DEXT connection to Solar Panels

[Allen Tindall]

The following is an answer you gave me which relates to my existing installation using an Optocoupler and three DSSR 20's to connect to my solar panels.  I am currently working on the diagram to replace the Optocouplers with a DEXT.  In another thread you stated to use the DEXT 4S connections for the Solar panels.  Can you provide the best way to connect DEXT 4S to the DSSR 20 RCN and RCP?  

Allen,

The diagram looks OK except for the DSSR20 you need to disconnect the RCP you will not use that at all just the RCN should be connected in your diagram.

The RCP inside the DSSR20 will go to PV panels positive trough some resistors so it is not doing anything other than powering the RCN but since you already apply +12V that is sufficient and you do not want to involve the RCP that can be higher voltage so that RCP connection remains unused.

[Dacian Todea (electrodacus)]

You have older version of DSSR20 the v02c ?  That is based on the fact that you mention RCn and RCp

In that case all you do is connect one of the terminals of DEXT 4S to RCp and the other one to RCn. 

The DEXT can handle up to 400Vdc (not a typo 400V) so it is no problem to handle the RCp as supply no matter what your panel open circuit voltage is.    When you used those Optocouplers those were only rated at 30V and could be damaged by the RCp thus the reason I recommended to use +12V and a resistor with those.

You can of course continue to use the +12V and resistor instead of RCp but is not needed with DEXT so you can simply connect 4S to RCp and RCn.

[Allen Tindall]

Thank you.  That makes connections simple.  I have DSSR20 version V03d if that makes any difference.

[Allen Tindall]

Please provide the part numbers for the 4 connection and 3 connection plugs that come with the DEXT.  I need purchase a pair of 2 connection plugs so I can connect ADC 2 and ADC3 after the SBMS is powered on.  

[Dacian Todea (electrodacus)]

Allen,

Unfortunately a pair of two connection plugs will not properly fit in the 4 connection connector. I just tested and if you force them they will get in at a bit of an angle.

Just search for "3.5mm pluggable connector" and you will find versions from many brands but also different variants.

Here is a two connection one with connections on top and screws on the side as I provide with the DEXT  https://www.digikey.ca/en/products/detail/adam-tech/EBKA-02-A/9830661

But there are also variants with connections on the side and screws on top     https://www.digikey.ca/en/products/detail/molex/0395037002/4480319

And there are also spring terminals as the 2x8pin I provide on DEXT but a bit more expensive  https://www.digikey.ca/en/products/detail/phoenix-contact/1952267/2071461

You can test plugin a 3 connection in to a 4 and next to it one pin from another connector to understand the limitation and why they do not fit great.