classic and measure the open circuit voltage of that + wire and negative. If the Classic is not bad, you will measure about the same 8V you measured before.
Or you can turn the PV breaker OFF and measure between negative (PV, battery -) and PV positive on the PV side of the circuit breaker. IF the PV is good, then you will measure some PV voltage that is above the battery voltage. (while the sun is shining of course)
IF it happens to turn out that the Classic IS bad and holding its input voltage down to that 6 to 8 volts... Then what you can do in a pinch is to connect the PV positive directly to the battery positive IF it is a lead acid batter and WATCH CAREFULLY the voltage at the battery terminals on the Classic. The Classic battery meter is probably working OK I presume.
So, this is how you can get those batteries up some BUT there will be no voltage regulation. IF you need to jump the system like this, just be careful that the battery voltage, as it gets charged, doesn't get too high of voltage over your normal Absorb voltage rating.
If these are lead acid batteries, you can go over a volt or two or even 3 for a little while. A minute maybe ? Just don't allow it to go up and up and up and up... Like a balloon. It won't be the best but can help some IF needed. Like drugs sometimes, it's an off label use.
We will check back tomorrow on this.
Hope it's a PV wiring or grounding issue or something easily fixable.
boB
Quote from: boB on August 01, 2023, 12:06:59 AMRemove the PV+ positive wire from the Classic and measure the open circuit voltage of that + wire and negative. If the Classic is not bad, you will measure about the same 8V you measured before.
Or you can turn the PV breaker OFF and measure between negative (PV, battery -) and PV positive on the PV side of the circuit breaker. IF the PV is good, then you will measure some PV voltage that is above the battery voltage. (while the sun is shining of course)
IF it happens to turn out that the Classic IS bad and holding its input voltage down to that 6 to 8 volts... Then what you can do in a pinch is to connect the PV positive directly to the battery positive IF it is a lead acid batter and WATCH CAREFULLY the voltage at the battery terminals on the Classic. The Classic battery meter is probably working OK I presume.
So, this is how you can get those batteries up some BUT there will be no voltage regulation. IF you need to jump the system like this, just be careful that the battery voltage, as it gets charged, doesn't get too high of voltage over your normal Absorb voltage rating.
If these are lead acid batteries, you can go over a volt or two or even 3 for a little while. A minute maybe ? Just don't allow it to go up and up and up and up... Like a balloon. It won't be the best but can help some IF needed. Like drugs sometimes, it's an off label use.
We will check back tomorrow on this.
Hope it's a PV wiring or grounding issue or something easily fixable.
boB
AS I mentioned previously, I have checked the PV voltage on an open circuit and behind the breaker that has been turned off: both getting around 60 volts or more with the sun out. As soon as I flip the breaker on the voltage drops to around 6 or maybe a little more, on the display and with a voltmeter.
This is a brand new Classic that was just installed, not trying to get it to work "in a pinch", want it to work as intended after spending several hundred dollars replacing the one we had.
I was wondering how the PV is wired - how many in series and how many parallel strings of those go into the Classic . Maybe you can do a line drawing of your system with the wiring to breakers, etc and post a photo of what you have there.
Larry
Is it possible that there is a short between the breaker and classic? Are the cables in metal conduit or laid across wood or something? What is the distance between the breakers and CC?
Just thinking of some possible trouble shooting areas. If you replace the classic once, it sounds like there is a different cause for the problem.
Ed
Quote from: Chilkat Weir on July 31, 2023, 10:46:45 PMQuote from: ClassicCrazy on July 31, 2023, 09:57:56 PMI like your idea of checking the current but I only have an older voltmeter here at camp without clamps, tools are somewhat limited but we have money in the budget and I should be able to get what I need. Really appreciate the advice. Thanks again, Jeff
This clamp meter will show DC amps and is not so expensive.
https://www.amazon.com/KAIWEETS-Multimeter-Auto-ranging-Temperature-Capacitance/dp/B07Z398YWF/ref=sr_1_4_sspa?crid=16G912PB9KZDI&keywords=kaiweets&qid=1690901228&sprefix=kaiweets%2Caps%2C2863&sr=8-4-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
The Classic is dead then if when PV connected it comes down to 6 volts or so.
I thought your battery might have been dangerously low.
Call or email support
- midnitesolar[.]com and we will get you another unit.
So sorry about this :-[
boB
Sounds like it may be a bad connection or breaker, Carries voltage but as soon as any load is put on it collapses. Seems unlikely you have 2 bad classics but I would suggest calling and talking to Todd 360-403-7207
Thanks everyone for helping.
Pretty certain it isn't the breaker, replaced that last year and have tested it this year, will check to be sure. The breaker is in a small box directly below the Classic.
I'm still thinking a bad connection between panels or possibly a bad panel. I will call Todd to see what he says.
Here's a diagram from a PDF that was drawn by the person that set everything up. One thing I just noticed is there is only one positive and one negative wire coming down from the panels to the buss bar on the shed. Need to track all the wires and see what is going on there.
(https://i.postimg.cc/wMNQMkXM/Screenshot-22.png)
Just for grins, I'd connect a load, a resistor or two, across the PV input wires, without connection to the classic, and see if the voltage holds up. It's entirely possible with a high input impedance meter, that the panels are reading voltage, but not producing enough current to charge the batteries. I've see this happen before. In fact, i have a couple of 175W panels that do the very thing. Open circuit voltage is 22V, but can supply only a few mAs of current. The panel's voltage drops like a rock when you load it down. I used a 8Ω 10w RESISTOR for a load.
It's worth a try...
mike
So, I just pulled all the connections between the panels apart, sprayed them with contact cleaner and added dieletric grease... no change. Checked the breaker again, it works, getting 58 volts on a cloudy day before and after the breaker.
I like that idea Mike but have no idea if I can find a resistor up here, definitely not something I have at camp. There is a Radio Shack in town.
Also the diagram I posted is wrong, all 6 panels are wired in series with positive and negative at each end going to the buss bar.
Will call support tomorrow, my work day is over. Thanks again all.
Thanks Mr. Weir for the drawing an checking back in. Todd is a pretty good troubleshooter.
Usually, if a Classic "breaks" (blows up FETs) the input will measure like, ZERO volts or at least less than 1 or 2 volts.
Another way that zero volts can happen is if the PV polarity is reverse.
But your system used to work, right ? If so, then it's not backwards and is wired correctly.
boB
Quote from: Chilkat Weir on August 01, 2023, 06:07:33 PMSo, I just pulled all the connections between the panels apart, sprayed them with contact cleaner and added dieletric grease... no change. Checked the breaker again, it works, getting 58 volts on a cloudy day before and after the breaker.
I like that idea Mike but have no idea if I can find a resistor up here, definitely not something I have at camp. There is a Radio Shack in town.
Also the diagram I posted is wrong, all 6 panels are wired in series with positive and negative at each end going to the buss bar.
Will call support tomorrow, my work day is over. Thanks again all.
Do you know what the Voc of the panels are ? There is usually a sticker on the back of them with the details. Are you sure they are all in series ? Because the voltage from PV you are seeing sounds more like three of the panels in series. Six in series would probably be around twice that voltage.
Larry
Quote from: ClassicCrazy on August 01, 2023, 06:57:27 PMDo you know what the Voc of the panels are ? There is usually a sticker on the back of them with the details. Are you sure they are all in series ? Because the voltage from PV you are seeing sounds more like three of the panels in series. Six in series would probably be around twice that voltage.
Larry
I just looked at his first post and it looks like his Voc is about 60 volts.
Also, the bus bars when the breaker is engaged shows the 6 to 8 volts that is present on the Classic PV input.
So I am pretty sure that the Classic is at fault here. It is kind of strange though that the input is sitting at around 6 to 8 volts. Usually when they blow, the input is pretty well shorted out.
boB
Hi all, finally getting back to diagnose this, been really busy counting salmon and training new workers.
I have the clamp meter that was suggested now and a couple 10ohm resistors.
First off, on a cloudy day today and with the sun much lower in the sky, the new multimeter is reading 110 to 119 volts coming from the 6 panels, never had that much with more sun when I last checked? For amps I am reading .55 to .66 and figure that is low due to the clouds maybe?
When I turn on the Classic, then switch on the PV breaker, voltage from panels drops but not as low as I was getting a couple months ago (6 to 8 volts). The "IN" on the display slowly rises from around 5.0 to 11.5 to 13.4 (battery at 11.6 volts), mostly stays resting but actually had it turn to Bulk MPPT for brief time, so it was charging but showing 0.0 amps. That tells me the problem isn't with the Classic?
For now, I am trying to diagnose the panels to see if one is faulty and we can replace it over the winter. Not sure if this is possible without a sunny day which is rare this time of year. Might have to wait until next year when the sun is overhead and bright.
To test them under load with the resistor, should I be checking voltage or current.
Appreciate and guidance, thanks.
It sounds almost as if there is a high source resistance in the solar array ?
Six to 7 volts with nothing connected to the PV input would show up as approximately half battery voltage. 6--7 volts could be that ?
I would check the PV wiring and make sure connections are good. It is possible that one defective panel could allow you to read full voltage Voc (~119V) but have VERY low power or current available.
The Vmp max power point that the Classic found was right above the battery voltage which kind of also points to high-ish resistance. 0.85 amps is pretty low too I think in Bulk MPPT mode... Kind of like it was dawn or dusk twilight
If wiring looks good (and measures good on an Ohmmeter ?), you might want to bypass each panel one at a time and see if it comes to life. Your Voc is plenty high enough at 119V for a 12 V battery so a bit less voltage should work... That is, if I understand everything correctly. :)
boB