The radiation sensor GBS-F is used to measure the solar radiation [W/m²]. The sensor simplifies system startup or makes possible more precise „switching up“ in the priority consumers with multi-circuit solar systems. The sensor is supplied from a small solar panel. A PT1000 collector sensor can be connected to the GBS-F, the measurement value of which is likewise transmitted to the receiver. The GBS-F+KPT is delivered with the PT1000 collector sensor.