This paper deals with a simplified and meaningful thermal model used to extract the cell temperature of a photovoltaic (PV) module. This model that takes into account the ambient temperature, incident irradiance and wind velocity is calibrated using a complete experimental database. The results of the thermal modeling provide a heat transfer coefficient law that could be implemented into a PV simulation tool. Two key elements of this approach may be highlighted. The results enable to better calculate the solar energy production of a PV module and to predict the energy efficiency of a PV system.
While single-junction solar cells may be capable of attaining AM1.5 theoretical efficiency of 33.16%, infinite multijunction (MJ, Tandem) solar cells will have a limiting efficiency of 86.8%. Tandem solar cells based on crystalline silicon (c-Si) bottom cells are therefore attracting great interest. An interesting candidate for the top cell absorber is represented by copper zinc tin sulfide Cu 2 ZnSnS 4 (CZTS). In this work, the CZTS/Si tandem solar cell is optimized by using indium oxide / Cadmium sulfide (In 2 O 3 /CdS) hybrid buffer. This present work reports CZTS/Si solar cell with an open-circuit voltage V OC of over 0.942 V and a J SC of 34.7 mA cm − ² by adding In 2 O 3 layer in the CZTS top cell. The added In 2 O 3 layer has a thickness of 0.022 µm and is n-doped with a concentration of 1e20 cm −3 . Compared with a CZTS/Si in which the hybrid buffer is of CdS, the efficiency is increased from 13.5% to 28.4%. These hybrid In 2 O 3 /CdS buffers provide a promising way to reduce the V OC deficit and further boost the efficiency of CZTS/Si solar cells.
Multilevel inverters are well used in grid connected domestic photovoltaic applications because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. However, this kind of inverter has to be modified to both limit common-mode currents and improve the robustness of the system. This paper presents a new mixed 5-level inverter that meets these challenges. The operating principle of the converter is proposed. Several experimental measurements are described to validate this new concept. The output voltage and current and the THD of the output voltage are particularly discussed.
Multilevel inverters are well used in high power electronic applications (about 10 kW) because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. However, inverter architecture must be modified in order to take into account the different photovoltaic (PV) problems in conventional installation. This paper presents a comparative study of 5-level Neutral Point Clamped (NPC) and a new mixed 5-level inverter. The theoretical study is validated using simulation with the LTspice environment. The output voltage and total harmonic distortion are particularly compared. An experimental 5-level inverter was realized in order to validate analytical results.
This paper deals with a new highly modular simulation tool, named as "PVLab" and developed by the GREMAN laboratory, to better size photovoltaic (PV) installations. The programming structure and the physical models implemented within this simulation tool are explained. Several case studies are proposed to highlight the relevance of this new simulation tool. The yearly virtual electrical energy production results of grid-connected PV plants are discussed. In particular, these results are compared with the PVsyst tool ones. PVLab has a high level of flexibility, allowing modifying the physical models and databases (for instance, meteorological data) according the users' needs. This is permitted through the expertise in all the computing steps and particularly, the MATLAB development environment. Controlling the source code gives itself a huge potential in the field of renewable energy applications in comparison with PVsyst which is currently the commercial reference. This point is particularly discussed at the end of the paper.
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