[en] Short communication

[en] Short communication

[en] This master's thesis addresses the characterization of four different types of Battery technologies; the li-ion, the LiFePO4, the lead crystal and the lead acid. Because these devices are used in electric applications, calculations were made to assess the capacities and energies of the batteries while at different discharges ratios in runs from 5 to 50 hours, which are the most common on the photovoltaic sector. Also, we observed the behavior of the batteries when put through a rise of temperature to measure the fluctuations in the voltage, capacity and energy. Tests were performed at constant power to observe the behavior of the discharge intensity. When making the comparisons of the capacity and the energy, the LiFePO4 battery proved to be the best and better behavior in the tests at constant discharge rates. (Author)

[en] Photovoltaic (PV) systems are almost entirely benign in operation, and potential environmental hazards occur at the production and disposal stages. There are well established methods of monitoring and controlling potential hazards caused by the semiconductor materials used in PV modules such as silicon, copper indium diselenide and cadmium telluride. The main environmental hazards of photovoltaics are connected to the production processes. These processes require an input of energy, and this energy is derived from the standard fuel mix of the nation in which production takes place. The production of PV systems therefore has associated with it, emissions of greenhouse and acidic gases. However, as the new thin film PV technologies come into production, and the scale of production increases, the energy input to PV systems will decrease considerably, with consequent reduction in carbon dioxide emissions, to levels below that of other electricity generating technologies. (Author)

[en] The parameters of an independent photovoltaic system, constructed at the Technical University, Gabrovo are presented. The system is suitable for the meteorological conditions of the town - mean annual temperature 11.2⁰C, 310 sunny hours for July. The town is in the zone with average total annual solar radiation under 1450 kWh/m²

[en] Published in summary form only

[en] An inverted bulk heterojunction organic photovoltaic device based on blend of conjugated polymers and fullerenes derivatives with Cs₂CO₃/PVDF composites as an electron transporting layer. The entire device structure ((Cs₂CO₃/PVDF)/P3HT: PCBM/V₂O₅/Al) has been fabricated using spin coating method and the final metal contact was made using thermal evaporation technique. The mol % of Cs₂CO₃: PVDF ratio and the spin rate of electron transport and P3HT:PCBM was subjected to be varied and its device performance were evaluated using solar simulator under one sun condition. The physio-chemical characterizations such as UV-Visible, FTIR, PL, XRD, FESEM and AFM were performed for all the materials used in the device fabrications. By varying the spin rate of conjugated polymers/fullerene blends it may helps in scaling up of self-organized molecules of an active layer. Also the variation of spin rate will plays a role in the surface roughness of the film and thereby contributing enhancing the photo-conversion efficiency of fabricated devices. The device fabricated with optimized conditions under ambient atmosphere exhibits efficiency of 1.8 % with J_SC of 5.8 mA/cm² and V_OC of 0.57 V. The performance of the device can be enhanced further by controlling exposure of electrode materials. (author)

[en] Being an alternative for fossil fuels photovoltaics have to overcome traditional structures, procedures, cultures and values. As a new building material photovoltaics also have to deal with the structure and culture of the building sector. In this paper the institutional bottlenecks for the introduction of PV on a large scale are explored in five areas: financing, administration, structure of energy sector, architecture, communication and marketing. Nevertheless, on the whole the developments are encouraging. (author)

[en] In this paper, the recent research progress on triphenylamine (TPA)-based donor-acceptor (D-A) amorphous polymers including our developed polymers is reviewed. TPA has three-dimensional branched structures and can provide D-A polymers containing D and A units in the main chain or side chain. The use of TPA-based amorphous polymers in the fabrication of organic photovoltaics (OPVs) offers great advantages over the use of a polycrystalline film in terms of high reproducibility of the OPV performance. The amorphous polymer design using TPA, therefore, indicates a promising direction for the development of new donor materials in OPVs

[en] With the advancement of synthesis methods, boron nitride nanotubes seem to become increasingly valuable in fundamental physical research and find applications in a number of forms, from dyed neutron-absorbing fabrics to high-temperature catalysts and photovoltaic devices.