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Updated: Apr 14, 2026
In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells
Published on: October 3, 2018
Microbial colonization affects the efficiency of photovoltaic panels in a tropical environment
Marcia A Shirakawa1, Roberto Zilles2, Andre Mocelin2
1Polytechnic 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.
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.
Insights
Sub-aerial biofilms (SAB) on solar panels significantly reduce power output, with fungi and bacteria dominating the microbial community. Power loss increased over 18 months due to organic matter accumulation, despite rainfall washing away larger particles.
Area of Science:
- Environmental Science
- Microbiology
- Materials Science
Background:
- Sub-aerial biofilms (SAB) are increasingly recognized as a significant factor affecting solar panel performance.
- Understanding microbial community dynamics and their impact on photovoltaic (PV) modules is crucial for optimizing energy production.
Purpose of the Study:
- To investigate the development of SAB on solar panels in São Paulo over 18 months.
- To analyze the microbial composition and organic matter accumulation within these biofilms.
- To correlate biofilm growth with photovoltaic module power reduction.
Main Methods:
- Exposure of PV panels for 6, 12, and 18 months in São Paulo.
- Quantification of organic matter and microbial colonization.
- Identification of dominant microbial genera and groups using microscopy and potentially sequencing.
- Measurement of PV module power output.
Main Results:
- Organic matter content in SAB increased from 42% at 6 months to 58% at 18 months.
- Fungi, particularly melanised meristematic ascomycetes, and bacteria (Arthrobacter, Tetracoccus) were dominant.
- Photovoltaic module power reduction was 7% at 6 and 12 months, and 11% at 18 months.
- Biofilm diversity decreased over time, with specific fungal and phototrophic groups identified at later stages.
Conclusions:
- SAB significantly impacts solar panel efficiency, with increasing power loss over time.
- The composition of SAB shifts towards specialized microbial communities with prolonged exposure.
- Both microbial fouling and particulate soiling contribute to power reduction, with rainfall influencing the latter.
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