A new topology for a buck-boost switching regulator is provided herein. The system, method, and apparatus can include a sensor that is configured to provide a notification signal when a surface of a screen panel has worn to a threshold level. The backup power supply serves as a voltage reference to set the power supply switchover level only when the output voltage of the primary power supply is lower than the output voltage of the backup power supply. The outer panels and the strip are placed directly onto the wound flexible elongate element. Alternatively, thermal solar screens are assembled by connecting a pre-formed screen-frame assembly and a pair of pre-formed end members.