Method and device for monitoring sun irradiance

The various aspects relate to alignment of a device for determining incident solar irradiation. The device may be rotated over one or two angles - preferably azimuth and/or zenith. By monitoring an output signal of a narrow aperture radiometer to one or two of these angles, a maximum or minimum may be found. In any case, a peak or a valley will usually be detected in the signal and the solar position is determined as the peak or the valley. Hence, the narrow aperture radiometer may be used for alignment of the device, as well as for performing actual measurements. The device may also be equipped with a wide aperture radiometer that may be covered or uncovered for direct solar irradiation. In such device, the detector of the wide aperture radiometer may be calibrated to the detector of the narrow aperture radiometer.