My off grid home uses powerbright inverters and as much as I love these units, the internal cooling fans fail pretty fast.
Here is how I installed an external temperature controller and fan for my inverter.
Step 1: Controller.
This controller runs off 24vdc and is fully programmable. The Centre led shows the real time temperature. The left led is turn on temperature. The right is turn off.
Step 2: Fan.
I used a 24vdc brushless fan stuck externally to vent the inverter.
Step 3: Sensor.
The thermal probe I glued onto the case.
Step 4: Wiring.
I used the onboard relay to switch the 24vdc supply to the fan. The negatives for fan and controller are the same. Crimp lugs I used to provide supply from the inverter's power lugs.
Step 5: Completion!
At a turn on of 38C and off 33C, the new fan controller is operational and hopefully should give long service life.