Our Spektron 485mb digital irradiation sensor are build out of a monocrystalline solar cell connected to a shunt. Due to the low resistance of the shunt, the cell operates next to short circuit. The temperature coefficient of the short-circuit current creates a small error. Therefore all of our silicon sensors with the extension „TC“ have an active temperature compensation, which reduces this error by factor 20. The compensation is realized by using a specific temperature sensor laminated to the rear side of the solar cell. The measuring signals of short-circuit current of the cell and the resistance value of the temperature sensor are measured by a microcontroller. The calculated values of irradiance and temperature are given onto a RS485 port with customer specification protocol. The electronic circuit is optimised for low power consumption. All sensors are calibrated in simulated sunlight against a reference cell of the same type. The reference cell is periodically calibrated against a reference cell calibrated by Fraunhofer ISE, Freiburg.