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The adoption of photovoltaic (PV) solar systems has been rapidly increasing due to their cost-effectiveness and easy installation. However, the non-linearity of PV panels can hinder their ability to provide maximum power output. To achieve optimal efficiency, it is crucial to track the control point based on irradiance and temperature values. This study proposes an analytical control method that employs the open circuit voltage to track the maximum power point of a PV panel that is connected to a DC microgrid via a DC–DC boost converter. The proposed model considers the temperature effect on both diode saturation current and current generated by irradiance for higher sensitivity. To validate the accuracy of the proposed model, the PV panel installed at the Technopark campus of Gazi University was used for experimentation. The performance indicators, mean absolute percentage error (MAPE) and R2, were calculated to assess the differences between the values calculated from the proposed model and those observed from the experiments. The results indicate an error value of 3.9% and a compatibility of 95.9% based on MAPE and R2, respectively. These findings demonstrate the success of the proposed model. [ABSTRACT FROM AUTHOR]

The state of charge (SOC) is critical for the safety and reliable utilization of the battery. However, SOC estimation accuracy of lithium iron phosphate (LiFePO4) battery is a challenging task because of its flat voltage plateau and its performance is affected greatly by temperature. An improved open circuit voltage (OCV) combined with coulomb counting (CC) method based on the dual input model of ambient temperature and OCV is proposed. This approach is employed to obtain the initial value of SOC based on the dual input model over a wide range of temperature, and to establish SOC estimation model of modified CC with Simulink. The temperature entropy coefficient and differential analysis has been analyzed under different SOC conditions. The SOC maximum errors predicted by the proposed OCV-CC method maintain within 3.10%, while the maximum errors of the traditional OCV-CC increase from 4.78% to 23.64% under the temperature of 35°C ~−15°C. The results show the estimation accuracy of SOC using the proposed OCV-CC method is improved obviously, especially under low temperature. [ABSTRACT FROM AUTHOR]

A structure of pn junction with ferroelectric layer (PbTiO3/pn-Si, or PTO/pn cell) was prepared. Instability of open circuit voltage (Voc) was found in this structure. Voc of the cells will decrease rapidly in the first 40 minutes after poled. The pole condition influence of Voc was investigated. Results show that the instability of Voc comes from the polarization and depolarization effect of the PTO layer in the PTO/pn cells. Purely increasing the poling voltage and time cannot improve the stability of the cells significantly. Poling under high temperature (200 °C) is an efficient way to improve the stability of the cells. Finally variation width of Voc is modified from maximum about 80 mV (−16 V poled, 60 minutes) to about 17 mV (±16 V poled, 200 °C). [ABSTRACT FROM AUTHOR]

We have investigated the effect of two different kinds of cobalt electrolytes on the photovoltaic performance in dye-sensitized solar cells (DSSCs) using the established porphyrin dye (YD-2). We have characterized the photovoltaic performance of DSSCs containing iodide/triiodide and two different Co3+/2+electrolytes to confirm the relationship between redox potential of cobalt(III/II) tris(2,2′-bipridine), [Co(bpy)3]3+/2+, cobalt(III/II) tris(1,10-phenanthroline), [Co(phen)3]3+/2+and the photovoltaic characteristics in DSSCs. Compared to the iodine-based electrolyte, the photovoltage of the DSSCs based on [Co(phen)3]3+/2+was increased by 15%. The current densities in [Co(bpy)3]3+/2+and [Co(phen)3]3+/2+-based devices decrease due to their larger size and decrease in difference bewteen HOMO level of dye and redox potential of electrolytes. [ABSTRACT FROM PUBLISHER]

A single cell solid oxide electrolyte direct carbon fuel cell with two biomass carbon fuel performances is presented in this article. The performances of the wheat carbon fuel are better than those of the spruce fuel. At 800°C the open circuit voltage of wheat fuel (1.18 V) was slightly higher than spruce (1.16 V). The peak power density recorded for wheat fuel was 66.92 mW/cm2while spruce fuel was lower at 57.40 mW/cm2. On the contrast spruce fuel (156.20 mA/cm2) gave a maximum current density with wheat fuel lower at 138.52 mA/cm2. Other electrochemical performances are presented. [ABSTRACT FROM PUBLISHER]

Photovoltaic technology offers great potential in the replacement of fossil fuel resources, but still suffers from high device fabrication cost. Herein, we attempted to provide a solution to these issues with heterogeneous nanostructures. Firstly, Zinc oxide (ZnO)/cobalt oxide (Co3O4) heterojunction nanowires are prepared through facile fabrication methods. By assembling Co(OH)2nanoplates on ZnO nanowire arrays, the ZnO/Co3O4heterogeneous nanostructures are uniformly synthesized on ITO coated glass and wafer. Current (I)-voltage (V) measurement through conductive atomic force microscope shows excellent photovoltaic effect. And, the heterojunction nanostructures shows unprecedented high open circuit voltage. Therefore, the potential application of the heterogeneous nanostructures in solar cells is demonstrated. [ABSTRACT FROM AUTHOR]

In the solar cell module there is a strong correlation between optical and electrical losses. Ideally all the incoming light should be converted to electrical energy and collected by the metal contacts. However, placing metal on the top of the solar cell decreases the fill factor and hence the efficiency of the solar cell. In this paper the analytical and 3D distributed model is presented for top metal grid optimisation for AlGaAs/Si tandem solar cell. 3D distributed model for AlGaAs/Si tandem solar cell, with different grid pattern, is investigated. Results using models are obtained by SPICE simulator. The results of distributed model are compared with the results of analytical model. Power losses due to base resistance of a solar cell are also included in analytical model. [ABSTRACT FROM AUTHOR]

The influence of LiNO3incorporation onto TiO2electrodes on the performance of dye-sensitized solar cells (DSSCs) was studied. LiNO3-incorporated TiO2electrodes were prepared by a dip coating process and the resulting electrodes were applied to DSSCs. Open circuit voltage (Voc) of DSSC with a LiNO3-modified TiO2layer was averagely improved by over 24% compared to that of a reference device with bare TiO2. The conduction band edge shift of TiO2to a negative direction, arising from the formation of a surface dipole, accounted for the improvement inVoc. [ABSTRACT FROM AUTHOR]

The open-circuit voltage (VOC) with respect to the reverse dark saturation current density in planar CuPc/C60and non-planar boron subphthalocyanine chloride (SubPc)/C60organic solar cell (OSCs) devices is compared in the present study. The fabricated OSCs devices were: ITO/CuPc/C60/BCP(90Å)/Al(1000Å) and ITO/SubPc/ C60/BCP(90Å)/Al(1000Å) organic solar cells. We observed that the dark saturation current and the VOCvalues vary in the CuPc/C60solar cells, whereas almost no variation of the dark saturation current and VOCvalues in SubPC/C60solar cells occur. All SubPC devices show almost similar value of dark current. These differences may be attributed to the surface morphologies of planar CuPc and non-planar SubPC donor layers. [ABSTRACT FROM AUTHOR]

Batteries with a higher state of charge in a series-connected battery string have a higher charging power and reach full charge before the overall battery terminal voltage attains its nominal voltage. If a constant charging current is ongoing, the batteries are charged into gassing and are prone to a dramatic reduction in life and potential damage. To equalize the state of charge for a series-connected battery string, an energy-saving charge equalization strategy is presented. Unlike traditional strategies that redistribute the charge energy according to the dynamic battery voltage, the proposed strategy inserts a reasonable rest period between equalization cycles so that the battery open circuit voltage, which serves as a relative state of charge indicator to the charge equalization control, is detectable. The rest period is also advantageous in that it converts the battery charge into chemical energy, and so minimizes undesired by-products, such as gas and heat. The proposed equalization strategy is realized by a peripheral interface controller (PIC) based experimental setup in which a buck-boost converter is used as the charging current redistributor and a push-pull converter is mandatory in order to fully charge the battery string. The experimental results confirm the performance of the proposed strategy. [ABSTRACT FROM PUBLISHER]

In the present study, we have used density functional molecular orbital calculations to investigate the energy levels of the frontier orbitals of novel bisadducts of Phenyl-C71-Butyric-Acid-Methyl Ester (bis[70]PCBM) in an attempt to verify if they can be used as electron acceptor in polymer-fullerene solar cells. C70 derivatives are promising materials for these devices because they have a stronger and broader absorption compared to C60 ones, and they can improve the current output of the corresponding polymer-fullerene solar cells. The calculated LUMO levels for the bis[70]PCBM isomers are higher compared to the monoadduct already used as acceptor in such devices. Since the open circuit voltage (Voc) for devices with ohmic contacts is proportional to the difference between the HOMO of the donor polymer and the LUMO of the acceptor, these bisadducts can increase the Voc of polymer solar cells having poly(3-hexylthiophene) as donor. [ABSTRACT FROM AUTHOR]

This article reports properties of photovoltaic devices containing new donor materials - copolymers referred as PCEMB, composed of 2-(carbazol-9-yl)ethyl methacrylate (CEM) and benzofuran-2-carboxylic acid 2-(2-methylacryloyloxy)ethyl ester (MB). Manufactured photovoltaic cells consisted of donor and acceptor (PBT or P3OT) layers sandwiched between ITO covered glass and evaporated aluminum electrode. Performance of the cell was optimized for a copolymer composed of 8% CEM and 92% MB. The efficiency, found equal c.a. η = 0,03%, was low comparing to other photovoltaic cells reported in the literature. However, following the observed tendencies, it can be supposed that there exists a large reserve for the enhancement of the open circuit voltage through further chemical modifications of the chromophore. In the case of the PDT containing cells, measured Uoc was substantially lower. This fact may be attributed to difference in carrier mobility between this polymer and PCEMB. Simultaneously, the larger sizes of the MB molecule may favor separation of the charges and leads to enhancement of the corresponding voltage. [ABSTRACT FROM AUTHOR]