Dear Learned colleagues,
my dad's 10 years old solar PV array has started playing up. It comprises 14 panels of 250Wp each fed in two strings to a Solis (?) So;arRiver 3600 inverter.
Here's the chronology:
30th December 2023: Noticed no output for the previous 2 days. Weather had been awful, raining constantly for 4 days!
No time to investigate so a Microsoft reset was instigated (OFF-ON at both DC and AC isolators).
System booted up, producing 350W.....still she-ite weather.
1st January 2024: Back to 'isolation failure'. Cover off isolator, noticed both strings paralleled into single DC input to inverter (that's part of the inverter design, not a mod)
I isolated one of the strings, a 50:50 guess, and now it's reliably working, albeit producing less than it should; never mind, it's January.
What this indicates (I think) is that one of the strings has an insulation fault to earth, and probably because of the constant battering from the elements. In spring I aim to go on the roof to investigate and cure the fault, and this is where you experienced chaps come in:
1. Is it OK to use a Megger on the string leads (at night!) to determine/confirm an insulation breakdown? 500V? 1000V?
2. How does one disconnect an MC4 connector? Special tool or just the right technique?
3. Is the best method to half-split the string by taking out the middle panel, then re-test with the Megger?
Luckily it's a bungalow!
Kind regards, MM
my dad's 10 years old solar PV array has started playing up. It comprises 14 panels of 250Wp each fed in two strings to a Solis (?) So;arRiver 3600 inverter.
Here's the chronology:
30th December 2023: Noticed no output for the previous 2 days. Weather had been awful, raining constantly for 4 days!
No time to investigate so a Microsoft reset was instigated (OFF-ON at both DC and AC isolators).
System booted up, producing 350W.....still she-ite weather.
1st January 2024: Back to 'isolation failure'. Cover off isolator, noticed both strings paralleled into single DC input to inverter (that's part of the inverter design, not a mod)
I isolated one of the strings, a 50:50 guess, and now it's reliably working, albeit producing less than it should; never mind, it's January.
What this indicates (I think) is that one of the strings has an insulation fault to earth, and probably because of the constant battering from the elements. In spring I aim to go on the roof to investigate and cure the fault, and this is where you experienced chaps come in:
1. Is it OK to use a Megger on the string leads (at night!) to determine/confirm an insulation breakdown? 500V? 1000V?
2. How does one disconnect an MC4 connector? Special tool or just the right technique?
3. Is the best method to half-split the string by taking out the middle panel, then re-test with the Megger?
Luckily it's a bungalow!
Kind regards, MM