{"title":"A convergence algorithm for maximum power point tracking of photovoltaic arrays with bypass diodes","authors":"Brandon Contino, Guangyong Li","doi":"10.1109/PVSC.2015.7356293","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7356293","url":null,"abstract":"The performance of a photovoltaic (PV) array is affected by many factors, including its integration into a system. Without a maximum power point tracking (MPPT) algorithm, the PV array will operate at the voltage of its load, which often is not the maximum power point (MPP); therefore, causing the PV array to not produce its maximum power output. This paper discusses a current MPPT technique (Perturb and Observe (P&O)), and presents a new MPPT algorithm, convergence. This new algorithm allows for accurate operation with PV arrays containing bypass diodes. All MPPT algorithms discussed are tested through simulations performed on a model PV array in MATLAB.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126651408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theoretical exploration of Cd-free CIGS solar cells with a charged tunneling electron collector layer","authors":"W. Xu, C. Ke, S. Venkataraj, J. Wong, R. Stangl","doi":"10.1109/PVSC.2015.7355886","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7355886","url":null,"abstract":"Beyond the common cadmium-free copper indium gallium (di) selenide (CIGS) solar cell made with a physical buffer layer of zinc sulfide (ZnS) or indium sulfide (In2S3), a newly devised Cd-free cell using a charged tunneling layer is explored theoretically in this work. In principle, applying an ultra-thin tunnel layer (for example by atomic layer deposition) with a high positive fixed interface charge density, the conventional buffer layer can be substituted. Assuming a fixed interface charge density of 1013 cm-2 of the tunneling layer, the simulated CIGS efficiency is over 15%, being close to the reference CIGS solar cell with CdS buffer layer. The benefits and limitations of the Cd-free tunneling layer CIGS solar cells are discussed. Potential processes suitable for realizing the tunneling layer are also discussed.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129160974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shi Liu, Xin-Hao Zhao, Calli M. Campbell, Maxwell B. Lassise, Yuan Zhao, Yong-Hang Zhang
{"title":"Significantly improved carrier lifetime and reduced interface recombination velocity for CdTe/MgCdTe double heterostructures","authors":"Shi Liu, Xin-Hao Zhao, Calli M. Campbell, Maxwell B. Lassise, Yuan Zhao, Yong-Hang Zhang","doi":"10.1109/PVSC.2015.7356225","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7356225","url":null,"abstract":"The carrier lifetime of CdTe/MgCdTe double heterostructures has been enhanced significantly up to 2.1 μs through using 30 nm Mg<sub>0.48</sub>Cd<sub>0.52</sub>Te barriers. Temperature-dependent photoluminescence measurements indicate that the radiative recombination contributes significantly to the total recombination at room temperature, and the internal quantum efficiency is estimated to be 40 %. A radiative and a non-radiative lifetimes have thus been calculated to be 5.25 μs and 3.5 μs, respectively. The interface recombination velocity of CdTe/Mg<sub>0.48</sub>Cd<sub>0.52</sub>Te is determined to be smaller than 2.7 cm/s, which is better or very close to the best values reported for GaAs/AlGaAs and GaAs/Ga<sub>0.5</sub>In<sub>0.5</sub>P double heterostructures.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124202084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Olopade, O. Oyebola, A. Adewoyin, David O. Emi-Johnson
{"title":"Modeling and simulation of CZTS/CTS tandem solar cell using wxAMPS software","authors":"M. Olopade, O. Oyebola, A. Adewoyin, David O. Emi-Johnson","doi":"10.1109/PVSC.2015.7355783","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7355783","url":null,"abstract":"Device modeling and simulation of a mechanically stacked CZTS (top)/CTS (bottom) tandem solar cell have been carried out in this study. The variation of the absorber layer thickness of the CZTS top cell shows that the CZTS/CTS tandem cell could achieve an AM 1.5G conversion efficiency of 13.8% with an optimized CZTS and CTS cell structure. The open circuit voltage and fill factor values of the CZTS top solar cell are probably the reasons for this efficiency.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123447926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Boccard, L. Ding, Priyaranga Koswatta, M. Bertoni, Z. Holman
{"title":"Evaluation of metal oxides prepared by reactive sputtering as carrier-selective contacts for crystalline silicon solar cells","authors":"M. Boccard, L. Ding, Priyaranga Koswatta, M. Bertoni, Z. Holman","doi":"10.1109/PVSC.2015.7356167","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7356167","url":null,"abstract":"With high quality silicon wafers nowadays available at a low cost, further technology improvement relies on the development of inexpensive and highly efficient carrier-selective contacts (CSC). To this respect, evaporated MoOx hole-selective contacts recently brought some attention due to impressive transparency and carrier selectivity properties, and other materials are widely studied in other photovoltaics technologies (TiO2, WO3, V2O5, ...). Compared to standard heterojunction devices using amorphous silicon as passivating layer and CSC, reported efficiencies for devices using evaporated MoOx layers still fall short due to carrier extraction or recombination issues. Whereas little room for maneuver is foreseen to tune the properties of evaporated metal oxide layers, reactive sputtering on the other hand is expected to allow manipulating the work-function of metal oxides. We will review in this presentation the potential of using reactively sputtered metal-oxides as CSC in c-Si solar cells. Preliminary results obtained with MoOx indicate that decreasing the oxidation state of the layer yields better transport properties but poorer selectivity. Also, though a drastic drop in lifetime was observed after sputtering a MoOx layer on a passivating a-Si layer, annealing enabled a recovery of most of the lifetime.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123639557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cost, performance, and yield comparison of eight different micro-inverters","authors":"S. Krauter, J. Bendfeld","doi":"10.1109/PVSC.2015.7355821","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7355821","url":null,"abstract":"To investigate efficiency and yield of most micro-inverters available on the world market in 2013-14, an outdoor test field on the University of Paderborn has been set up. The inverters have been fed by identical & calibrated crystalline silicon PV modules of 215 W at STC. To monitor accurately AC power output and yield, each of the micro-inverters has been equipped with a calibrated precision electricity meter. For micro-inverters that require control units for grid-feeding this has been purchased also. The test field is equipped with pyranometers in the module plane for global and diffuse irradiance, temperature, wind speed and wind direction measurement. The comparison includes energy yield over almost one year, efficiency-load characteristics, recovery times after switch-off, cost comparisons (including control units necessary and wiring), basic safety, reliability, warranty duration comparisons, and lifetime costs for generated electricity. While the market is quite new, the range of purchase costs varies considerably between the models in comparison, sometimes inverter costs are higher than module costs.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123641400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Epitaxial growth and layer transfer of InP via electrochemically etching / annealing of porous buried InP layers: A pathway for III–V substrate re-use","authors":"X. Kou, M. Goorsky","doi":"10.1109/PVSC.2015.7356347","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7356347","url":null,"abstract":"High crystalline quality InP is epitaxially grown on porous InP layers and characterized. Etching the wafers in hydrochloric acid with different concentrations and current densities create a dual layer porous structure with a more dense top layer for epitaxial growth and a buried porous layer. Annealing the structure forms voids in the buried layer. Epitaxial layers with thickness of about 2 μm were grown on dense layers. The layers grown were analyzed by transmission electron microscopy and high resolution x-ray diffraction and determined to be high quality single crystal layers. The porous samples created were bonded to PDMS substrates and the top layer was easily peeled off due to fracture through the high porosity layer. Layer transfer was also performed by gluing the samples to glass slides and pulling them apart. The transferred layers were characterized by scanning electron microscopy. These results point to the usefulness of porous III-V layers as templates for epitaxial growth and device transfer for solar cell applications.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121260791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Giraldo, M. Neuschitzer, S. López‐Mariño, Y. Sánchez, H. Xie, M. Colina, M. Placidi, P. Pistor, V. Izquierdo‐Roca, A. Pérez‐Rodríguez, E. Saucedo
{"title":"Large performance improvement in Cu2ZnSnSe4 based solar cells by surface engineering with a nanometric Ge layer","authors":"S. Giraldo, M. Neuschitzer, S. López‐Mariño, Y. Sánchez, H. Xie, M. Colina, M. Placidi, P. Pistor, V. Izquierdo‐Roca, A. Pérez‐Rodríguez, E. Saucedo","doi":"10.1109/PVSC.2015.7356377","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7356377","url":null,"abstract":"This work presents a radically new approach based on the application of very small Ge quantities on the CZTSe surface (from 1 nm to 25 nm thick Ge layers), allowing for a liquid assisted improved crystallization due to the formation of a Ge-Se (Se-rich) liquid phase. This modification improves the charge transport properties at this interface and consequently the device's voltage and electro-optical properties in general. Using TEM and TOF-SIMS we demonstrate that Ge is barely incorporated into the absorber; nevertheless we observe a drastic increase of the VOC of the solar cells (from 405 mV for the reference to 470 mV for the best Ge modified one). This in turn has a large impact on the performance, increasing it from 7.0% (reference) to 10.1% (Ge modified), which sets a new record efficiency for a Ge containing kesterite and a VOC among the highest obtained for Se-based kesterite solar cells. First characterizations indicate that this is related to an improved grain growth assisted via Ge-Se liquid phases, the minimization of Sn-reduced species and the formation of Ge-O nano-clusters. Our approach not only allows to go towards high efficiency concepts and to contribute to solve the voltage deficit problems in kesterites, but also opens new perspectives for the possible band-gap engineering of kesterite devices with very low Ge concentrations.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121391956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Concept of a split tandem photovoltaic window","authors":"M. Jobin, Cédric Pellodi","doi":"10.1109/PVSC.2015.7355633","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7355633","url":null,"abstract":"We present a concept of a split tandem photovoltaic window, where the larger wavelengths solar radiations are sent towards horizontal silicon solar cells while short wavelength solar radiations are directed on transparent large band gap solar cells, either dye-sensitized or organic solar cells (DSSC and OSC respectively). We first evaluate the expected enhancement in them of conversion efficiency and then describe the construction of a mini module of this window.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121427077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High speed spectroscopic ellipsometry technique for on-line monitoring in large area thin layer production","authors":"C. Major, G. Juhász, Z. Lábadi, M. Fried","doi":"10.1109/PVSC.2015.7355640","DOIUrl":"https://doi.org/10.1109/PVSC.2015.7355640","url":null,"abstract":"Non-destructive analyzing tools are needed at all stages of thin film process-development, especially photovoltaic (PV) development, and on production lines. In the case of thin films, layer thicknesses, micro-structure, composition, layer optical properties, and their uniformity are important parameters. Off-line point-by-point mapping can be effective for characterization of non-uniformities in full scale PV panels in developing labs but it is slow in the on-line mode. Last years [M. Fried et al, Thin Solid Films 519, 2730 (2011); 571, 345 (2014)], a new instrumentation was developed that provides a line image of spectroscopic ellipsometry (wl=350-1000 nm) data. Prototypes have built for 300-600-900 mm nominal width different structures (poly-Si/c-Si, ZnO/Mo, a-Si/Al, a-Si/glass) on rigid substrates. Thin layers (ZnO/a-Si:H;) on plastic foil substrates were also investigated in roll to roll operation, measurements and results of different structures are presented.","PeriodicalId":427842,"journal":{"name":"2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)","volume":"235 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116174162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}