Hi all, Hope you are well.

I have 4x strings of 16 panels in series, all of the issues arose after a heavy storm with lightning.

String 1 - negative fuse blown

String 2 - Positive fuse blown

String 3 - Negative fuse blown

all these fuses etc have been replaced.

Issues

( All the strings have been switched off and testing has been done per string )

String 1 - At the breaker i am only reading +/- 60v, could this be that one of the panels has been damaged?

String 2 - When the breaker is off i read the correct voltage that is 770v, when i put this breaker as well as the pv switch on the voltage drops to zero, could this be a damaged mc4?

String 3 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

String 4 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

For additional context Strings 1+2 are usually on PV1 and Strings 3+4 are on PV2. When testing each string with the inverter i turned off the others.

Any help would be much appreciated, Thank you.

1 hour ago, Mattyboy said:

Hi all, Hope you are well.

I have 4x strings of 16 panels in series, all of the issues arose after a heavy storm with lightning.

String 1 - negative fuse blown

String 2 - Positive fuse blown

String 3 - Negative fuse blown

all these fuses etc have been replaced.

Issues

( All the strings have been switched off and testing has been done per string )

String 1 - At the breaker i am only reading +/- 60v, could this be that one of the panels has been damaged?

String 2 - When the breaker is off i read the correct voltage that is 770v, when i put this breaker as well as the pv switch on the voltage drops to zero, could this be a damaged mc4?

String 3 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

String 4 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

For additional context Strings 1+2 are usually on PV1 and Strings 3+4 are on PV2. When testing each string with the inverter i turned off the others.

Any help would be much appreciated, Thank you.

Hi, you need to give some more info ie:

Inverter (50Kw Deye) Model, panel wattage etc, etc

44 minutes ago, Demo said:

Hi, you need to give some more info ie:

Inverter (50Kw Deye) Model, panel wattage etc, etc

My Apologies,

Deye 50kW hv

Longi 575w

Have you checked the surge arrestors? Not so long ago I had a PV string that wouldn't work after an electrician had added earthing. He checked connections, checked fuses, got frustrated, then we noticed that one of the surge arrestors had given itself up (red flag was showing).

17 hours ago, Mattyboy said:

String 1 - At the breaker i am only reading +/- 60v, could this be that one of the panels has been damaged?

String 2 - When the breaker is off i read the correct voltage that is 770v, when i put this breaker as well as the pv switch on the voltage drops to zero, could this be a damaged mc4?

String 3 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

String 4 - I read the correct voltage of 770v but once the breaker and pv switch is on the inverter goes in F23 fault, could this be a damaged mc4?

String 1 - Could be a panel, I assume none are shaded...

String 2 - could be a poor contact on one or more mc4 connections

String 3 - not sure, but see this thread...

String 4 - same as String 3, presumably an earth fault on those two

I'm spitballing here, I have a smaller Deye, but this is still sealed in its box...

10 hours ago, Kalahari Meerkat said:

String 1 - Could be a panel, I assume none are shaded...

String 2 - could be a poor contact on one or more mc4 connections

String 3 - not sure, but see this thread...

String 4 - same as String 3, presumably an earth fault on those two

I'm spitballing here, I have a smaller Deye, but this is still sealed in its box...

Thanks for your input🙏

So after some fault finding here are the preliminary finds:

String 1 - all panels were damaged, three of which had a voltage reading of 16v and the rest 0v.

String 2 - seems to have been an issue with the mppt which must have been damaged (same mppt that string 1 was on)

String 3 - seems to be an insulation fault, these cables run in an underground pipe so i'm assuming string 1 has damaged these cables as well. it runs fine for a bit then the f24 error seems to arise.

String 4 - for some reason now seems to be working fine but im not convinced.

i will have to run new cable for these strings.

would it be worth installing an earthmat then bonding each structure to each other and then taking a 50mm down to the earthmat to prevent future incidents like this?

bit of a kick in the teeth but it is what it is😅

9 hours ago, Mattyboy said:

So after some fault finding here are the preliminary finds:

String 1 - all panels were damaged, three of which had a voltage reading of 16v and the rest 0v.

String 2 - seems to have been an issue with the mppt which must have been damaged (same mppt that string 1 was on)

String 3 - seems to be an insulation fault, these cables run in an underground pipe so i'm assuming string 1 has damaged these cables as well. it runs fine for a bit then the f24 error seems to arise.

String 4 - for some reason now seems to be working fine but im not convinced.

i will have to run new cable for these strings.

would it be worth installing an earthmat then bonding each structure to each other and then taking a 50mm down to the earthmat to prevent future incidents like this?

bit of a kick in the teeth but it is what it is😅

With the correct size fuses that were blown the cables should not have been damaged easily. The weakest point can be MC4s. Worth checking when the panels are replaced. Check out the bypass diodes in the faulty panels if not done already. It seems strange to have all panels in the same string damaged and not just the weakest link. But yes lightning can have such a high surge that it is possible.

9 hours ago, Mattyboy said:

would it be worth installing an earthmat then bonding each structure to each other and then taking a 50mm down to the earthmat to prevent future incidents like this?

Going overboard on earthing is always considered to be a good thing, if you have the space and possibility, putting up some lightning rods, somewhat away from you panels and not causing shadows, might be worthwhile considering...

Maybe post some photos of the panels setup as it exists, if you can.

I still think the best option to prevent major damage from lightning strikes is to implement a system that has multiple automated disconnect points and is driven by a field mill, which pretty much will show just before a strike that this is about to occur...