Solar Panel Holder for dual monocrystalin solar panels:
https://www.banggood.com/5V-250MA-1_25W-Mini-Solar-Panel-Photovoltaic-Panel-p-987900.html?cur_warehouse=CN
Twice printed results in a foldable dual panel holder.
Can be fixed on tube holder with 2 distance tubes usin a M6 100mm long screw.
The serial connection of the 2 panels delivers up to 10V and in the example shown drives a 12V Arctic F8 Silent fan.
https://www.arctic.ac/eu_en/f8-silent.html
Another example would be to connect the solar panels parallel to load batteries with 5V output.

Flyingbear

Doesn't Matter

Yes

0.15

90%

Clean mechanically the supports to connect 2 same panel holders together.

First i designed the holders in the OpenSCAD then added the supports within the Meshmixer, printed several times until all problems habe been fixed.
The Tube Holder was designe also first in OpenSCAD and improved in ScetchUp.
The panels have been connected serially to drive the Arctic F8 silent fan and tested behind the windows.