My 315 watt 24vdc panels normally output 39vdc to the mppt charge controller this is the way that amperage is created in the panel through voltage amps convert to volts in dc without a load to consume them you need to use a charge controller between the panels and fans to limit the voltage into the fan pwm controller will work just fine as.
Solar panel voltage regulator 24v.
In order to regulate the voltage from the solar panel normally a voltage regulator circuit is used in between the solar panel output and the battery input.
Epever 80a mppt solar charge controller 12v 24v 36v 48v dc automatically identifying system voltage max pv 150v solar panel regulator tracer 8415 an 5 0 out of 5 stars 10 335 59 335.
Mohoo solar charge controller 30a solar charger controller 12v 24v solar panel intelligent regulator with dual usb port and pwm lcd display upgraded 4 1 out of 5 stars 251 15 99 15.