Using an Exo Terra thermostat (600 W) to your reptil heat sources allows you to be able to control the temperature of your solar site in the terrarium with more accuracy. You prevent overheating your terrarium on hot days and it doesn't get too cold during chilly evenings.
Place the thermostat's heating sensor in a suitable location at your heat sources and connect them to the thermostat. The red LED indicator lights up when the unit turns on and this happens when the temperature drops below the desired temperature set on the thermostat.