The Kaco Irradiance Sensor is used for professional monitoring of your photovoltaic installation. Based on the measured solar radiation the expected energy yield can be determined and compared to the actual yield. The shortcircuit current of a silicon (Si) solar cell is proportional to the solar radiation. The Si sensors use a monocrystal solar cell, which is virtually operated under shortcircuit conditions via a low-impedance resistor. As the positive temperature coefficient of the short-circuit current results in a low results in a low measuring error, Si sensors (abbreviated: "TC") are provided with active temperature compensation so as to to reduce this error by the factor of 20. A special temperature sensor is laminated onto the rear side of the solar cell for this purpose. All sensors have been calibrated under sunlight conditions to a pyranometer.