The article regards aspects of PV modules tested with the use of natural sunlight. The analysis of spectral structure of solar energy resources in southern Poland, carried out on the basis of meteorological data originating from SolarLab PW Wrocław and AGH Kraków, Poland [1] was used in the article. It is a continuation of the article: Analysis of solar energy resources in southern Poland for photovoltaic applications [1], describing the method to determine spectral parameters of average photon energy (APE) and useful fraction (UF) with the use of a solar radiation spectrum simulator. This article, however, includes an experimental presentation of their impact on PV conversion of modules with different absorbers. Theory and practice of the measurements were described with the use of spectral parameters such as: UF, APE. Their influence on the efficiency of modules’ photovoltaic conversion with various spectral characteristics of absorbers was presented. The most recent methods described, which characterise the structure of solar energy resources such as annual distributions of APE and UF, have not been commonly used yet in Poland and other countries, even though they most precisely define adjustment of the spectral factor to the selected PV module.

Practical application of UF, in detection of absorber type used in the tested PV module/cell is demonstrated in the final part of the article.

Lasers emitting mid-infrared (MIR) beams have become indispensable for spectroscopy, free space communication or remote security measures. To the one of the most promising families of the lasers suitable for these applications certainly belongs a group of the Quantum Cascade Lasers (QCL). However, among the conditions they must satisfy there is a high enough radiance of the beam they emit. Radiance depends in a complicated way on the laser output power and optical quality of the laser beam. This paper has been devoted to a description and a short analysis of the factors that decide about radiance of so far developed QCLs. Literature concerning both single devices and QCL arrays operating in beam combining systems have been examined and results described. The survey may be useful for estimation of how far the QCLs have come of age.