I solved the noise problem with 3 120 mm silent pcfans
The 12kw deye inverter has an internal fan that Are very noisy .
this fan is starting at about 35 gr.c , to make the inverter silent is to keep it under 35.gr.c
If you got a 3d printer i have uploadet the stl files to thingiverse
https://www.thingiverse.com/thing:6125037