Solar Panel failure

[ProDave]

My ground mounted PV is now about 6 years old.  I read my meters once a week to record usage and generation etc.  When doing that on Friday I noticed the weeks PV generation was tiny (even for the time of year) and the inverter was showing an error.

 

Yesterday was time to investigate.  The inverter was tripping on excess leakage current, and powering down and re starting it did the same every time.  Shut down and disconnected the DC from the inverter and sure enough one string was showing a leakage to earth of just under 1 megohm.

 

Next step was go and disconnect the panels in the solar shed.  Thankfully the interconnecting cables now showed very good IR.  That was a relief as I had feared an issue in the 100ft long buried DC cables.

 

Next go round checking panels one at a time. I soon found the rogue panel that on it's own shows this high leakage.  For the time being I have reinstated things with this one panel bypassed so it is working again but one string is 1 panel short.

 

The repair plan is this.  I had 2 spare panels that are one on each end of my shed vertically connected to a cheap Chinese inverter to try and give a little extra early morning and late afternoon power.  I will take one of those to swap with the faulty panel on the main array.  Thankfully by happy accident is is the easiest panel to access on the main array that has failed.

 

I will then investigate what has gone wrong with this panel.  Though I suspect used singly on the cheap inverter it may just work, as I doubt that cheap inverter has all the checks that the proper one has.

 

This is the first time I have come across and insulation resistance issue on a PV panel before.  They are after all designed for outdoor use but clearly damp has got in somewhere on this particular panel.

 

I am very thankful that this is something I can do myself, that I have a spare, and being ground mount I don't need the complication of scaffold (though I have that if it were needed)

[Kelvin]

It’s another reason I am ground mounting mine too. 

[SteamyTea]

8 hours ago, ProDave said:

This is the first time I have come across and insulation resistance issue on a PV panel before. 

Has the back been damaged, they seem to be covered with the best Blue Peter sticky back plastic.

[Marvin]

I have found poor soldering of the cables to the panels before...