Fixing solar panel diodes - Sealed junction box

Older panels had serviceable junction boxes and diodes, but unfortunately modern split-cell panels have fully sealed junction boxes which makes it extremely difficult to replace a blown diode.

I recently came across a system that had 3 panels with blown diodes due to a reverse current after the installer accidentally connected the system with reverse polarity. I’ve never fixed a modern split-cell panel with blown diodes so here is how I did it. Interested to know others’ experience trying to fix blown diodes.

Steps to fix blown diodes:

  1. Remove plastic covers
  2. Use a sharp blade to cut a rectangular area around the diode
  3. Use a very fine flat head screw driver to pick out the filler material
  4. Scrape away as much filler material as possible from around the diode
  5. Heat the solder and remove the faulty diode (test diode first)
  6. Solder the new diode in position - I used new 30A diodes 30SQ030
  7. Fill with fire rated silicon
  8. Replace the plastic cover and cover it with more fire rated silicon

Remember to test the new diode before adding the silicon filler.


Here’s the rest of the photos in order