Testing problems - please help

[WRDEnergy]

I am doing an install on a friends house which is identical to the one on my own house....

I have just finished putting all the panels up and wanted to test everything before I tidy up the cables... I tested each panel before I installed it just to make sure there was no problems.

I have run into an issue though... I tested the open circuit voltage on 8 panels (2 strings of 8) and got around 300 volts which is what I would have expect on a nice day like today... I then try to test the amp's so I short circuited everything and was only getting around 0.01 amps (basically nothing) when I would be expecting around 8 (ish)

I have checked all the connections and it seems strange to me that I am getting a voltage but no amp's perhaps someone has some idea's as to what I can do to find out the possible problem my mind has gone blank.

Thanks !

 

[prof. popkiss]

What kind of meter are you using to measure the current?

 

[yellowvanman]

How are you making the short circuit?

Like you I think if you've got a voltage you should get some current, so check the short circuit mechanism/procedure.

Did you check the voltage again after trying the short circuit? ie. voltage still good!

 

[WRDEnergy]

What kind of meter are you using to measure the current?

I am using a kewtech kt203

How are you making the short circuit?

Like you I think if you've got a voltage you should get some current, so check the short circuit mechanism/procedure.

Did you check the voltage again after trying the short circuit? ie. voltage still good!

yes I checked the voltage after and was still there. The meter I have does both amp's and volts have to use the clam for the amps I guess it is possible that part it broken.

To make the short circuit i am joining the + and - after the DC isolator it is the same meter I used on my course and I am 99% sure I am using it in the correct way. I also used this meter (although 5 days ago) to check each panel individual before I put them up on the roof (to try and avoid problems like this) and they where all fine....

any ideas would be appreciated

 

[yellowvanman]

Scaffolding still up, can you check one panel again? Just to make sure the clampmeter is working.

I assume you turn the dc isolator off, make a short ciruict (using what) and then turn the isolator back on. Best to go back to basics and work up from there.

 

[WRDEnergy]

Yeah the scaffolding is still here, I guess that's worth a try doing one panel and see if its working correctly.

and yes I do turn the isolator off make the the shirt circuit (using mc4 connectors) then turn it back on to measure it.

Thank you for your help I will let you know how I get on tomorrow if anyone else has been in a similar situation and found the issue please feel free to share !

 

[rb1]

I am using a kewtech kt203



yes I checked the voltage after and was still there. The meter I have does both amp's and volts have to use the clam for the amps I guess it is possible that part it broken.

To make the short circuit i am joining the + and - after the DC isolator it is the same meter I used on my course and I am 99% sure I am using it in the correct way. I also used this meter (although 5 days ago) to check each panel individual before I put them up on the roof (to try and avoid problems like this) and they where all fine....

any ideas would be appreciated

In response to yout meter we too have a Kewtech kt203 and had to return ours due to it being faulty so i'd try using another meter to see if your still getting the smae results

 

[gordysolar]

Did u try clamp meter other way it didnt say negative sign next to reading did it?

 

[morpheus75]

What is irradiance level? Voltage appears pretty much at any light level but current is light level dependent. Isc of panel times irradiance level divide by 1000 will give you expected reading


Sent from my iPhone using Tapatalk

 

[screwdriver]

Have you checked volts with isolator cover off? if so and you are now checking amps with the two ends coming out of the isoator have you considered a faulty isolator? we have had 2 in last few months.

 

[screwdriver]

bit dark to be doing it now obviously

 

[prof. popkiss]

You have a problem with either your meter or the circuit you're testing. It would be simplest to eliminate the meter first: a quick way to check this would be to clamp it around the earth lead from your car/van battery and switch the headlights on. You should obtain a reading of several amps.

 

[WRDEnergy]

ok so I have tried the meter on a single panel to test it and I am getting good voltage and amp readings so I think its safe to say at this point that the meter is fine.

Iradiance levels where fine I was getting around 700w/m2 at the time.

I guess it could be a faulty isolator but what are the chances of them both being faulty ? this morning I am not even getting a volate reading on either string. I guess it could be the isolator but whats the best way to check ? just a simple continuity check ?

I am now starting to think that:

1. maybe the isolator

2. maybe a cable problem

3. maybe a problem with the mc4 connections (although I checked these and they all looked fine)

anyone with any other ideas I will try and check the 3 I listed above.

 

[WRDEnergy]

If the only/best way to test an isolator is with a continuity tester (only thing I can think of) then the isolator is working how it should be..... this did however get me thinking.... could I not use a long lead from the end of the connection (i.e the bit just before the invertor) and to the furthest panel and use a continuity tester to see if I get a reading would that not let me know if there is a break in the connection somewhere and I can work my way back to find out exactly where the bad connection is (if there is one) or does using a continuity tester on solar panels mess them up in some way ? or not give you a reading altogether ?

 

[dansk]

Can you post the stats of the panel.

 

[moggy1968]

long lead, yes, you can do that, I've done it before to try and trace faults. If it's a connection problem you will have no voltage either.

I have also had a couple of faulty DC isolators. make sure it is functioning correctly. test the voltage coming out of the isolator. Also check you have wired that isolator correctly. I know that sounds stupid but they do vary. Also make sure your DC cables are correctly inserted into the isolator. We got caught like this one time when the lad had pinched the insulation putting the DC into the terminal on the outlet side.

 

[WRDEnergy]

Can you post the stats of the panel.

stats are :

Hyuandi s250mg
250W
Vmpp 30.5w
Impp 8.2A
Voc 37.5w
Isc 8.7A

long lead, yes, you can do that, I've done it before to try and trace faults. If it's a connection problem you will have no voltage either.

I have also had a couple of faulty DC isolators. make sure it is functioning correctly. test the voltage coming out of the isolator. Also check you have wired that isolator correctly. I know that sounds stupid but they do vary. Also make sure your DC cables are correctly inserted into the isolator. We got caught like this one time when the lad had pinched the insulation putting the DC into the terminal on the outlet side.

Isolator seems to be fine I am starting to think now that the problem must be when I short circuit at my end.... the connections I made there must have been bad (I hope anyway as easy problem to fix) I will have to wait till tomorrow to replace them but that's the only think I can think of as I have voltage again now

 

[moggy1968]

have you connected to the inverter yet?
I know you should test first but if you connect up (you know your polarity is ok) the inverter will give you a current rating. bit naughty but not really a drama.

 

[solarsavings]

Iradiance levels where fine I was getting around 700w/m2 at the time.
.

Seems high to me at this time of year.( it's been really bright here today yet only managed around 500Wm2

At the risk of pointing out the obvious if your lux reading is wrong............... it could explain the lack of amps

 

[dansk]

I was going to say the same, highest sort of readings for Isc ive been getting is between 1 and 2 sometimes less.

 

[WRDEnergy]

Should I not be getting some amp's though ? I have 2 separate radiance testers and was getting around 700w/m2 on both.

i mean it was a really nice clear day no shading at all on any of the panels getting about 300 volts can i really expect to get an amp level to low to read ? perhaps I am missing something but just does not seem right. This is only my second install though so I can admit mistakes are still there to be made and lessons still to learn I really do love everyone's help here as well such a great place !

I guess I could give a go tomorrow plugging into the inverter and see if that shows anything.

 

[moggy1968]

the rights or wrongs of the irradience readings are irrelevant in this case, it should still be reading higher than what you are getting. The worst I have had at about 1530 in december is about 0.1A so your readinga are definately too low

 

[WRDEnergy]

I got it working in the end !

I just had bad MC4 connections after the isolator when I was short circuiting them (my friend did that part and just used a normal crimp rather than a mc4 crimp and the metal terminals would not go in side the plastic correctly) thank you all for your help and suggestions I am glad I now have it working !

 

[screwdriver]

schoolboy error.... Never done it honest!!!!!

 

[moggy1968]

nah, me neither ;0)