mecer axpert 11KW inverter noise like a meat chopper

Hi, I recently installed a 11KW mecer axpert inverter, however the noise level of the fans are like a meat chopper, especially when the PV is on during the day. The noise is pretty normal at night when it’s on line-mode and/or battery mode without PV usage (night time as well).

Any idea how to dampen the noise? I tried reducing my battery charging current to 20A and the maximum discharge current to 30A with no success. I even tried changing the output source settings from sol-utility-bat to utility-sol-bat (even though the latter would nullify the reason for my installation of solar panels in the first place), once again with no success. Is there any way to reduce the noise?  It’s over the 80DB mark when the fans are spinning, which happens quite a lot, especially when the sun is out.