How can I repair a solar panel (replace the blocking diodes) without access to the exact same components?
I have a 100 watt 20volt semi-flexible solar panel marked PV-XC502 on the junction box, opening it up I can see two components each marked 20S0045 in what appears to be a T0-252 package (or similar). It has a symbol which appears to be a pair of inwards pointing diodes. I assume that each component is either a single blocking diode OR (going by the picture on the case) a pair of blocking diodes.
The problem is that googling the chip markings produces no useful results. Re-soldering a couple of diodes should be within my skill level, but I’m not 100% sure what the components actually are (diodes or pairs of diodes) and without that information I can’t even look to replace with something similar.
The solar panel does still produce a reduced output, so I’m reluctant to start on a destructive investigation, the junction boxes is full of copious amounts of solder which makes it very hard to work out what’s connected to what.
How can I either a) find out exactly what the component is supposed to be, OR b) work out exactly how the existing cells are wired up do I can try to source some similar components.
I have tried to photo the item, but it’s so small and dirty and the markings are so faint it’s impossible to produce a usable image.
UPDATE – When I google I get both the items that @Bimpelrekkie links to. But these don't appear (to me) to be the same component. The tag 20S0045 doesn't appear in either of the linked datasheets, so how's is it possible to be confident it's the same device? or even a like for like replacement? Aren't these two links just random google guesses?
Best Answer
The problem is that googling the chip markings produces no useful results
Not sure how your Google foo is then because, when I search "20S0045" I get:
DSS 25-0045A http://www.farnell.com/datasheets/123607.pdf
but that uses a different package (2 pins and a tab)
and I get:
SM74611 http://www.ti.com/lit/ds/symlink/sm74611.pdf
which is in a TO-263 which looks similar to a TO-252.
The "killer feature" of this SM74611 is that it has a forward voltage drop of only 26 mV at 8 A (I am curious how they can achieve that!).
These SM74611 can easily be ordered at Digikey or Mouser.
Since these SM74611 are much "better" (much lower forward voltage drop) than regular Schottky diodes I would really replace the faulty ones with the same model. Using a more "normal" diode will results in more voltage drop, resulting in more heat and a consequently reduces lifespan. In short: normal diodes will not last very long!