See what I mean? If you would have snipped the little buggers out, they would not have popped!
I never saw a 12 or 24V with other than 2.
Bypass diodes in standard panels, in standard configurations, have no use in standard 12V or 24V systems,
and are best removed before they cause problems IMHO.
I agree with the rest of your comments, Glen, but I'm a little puzzled by this bit?
If your module has two (or more, I've seen some with 3 or 4 - but they're rare) bypass diodes, what problems do they cause?
They like to fail into a short circuit condition.
The half with the shorted diode just runs in circles. Nothing goes into the battery.
(possibly they very often fail to open, but that would have 0 effect, so nobody would notice?)
Many people would say this is a minor issue, until they are 60' up on a 75 degree roof, doing everything required to find the problem.
Not fun.
Well, it is almost fun to see a $3 HF meter slide down and hit a cement driveway... until you realize it could be you the next time.
In 12V systems, without high voltage input MPPT, I snip the trouble makes out before they cause me trouble.
I have no good idea why your diodes popped.
The only times I recall seeing them blow up like that was in a panel done by a "retailer" (instead of an 'understander'). He could get three 1A diodes cheaper than a 3A diode, so he paralleled 3x1A, and they blew after a few months or a year.
<tangent> He sold a lot of panels, he could not fix them, so going cheap meant the customer had to pay me.
Whatever money they saved on discount panels from a discount retailer was used up on my fuel cost alone, plus they had crappy parts, crappy panels and a crappy controller.
A better system, with better parts, would have been MUCH less expensive if they bought it from me in the first place.
Back to your situation, is there a chance the diodes went over Vr with MPPT or something?
Most factory installed bypass diodes I see are 1KVr, some/many 600Vr, but never less than 600Vr. Most are rated at >2~3x Isc.
At the moment I can't imagine how avalanche would have any effect... let alone for a duration effecting dt... but it is 3:00AM here... and I smell like pepperoni.
Is more than minute avalanche in bypass diodes even theoretically possible in standard systems?
I don't think it is, but...
G-