The Photovoltaic (PV) systems and the semiconductor PV technologies are heavily impacted by shading conditions; total or partial. Nearby residential buildings, commercial buildings, objects, etc. are likely to cause shade on the PV installations.  This study focuses on the evaluation of the effect of shading on thin-film PV modules, which were analyzed under two categories: single thin-film module and a string of modules installed at the University of Gävle, Sweden. The measurement was made by using METREL MI 3109 Euro test instrument. The study intends to help researchers to analyze the variation in the output performance parameters and behavior considering different types of shading on the thin-film modules. Experiments have been performed by creating full and partial shading (uniform and nonuniform) by using plastic foil, opaque board, wooden pole, and tape to emulate different types of natural shading conditions.  The findings show a loss in power due to shading. In the single thin-film modules, which do not have any diode between the cells; reverse breakdown, power dissipation and generation of hot spots are caused by the cells which are partially shaded.  In the string of modules installed at the University of Gävle, Sweden; under partial shading conditions the diodes are activated below certain voltage when current is high, leading to current bypass and therefore prevents the module from the damage caused by high heat generation. Under the condition of extremely low shading by a wooden pole, the diodes were not activated; however reverse breakdown was observed similar to the case of partial shading in single thin-film modules.

Différentes approches ont été utilisées pour évaluer les effets de deux formes de nanoparticules de carbone (NPC), nanotubes et graphène, afin de comprendre les mécanismes de la réponse générée par la diatomée benthique d'eau douce Nitzschia palea. Les effets à l'échelle de la communauté ont démontré un impact temporaire sur la croissance du biofilm et une accumulation des NPC dans la matrice extracellulaire. L'application d'une étude transcriptomique a mis en évidence l'importance de l'interaction physique, à l'origine d'altération du frustule, dans la mise en place de cette réponse extracellulaire se traduisant par une surproduction des substances exo-polymériques (EPS). Cette approche a également révélé l'impact des NPC sur l'activité photosynthétique des diatomées et une modification du métabolisme énergétique, suggérant une allocation énergétique en faveur de la production d'EPS. L'étude du protéome extracellulaire a permis d'avoir un premier aperçu de la composition de la matrice extracellulaire, principalement constituée de protéines à caractère hydrophobe. Lors de l'exposition aux NPC, les diatomées semblent produire un système adhésif complexe permettant de renforcer la matrice extracellulaire et d'augmenter la stabilité du biofilm tout en piégeant les NPC. L'exposition des diatomées face au deux formes de NPC induit une réponse présentant une forte similitude notamment pour les plus fortes concentrations testées. / Different approaches were used to assess the effect of two forms of carbon-based nanoparticles (CNP) nanotubes and graphene, in order to determine the mechanism of the response generated by the benthic freshwater diatom Nitzschia palea. The effect at the cellular community scale demonstrated a temporary impact on biofilm growth and an accumulation of NPC in the extracellular matrix. The use of transcriptomic study evidenced the role of the physic interaction, causing alteration of the frustule, in the extracellular response leading to an overexcretion of exopolymeric substances (EPS). This approach also revealed the impact of NPC on the photosynthetic activity of diatoms and a modification of the energetic metabolism suggesting an energetic allocation for the EPS production. The study of the extracellular proteome allowed to have a first insight of the extracellular matrix composition, in majority composed of hydrophobic-like proteins. In NPC exposure, diatoms seemed to produce an adhesive system allowing to strengthen the extracellular matrix and increase the biofilm stability while trapping NPC. The exposition of diatoms to the two NPC forms induce a response greatly similar for the highest tested concentration.

Water quality in streams around the world continues to be degraded by a series of human activities that feed pollutants into the vulnerable stream ecosystem via surface and subsurface runoff. This continues to accelerate global biodiversity and habitat losses within the stream environments and across entire watersheds with net adverse effects on public health and the ability of communities and ecosystems to adapt or become resilient to the prevalent impacts of climate change. One commonly used approach for protecting stream water from pollution is the use of vegetated riparian buffer zones to mitigate pollutants in surface and subsurface runoff prior to runoff entry into the stream channel. The optimal success of this approach requires land and water resource managers to understand the mechanisms by which riparian buffer zones function and the full range of factors that influence the effectiveness of riparian buffer vegetation in abating stream water pollution. Despite this need, resource managers in different geographical locations around the world still struggle to understand the linkages between riparian vegetation and stream chemical quality. This literature review therefore sought to synthesize findings from various scientific articles on the ways in which the major attributes of riparian vegetation [type, age, width, restoration and shading effect] influence the effectiveness of riparian vegetation in protecting the chemical quality of water in streams. This was aimed at generating conclusions and perspectives that could improve academic knowledge and natural resource managers’ understanding of the intricate linkage between riparian vegetation and changes in water chemistry. The study finds that the factors of riparian vegetation type, age, width, restoration and shading effects require due consideration in the development of riparian buffer zone and stream water chemical quality management interventions. I find that these factors require a high degree of integration, triangulation and context-specificity to achieve the objectives of riparian management intervention. I further find that stream water quality decision-making processes need to combine riparian vegetation-based approaches with other measures for mitigating and containing the spillage of pollutants at the source. / <p>Presentation was conducted via Skype</p>