title: Microbial colonization affects the efficiency of photovoltaic panels in a tropical environment.
abstract: Sub-aerial biofilm (SAB) development on solar panels was studied in São Paulo. After 6, 12 and 18 months' exposure, photovoltaic panels were covered by increasing proportions of organic matter (42%, 53% and 58%, respectively). Fungi were an important component of these biofilms; very few phototrophs were found. Major microorganisms detected were melanised meristematic ascomycetes and pigmented bacterial genera Arthrobacter and Tetracoccus. While diverse algae, cyanobacteria and bacteria were identified in biofilms at 6 and 12 months, diversity at a later stage was reduced to that typical for SAB: the only fungal group detected in 18 month biofilm was the meristematic Dothideomycetes and the only phototrophs Ulothrix and Chlorella. Photovoltaic modules showed significant power reductions after 6, 12 (both 7%) and 18 (11%) months. The lack of difference in power reduction between 6 and 12 months reflects the dual nature of soiling, which can result from the deposition of particulates as well as from SAB fouling. Although 12-month old SAB demonstrated an almost 10-fold increase in fungal colonization and a higher organic content, the larger non-microbial particles (above 10 μm), which were important for efficiency reduction of lightly-biofilmed panels, were removed by high rainfall just before the 12-month sampling.
authors.affiliation: Polytechnic School of University of São Paulo, Construction Engineering Department, Av. Prof. Almeida Prado, trav. 2, n.83, Edif. de Eng. Civil, Cid. Universitária, São Paulo, SP CEP 05508-900, Brazil. Electronic address: shirakaw@usp.br.
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Shirakawa
authors.affiliation: Institute of Energy and Environment of the University of São Paulo - IEE/USP, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Zilles
authors.affiliation: Institute of Energy and Environment of the University of São Paulo - IEE/USP, Brazil.
authors.forename: Andre
authors.initials: A
authors.lastname: Mocelin
authors.affiliation: Polytechnic School of University of São Paulo, Construction Engineering Department, Av. Prof. Almeida Prado, trav. 2, n.83, Edif. de Eng. Civil, Cid. Universitária, São Paulo, SP CEP 05508-900, Brazil; University of Oklahoma, Dept. of Microbiology and Plant Biology, USA.
authors.forename: Christine C
authors.initials: CC
authors.lastname: Gaylarde
authors.affiliation: Federal Institute for Materials Research and Testing (BAM), Department 4 "Materials & Environment", Germany; Freie Universität Berlin, Department of Biology, Chemistry and Pharmacy & Department of Earth Sciences, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Gorbushina
authors.affiliation: Federal Institute for Materials Research and Testing (BAM), Department 4 "Materials & Environment", Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Heidrich
authors.affiliation: Laboratory of Medical Mycology (LIM-53), Hospital das Clínicas da FMUSP e Instituto de Medicina Tropical, University of São Paulo, SP, Brazil.
authors.forename: Mauro C
authors.initials: MC
authors.lastname: Giudice
authors.affiliation: Laboratory of Medical Mycology (LIM-53), Hospital das Clínicas da FMUSP e Instituto de Medicina Tropical, University of São Paulo, SP, Brazil.
authors.forename: Gilda M B
authors.initials: GM
authors.lastname: Del Negro
authors.affiliation: Polytechnic School of University of São Paulo, Construction Engineering Department, Av. Prof. Almeida Prado, trav. 2, n.83, Edif. de Eng. Civil, Cid. Universitária, São Paulo, SP CEP 05508-900, Brazil.
authors.forename: Vanderley M
authors.initials: VM
authors.lastname: John
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D001938:Brazil; D000458:Cyanobacteria / Q000254:growth & development*; D004783:Environmental Microbiology; D006801:Humans; D012993:Solar Energy; D014329:Tropical Climate
keywords: Energy production; Fouling; Fungi; Phototrophs; Solar panels; Sub-aerial biofilms