Bypass & pass thru diodes

[GP28]

Was wondering on use of these; Bypass for series and blocking for parallel,,, ball park right?? Blocking are like most MPPT's it seems, voltage can vary (5-150) for example only,, but current is more critical? Lets say have 2 panels rated same 200w for 12V system (example only) and each one had a blocking diode at + side for shading purposes and to ensure it gets "taken out" of system as long as its shaded? Is that to keep the other panel from sending stray power back through it?
Am looking at a schematic/drawing of a system that has it installed and trying to get it in layman terms without all the formulas and high depth engineering terms..

It would seem that the bypass diodes would be more critical for correct voltage/amperage ratings to make sure power isn't able to take path of least resistance and just bypass panel when not needed to..

 

[upnorthandpersonal]

Blocking diodes exist in an MC4 package like this:
https://thargo.com/product/mc4-blocking-diode-adapter-rated-20a/

Get one that has a higher forward current than your maximum current per string, and a reverse voltage as high as possible. Schottky diodes are usually better, but not sure how common they are in this form factor.

Bypass diodes are already built in in modern panels, but if not, using the same type as the ones used for blocking is fine.

 

[GP28]

Yes, I got two from Amazon @ 15amps, was highest amperage I could find that wouldn't take 2 months to get here. I think this place was one that would take a month to get here. I ordered 2 @ 15 amps, which is hairs wisker from my max current will be parallel. Will try these wen get it installed and look to something will probably have to put together and make with higher current rating..

I don't believe there is a difference between blocking or bypass, its just the placement and used purpose of them.. I was really surprised that there were really none in the MC4 package with higher ratings, but never studied much on diodes and guess they are mostly for voltage apps??

 

[upnorthandpersonal]

Reason you don't find any larger ones just like that is that there is almost no demand for them. Usually people using them have small arrays, and they are strictly speaking not even necessary to build a working system. Larger arrays use different systems in combiner boxes and different blocking diodes, like in this video:

Or something like this:

 

[svetz]

If you like bypass diodes (the ones in your JBOX anyway), you'll like the Maxim Chip!

 

[Rogli]

Blocking diodes exist in an MC4 package like this:
https://thargo.com/product/mc4-blocking-diode-adapter-rated-20a/

Get one that has a higher forward current than your maximum current per string, and a reverse voltage as high as possible. Schottky diodes are usually better, but not sure how common they are in this form factor.

Bypass diodes are already built in in modern panels, but if not, using the same type as the ones used for blocking is fine.

Hello there. You seem to have knowledge about exactly what I am inquiring about. Please see my concern on this thread that I started. Kindly give your opinions.

Placement of bypass diodes

Hello mates. I am new here and have some beginner level experience with solar panels. I have asked this question about bypass diodes placement from some installers but they have no idea about it. Apparently, installers do not place bypass diodes in their installations but I heard that bypass...

diysolarforum.com

 

[upnorthandpersonal]

@Rogli - Seems you had a few replies there - is something still not clear?

 

[Rogli]

Thanks. Yes, please refer to my illustration. Can bypass diodes not be installed outside solar panels? Your picture clearly shows bypass diodes outside the panels meant to shun an entire panel in case of shading.

 

[upnorthandpersonal]

They can, however most solar panels come with those installed already (and technically are 'outside', just in the combiner box at the back of the panel). It's easier to check them/replace when needed. This is especially the case with 'half-cut' panels. Diodes outside the panels are always considered blocking diodes these days and might be part of the connector. They're often left off as well with no issues on typical installations.