so,the whirlybird isnt propelled by the rising hot air,but the gentle breeze outside,the bonus is the wind action draws out the hot attic air.a small driveshaft would easily drive a dynamo in a breeze.
aiming panels-incorporate an air bag of sorts,black in color,as sun hits it use the expansion to change position.
or if it can be balanced so it turns easily,a clock mechanism,like the ones used on a timer.my household water filter has a clock of sorts,runs on 12 volts,it has a fair amount of torque to activate the rinse cycle valve.
its a filtersoft timer.