Hooray. Got a ventilation fan installed yesterday for my solar cabinet and powered off the Aux output of the FlexMax60 charge controller. Automatically turns the fan on/off when the battery is over/under 26.7V. It would be better to have a temp sensor trigger, but that would require extra gear and a relay. As summer progresses and it stays warmer longer into the nights, I can lower that voltage setting to have the fan stay on longer and fire back up earlier.