Repairing My Solar System After a Lightning Strike

[philanthropist]

Hi, I've recently had to replace all of the blocking diodes on 12 - 250 watt solar panels after most were damaged by a lightning strike. Panels are rated to put out 49 volts. After replacement - only 4 panels put out 45v, 5 put out 28-29v, and 3 -15v. I need to know if I can still wire them up in a string like they were and do I use the weakest at furthest end away from inverter. Or do I simply avoid wiring the 15 volters ? I'm clueless what to do next. Your advice is much valued.

[Mike90250]

Call your insurance company. While the panels appear to work NOW, I'll bet that in 6 months they will be mostly dead.

Did you have a direct hit on them or a nearby strike ?

[philanthropist]

It was a neaby hit. I called out a solar guy and he said "It's an easy fix problem...just replace the Schottky blocking diodes and problem solved" What he said made sense because prior to replacement the voltage on most/all of them was between 0.2 and 0.8. After changing the diodes I got 45v in 4 panels 28-29 on 5 and 15 in 3.
I noticed that the diodes have to go in one direction with the line facing towards the positive. The ones that I installed in like manner were pumping out 45v out of max 47. The others that were reverse installed were giving me other readings. I thought strange how readings were all in 3 similar categories. ie. 45, 30 and 15. So now i've replace diodes facing correctly. Cannot test now as it is almost midnight. Tomorrow ay midday I'll see if I get the correct readings.
Thanks for replying, Mike. I'll call Insurance anyway...

[zed]

...

[Mike90250]

Are you able to test the diodes before removing them, are they shorted or open ? PV panels work without diodes. The only diodes in panels are BYPASS diodes that allow some of the panel to work if a small part is shaded.

Blocking diodes are for preventing batteries from backfeeding unlit panels at night, depleting the batteries. Most charge controllers provide this function now.

The PV Cell is a P-N Junction, much like a bypass or blocking diode is a P-N junction device. If a near strike fried the diodes, you can bet the panels sustained some damage too, it just has not shown up yet. Sorry.