I have an off-grid solar panel set up ready and it works really well. My solar PWM charge controller of the back side aluminum heat sink is too hot to touch when its during sunlight. I was thinking about using a brushless fan for cooling the heat sink. I checked the voltage of the panel and its about 19.4v when peak. So it should be good to use a 24v fan since I don't need full speed and that the adequate fan will cool the heatsink during the daytime. I did not use 24 hours running the fan since the heatsink is not hot during night so I don't think I need battery backup.
The question is that if during dusk/evening then will the undervolted fan might struggle got damaged? I know that regular fan/motors will damage but will a brushless fan damage since they have electronics and may have a cut off or something? The brushless fan I'm using a regular Chinese 60mm brushless fan used for computer chassis.
Edit: Will a diagram like this work?
