Victron panel junction box - extra bypass diode?

[bdl]

Here's a picture of the junction box on the back of a Victron SPP041751200 175W panel:


Notice the three diodes - yet only two panel sections (three tabs). The panel physically is an arrangement of 4 x 9; electrically connected in 2 banks of 18 cells each.

I'm wondering why they've installed two diodes across one of the panel halves?

 

[gnubie]

Is that the original junction box? Terrible soldering, and even more to the point, soldering! Out of the panel's I've taken the back box apart on, including Victron on a boat at the local harbour, they have been clamp connections not soldered.

 

[bdl]

Yes, original. I agree re. quality of the soldering; the joints appear solid but they're not pretty.

 

[gnubie]

It's obviously a box intended for more bypass points in the panel.

Soldered instead of clamped, strips not fed through reliefs, bad soldering job, and wrong connector box anyway. All round very strange. TBH I'd even be seriously wondering if it's a genuine Victron product. Certainly not up to the standard that I'm used to seeing when peering inside Victron products. The only time I've seen anything as bad as that has been on my own temporary fix to a broken panel where I didn't have an iron up to the task.

 

[bdl]

FWIW the only reason I can think of as to why Victron did this is basically laziness: this junction box is obviously designed for up to three strings and probably come with diodes preinstalled for three strings (three diodes), and Victron just slapped it on and wired it in for the two strings. It'll "work", but will have a higher voltage drop and a few watts of wasted power when that half of the panel needs to be bypassed.

I'll probably replace the superfluous diode with a link, and clean up the soldering whilst I'm there...