LIghtning hit!

[solarix]

Well, just examined a 3 year old system and discovered out of 3 strings of 11 panels, a damaged panel in each string. Homeowner admits they had a lightning strike. Two panels are showing a Voc of just 25V (instead of 35V like the rest) and one panel is showing good voltage but only 2.5Asc. None of the fuses in the DC combiner were affected and the (good 'ol) SMA inverter survived just fine. The two strings with low voltage were putting out zero amps due to being tied to the one string with higher voltage.

Question is: Do I need to pull the whole array apart and individually test each panel to make sure there is no other damage? Will have to replace these 3 panels of course, but could there be more?

[DaveDE2]

If it were me, I'd start by bypassing each of the one bad panel in each string. Then measure Voc and Isc of each string and compare. They should be nearly equal. If they are, then the rest of the panels are good. This assumes all the panels are uniformly illuminated. While you're at it, you could connect each bypassed string to the inverter at the combiner box with the other two disconnected and monitor the AC power output and compare.

[DaveDE2]

... by the way, I'd be willing to bet that the two panels with 25Voc have smoked (shorted) diodes in the little box where the wires enter the panel. These are 50 cent parts that could easily be replaced and make those panels good again but I get it, that repair is unlikely to happen. The panel with low Isc probably has a damaged cell.