This report is number two in a serie of two reports dealing with unaccuracy and errors in optical radiation measurements. The first report was about laser radiation measurements. In this second report ultraviolet spectral and spectrally integrated measurements of irradiance is analyzed. Measurements on solar lamps are especially considered. For this the spectral region of 200-400 nm is of most interest. The biologically weighted irradiance in the UVB and UVC-regions is examined according to the rules in the Swedish SSI FS 1982:1. Here is given a short summary of the most important sources of errors and the estimated size of those errors in both the measured spectral irradiance values and integrated UVA-, UVB- and UVC-irradiances. Practical examples of measurements on solar lamps are included in the report. Both reports are sponsored by the Swedish National Institute of Radiation Protection in the aim of better understanding the measurements problems at the testing centre for laser and at the testing center for solar lamps.