Here you can see several features of how these solar arrays are mounted on Kvant. In the real Mir, these panels were added on some years after the core was launched, and the base quad-trusses on Kvant were attached via cosmonauts doing EVAs. On the kit, that four-footed truss is simply super-glued to the side of Kvant with no sort of anchor. So I added an internal aluminum tube to anchor the removable panels, since the truss alone would be too weak.