Photovoltaic panels are exposed to extreme environmental factors (UV, drought, temperature fluctuations), which complicates but does not prevent the growth of microorganisms (fungi, yeasts, bacteria and archaea) and the formation of biofilms. This biological growth, together with the deposition of surface particles, reduces the efficiency of the panels, as it hinders the access of light to the photovoltaic cells. In this paper, we studied 28 isolates isolated from the surfaces of photovoltaic panels. We cultivated them on different media (MEA, OA, PDA, PNA and DG-18) and at different temperatures (4 ‒ 40 °C). By aligning the nucleotide sequences of the ITS region with the MEGA7 program, constructing the phylogenetic tree and using the BLAST program, and phenotypic characteristics, we classified the isolates among Ascomycota, into the classes Arthoniomycetes, Eurotiomycetes and Dothiodeomycetes, and genera Phaeococcomyces, Neophaeococcomyces, Knufia, Trichomerium, Coniosporium, Dothiora, Constantinomyces, Neocatenulostroma, Capnobotryella, Elasticomyces, Neocatenulostroma, Neospissiomyces, among which eleven species are still unnamed. The relationship among isolates was also determined using the MALDI-TOF MS method. Based on microscopic images, we found that the key features of the studied taxa that affect the growth and survival of the extreme environment of photovoltaic panels are melanization (protects against UV radiation, acts as an antioxidant and participates in thermoregulation), meristematic/microcolonial growth (better temperature tolerance, reduced desiccation), EPS sheaths (facilitated adhesion, a protective network enabling survival during temperature and water fluctuations), specific reproductive structures (endoconidia and arthroconidia reduce the energy input of reproduction). MALDI-TOF MS analysis proved to be a complement to the analysis of the ITS region, as it confirmed the specificity of the protein profile for distinguishing between species in cases where the ITS region was too conserved to distinguish between species.
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