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No! The smaller string lays approx 3 meters below the bigger one !

What ! Are you really sure about that ? Well there are two ways to measure insulation resistance : 1.To short the positive and negative electrodes of the PV string, and measure the insulation resistance between the shorting point and earth. 2.Measuring the insulation resistance between the...

Well according to the manufacturer if the MPP voltage is not reached, current is generated but not too much

May i ask you what is 15s? If I connect only one string ( no matter which one ) the inverter connects to grid and starts working without any issue

AC side or DC side ? For the DC side I am using 4 mm2 DC cable up to 1000 volt

Well i am no longer sure that such thing doesn’t exist : Look at this one https://www.specialized.net/test-equipment/power-quality-analyzers/non-contact-volt-detectors/extech-381676a-pen-digital-multimeter-w-voltage-detector.html

@Zwy Thank you very much for this. A faulty isolation relay is a potential cause. if there is a sustained earth fault on the DC side, why the inverter would pass the morning check and starts producing power ?

@jimf909 @hwy17 I just found out that my digital clamp Meter measures only AC current !! I am looking online for a new clamp meter that can measure DC current as well, but before I buy one I want to ask you if you know a clamp meter that can also measure DC voltage in a contactless way : I...

- No ,i didn’t install it - String 1 ( 20 panels ) is on the house‘s roof While string 2 (10 panels ) is over the garage ( so only 10 panels could fit there ) - yes if strings are connected separately, there is no issue and inverter starts working smoothly after reboot

Hello! I have difficulty interpreting the result of the insulation’s resistance measurement I have done ( without short circuit ) : Testing the insulation resistance between the negative electrode and earth gave 2 Megaohm But testing between the positive and earth Showed OL on the...

Hi Does more voltage mean automatically more generated current ?

Thx but that doesn’t answer my question : I have two strings, one string has 10 panels and the other has 20 panels. The panels are the same and have the same specs. By looking at the output of each string, I notice that the bigger string ( that has more panels ) has a higher voltage but less...

Please look at my reply to &seneysolar I hope you could give some useful tips on this Thx

Well your previous explanation isn’t quite wrong : Both strings are connected in series, and the bigger one has quite longer wires than the smaller one !

okay, just wanted to say a big thank you for all the help ! I just measured the VOC voltage after shutting down the inverter and here are the results : String 1 had 310 Volt String 2 had 618 volt String 1 is still below the MPP threshold as it has only 10 panels. Then I turned on the...

@Zwy one additional info I forgot to add : Behind the inverter I have an AC breaker ( 3 poles !) Every time I shut down the inverter, i turn this breaker off ! I have a 3 phase inverter, do you think this is causing the problem ? Perhaps a 4 pole AC breaker ( for the neutral line also ) is...

but why should the MPPT reduce the current ? Isn’t that counter-productive ? The string that has 20 panels has a max VOC 620 volt while the smaller one has 320 volt, so in total 940 volt

Hello! I am a new member here, but i often come across to read interesting discussions on this forum. I have set up a solar system 5 years ago ( 20 Panels that are connected in series ) everything is up and running but a few weeks ago i started getting an earth Fault error on my string...

SGI 9K And what’s the MPPT operating range ? As i previously said the inverter works fine even if one string has a VMP < 300 volt. The Panel‘s rated voltage ( U mppt ) = 27.2 volt Yes error 19 ( isolation fault ) pops up Yes that’s exactly what I tried to measure, however I measured in the...

Please don’t get me wrong : I understand that a megger is needed if you want to measure the insulation resistance by shortconnecting the positive and negative electrodes of the PV string, and measure the insulation resistance between the shorting point and earth ( the megger applies testing...

@wpns You mentioned that sometimes there may be a short at high applied voltages. Could you please explain a little ? Thx

Ok, I have an additional question for you : Is it safe to measure string’s current while the inverter is running with clamp meter ( measuring current at the inverter’s DC input with clamp meter ) ?

Thanks, well I measured in the night( low voltage ) I have two strings: first string’s VOC 310 volt Second string’s VOC 620 volt I measured voltage to earth and was ~ 0 volts ( for all strings ) while measuring the insulation resistance of the first string gave : Positive to earth 17...

@Sennen Thx for the reply, unfortunately i don't have RSD! all i have is a string inverter and two DC wires coming from roof into the inverter, the panels are on the roof. so you mean it's enough to turn off DC inputs in the inverter ? Dunno but i am a bit afraid of the quite high voltage...

So longer wires means automatically lower ohms resistance ? If we measure insulation resistance we expect higher resistance at the smaller string than the bigger one, right?

Only string 1 is plugged in : voltage 606.1

MPPT tracker range 350-800

No combiner boxes, strings are totally separate

Okay, thanks This confirmation is exactly what i looked for ! However there is still one major issue, the panel and /or its wiring has an earth fault so i expect there is current leakage into ground at that point. i've read that one should be very careful before touching /working on such...

@hwy17 well, i believe unless i isolate that panel completely from the rest panels, there is a risk that i would close a high voltage circuit with my grounded feet! perhaps the safest approach here is to isolate the panel completely from the array by unplugging the MC4 at the previous and...