Decrease In Short-circuit Current Research Articles

Improvement in the aged silicon solar cells parameters by thermal annealing

In this paper, to simulate and accelerate the effects of aging, solar cells were exposed to the different doses of co60 gamma radiation. The current–voltage (I–V) characteristics of mono-crystalline solar cells under AM1.5 illumination condition were studied before and after the gamma irradiation. Experimental results showed that the solar cell parameters such as open circuit voltage (Voc), short circuit current (Isc) and efficiency (η) decrease with the increase of the gamma radiation doses. The effect of subsequent thermal annealing on solar cells degraded by gamma irradiation is investigated. A significant improvement in the electric parameters of by low doses gamma irradiated silicon solar cells is observed after the thermal annealing.

A study of silicon p-n structures with mono- and multifacial photosensitive surfaces

Increase in the efficiency and reduction of silicon consumption in production of solar cells are relevant problems. Designing two and three facial solar cells can be seen as a solution for such tasks. Compared to usual SC, the output power of two and three facial solar cells exceeds by 1.72 times by 2.81 times, respectively. Illumination of solar cells with high intensity light makes the temperature of its heating an important characteristic. Therefore, the paper investigates the influence of temperature on properties of multifacial solar cells. We defined the nature of change of temperature coefficients for the main photovoltaic parameters that are inherent to silicon solar cells under various (one, two and three facial) conditions of lighting. Temperature coefficients of three facial solar cells are 2.52·10–3 V/K for open circuit voltage and 1.8·10–3 K–1 for fill factor of I-V. At temperature change of SC from 300 K to 350 K, the density of short circuit current decreases only by 4 %.

Aspects Regarding the Use of Electronic Power Devices in Power Grid

Abstract Custom power devices are generally used to power sensitive consumers who need higher energy quality. This paper will exemplify some of the custom power devices used in distribution networks. The case study will highlight the solid-state current limiter effects on an electrical network by simulating a medium voltage network. By installing a solid-state current limiter, the value of the short-circuit current decreases; thus, the electrodynamic forces and thermal stresses supported by the components of the electrical network are reduced.

Influence of Dust Deposition on the Electrical Parameters of Silicon-Based Solar Panels Installed in Senegal (Dakar Region)

In recent years, photovoltaic (PV) modules are widely used in many applications around the world. However, this renewable energy is plagued by dust, airborne particles, humidity, and high ambient temperatures. This paper studies the effect of dust soiling on silicon-based photovoltaic panel performance in a mini-solar power plant located in Dakar (Senegal, 14°42'N latitude, 17°28'W longitude). Results of the current-voltage (I - V) characteristics of photovoltaic panels tested under real conditions. We modeled a silicon-based PV cell in a dusty environment as a stack of thin layers of dust, glass and silicon. The silicon layer is modeled as a P-N junction. The study performed under standard laboratory conditions with input data of irradiation at 1000 W/m2, cell temperature at 25°C and solar spectrum with Air Mass (AM) at 1.5 for the monocrystalline silicon PV cell (m-Si). The analysis with an ellipsometer of dust samples collected on photovoltaic panels allowed to obtain the refraction indices (real and imaginary) of these particles which will complete the input parameters of the model. Results show that for a photon flux arriving on dust layer of 70 μm (corresponding to dust deposit of 3.3 g/m2) deposited on silicon-based PV cells, short circuit current decreases from 54 mA (for a clean cell) to 26 mA. Also, conversion efficiency decreases by 50% compared to clean cell and the cell fill factor decreases by 76% - 50% compared to reference PV cell.

Temperature Accelerated Life Test and Failure Analysis on Upright Metamorphic Ga0.37In0.63P/Ga0.83In0.17As/Ge Triple Junction Solar Cells

AbstractA temperature accelerated life test on Upright Metamorphic Ga0.37In0.63P/Ga0.83In0.17As/Ge triple‐junction solar cells has been carried out. The acceleration has been accomplished by subjecting the solar cells to temperatures (125, 145 and 165°C) significantly higher than the nominal working temperature inside a concentrator (90°C), while the nominal photo‐current (500×) has been emulated by injecting current in darkness. The failure distributions have been fitted to an Arrhenius–Weibull model resulting in an activation energy of 1.39 eV. Accordingly, a 72 years warranty time for those solar cells for a place like Tucson (AZ, USA), was determined. After the ALT, an intense characterization campaign has been carried out in order to determine the failure origin. We have detected that temperature soak alone is enough to degrade the cell performance by increasing the leakage currents, the series resistance, and the recombination currents. When solar cells were also forward biased an increase of series resistance together with a reduction of short circuit current is detected. The failure analysis shows that: a) several metallization sub‐products concentrate in several regions of front metal grid where they poison the silver, resulting in a two times reduction of the metal sheet resistance; b) the metal/cap layer interface is greatly degraded and there is also a deterioration of the cap layer crystalline quality producing a huge increase of the specific front contact resistance, c) the decrease of short circuit current is mainly due to the GaInP top subcell degradation.

Analysis of degradation in 25-year-old field-aged crystalline silicon solar cells

Photovoltaic (PV) modules have been in use for more than 25 years. The gradual degradation of PV modules is determined by its components and the solar cells. We analyzed the long-term reliability of solar cells using a 25-year-old field-aged PV module. The power of a large size PV module was reduced by approximately 24.6% owing to the delamination of two specific solar cell portions. For a single cell module from a large size PV module, the decrease of short circuit current (Isc) was caused by the discoloration of the ethylene-vinyl acetate. The maximum power (Pmax) decreased by 11.5% compared with its initial value; however, this is not an effect of the degradation of the solar cell. Despite being manufactured in the 1980s, these solar cells did not fail and have little power loss and excellent durability after 25 years.

Temperature impact on parameters of In0.3Ga0.7As PV cell under laser irradiation condition

The parameters of In0.3Ga0.7As PV cell applied in laser wireless power transmission (LWPT) system dependence on temperature was investigated at a temperature range of 5-90°C under 100mW/cm2 laser intensity with 1070nm wavelength. The pollination algorithm method was used to extract parameters, viz., photocurrent, series and shunt resistance, reverse saturation current, and ideality factor from the I-V curves at each temperature point. The results show that the short circuit current decrease exponentially with temperature increasing, which is obviously different from the condition with solar irradiation. As temperature increases, the conversion efficiency and the open circuit voltage decreases linearly at the rate of 0.095%/°C and 1.89mV/°C, respectively. In addition, the dependence of series and shunt resistance, ideality factor, and fill factor on temperature was also analyzed. This research gives us a new understanding of PV cells under laser irradiation condition, also provides a direction for manufacturing the cells used in LWPT system.

Unlocking the nature of the co-doping effect on the ionic conductivity of CeO2-based electrolyte

Doped CeO2 is a very promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). To further improve the performance of the CeO2-based electrolyte, co-doping two different elements into CeO2 is a feasible method, however the co-doping effect on the ionic conductivity is not well understood and whether it is synergistic or average is even controversial. In order to gain a fundamental understanding of the co-doping effect, the microscopic properties of co-doped CeO2 are calculated using the DFT+U method. Density of states, band structures, oxygen vacancy formation energies, defect association energies, and oxygen vacancy migration energies are systematically calculated for In3+, Sm3+ single-doped and co-doped CeO2. Based on our calculations, we find that the coexistence of the two doped ions in the local structures of the doped CeO2 can suppress the reduction of Ce4+ to Ce3+, which is beneficial for the decrease of the internal short circuit current of the CeO2-based electrolyte. For In3+ and Sm3+ co-doped CeO2, when the distance between the two doped ions is the first nearest neighbor, the co-doping effect is average. However, when the distance between the two doped ions extends to the second nearest neighbor, the availability of the free oxygen vacancies is synergistically enhanced. Therefore whether the co-doping effect on the ionic conductivity is average or synergistic is highly dependent on the local structures of the co-doped CeO2 which are difficult to control in experiments, offering a reasonable explanation for controversial experimental results. Our work provides a new atomistic level insight into the co-doping effect in CeO2 which would be helpful for high performance electrolyte development.

A High-Speed Magnetoelectric High-Power Generator

The efficiency of increasing the power of a magnetoelectric generator (MEG) was investigated in the RMXprt module of the Ansoft Maxwell software package. The MEG under study has four poles. Its magnetic system consists of cylindrical permanent magnets equally spaced over the rotor diameter. The magnetization of the rotor permanent magnets has a radial direction. To determine the thermal state of the MEG, the Solid Works Flow Simulation software package was used. An estimation of efficiency of using the Halbach magnet system in high-speed magnetoelectric energy converters is presented. The influence of the ratio of the rotor pole arc to the pole pitch was investigated, and as a result of the studies it was found that decreasing the pole arc makes it possible to reduce a total harmonic distortion (THD), but a current density increases and short-circuit current decreases. Therefore, when using this method, it is necessary fully to determine all of these parameters. The research results were used as a basis for design of a high-speed liquid-cooled MEG with 450-kW power and a 50 000-rpm rotor speed.

Hydrostatic pressure incubation affects barrier properties of mammary epithelial cell monolayers, in vitro

During lactation, accumulation of milk in mammary glands (MG) causes hydrostatic pressure (HP) and concentration of bioactive compounds. Previously, a changed expression of tight junction (TJ) proteins was observed in mice MGs by accumulation of milk, in vivo. The TJ primarily determines the integrity of the MG epithelium. The present study questioned whether HP alone can affect the TJ in a mammary epithelial cell model, in vitro. Therefore, monolayers of HC11, a mammary epithelial cell line, were mounted into modified Ussing chambers and incubated with 10 kPa bilateral HP for 4 h. Short circuit current and transepithelial resistance were recorded and compared to controls, and TJ proteins were analyzed by Western blotting and immunofluorescent staining. In our first approach HC11 cells could withstand the pressure incubation and a downregulation of occludin was observed. In a second approach, using prolactin- and dexamethasone-induced cells, a decrease of short circuit current was observed, beginning after 2 h of incubation. With the addition of 1 mM barium chloride to the bathing solution the decrease could be blocked temporarily. On molecular level an upregulation of ZO-1 could be observed in hormone-induced cells, which was downregulated after the incubation with barium chloride. In conclusion, bilateral HP incubation affects mammary epithelial monolayers, in vitro. Both, the reduction of short circuit current and the change in TJ proteins may be interpreted as physiological requirements for lactation.

The Solar Panel’s Performance Dependence on Incident Radiation Intensity and its Surface Temperature

The effect of radiation intensity and temperature on the performance parameters of a solar panel is investigated experimentally using an indoor experimental setup, designed and constructed locally at Higher Institute for Applied Sciences and Technology, Damascus. The experiments have been carried out under various intensity levels of radiation in the range of 700- 2000W/m2. The experimental results indicate that, radiation intensity has a dominant effect on current parameters. It is found that photocurrent; short circuit current and maximum current have been increased linearly with increasing radiation intensity. So, concentrating system may be regarded as a best choice to enhance the power output of solar system. The power density of the solar panel at 30oC increased from 1.86 mW/cm2 at 1300W/m2 to 3.59 mW/cm2 at 2000W/m2. The role of temperature on the electric parameters of solar panel is also considered. The practical local possible solar panel’s temperature was considered to be in the range of 10–70oC. The experiments cover this temperature range. Experimental results show that all electrical parameters of solar panel such as maximum output power, open circuit voltage, short circuit current, efficiency and fill factor have changed with temperature variation. As well as the amount of changes in these parameters in terms of temperature value have been obtained. According to results, the most significant is the temperature dependence of the voltage which decreases with increasing temperature while the current of the solar panel slightly increases by temperature. On the other hand, it has been observed that solar panel’s temperature has a dramatic effect on voltage parameters. Open circuit voltage and maximum voltage are decrease with increasing solar panel’s temperature. So, the maximum power density of the mono-crystalline and poly-crystalline silicon solar module decreased from 43.4 and 48.76/cm2 to 36.32 and 41.88mW/cm2 for temperature 10oC and 70oC respectively. When testing the effect of temperature on French Photo watt solar cells, obtained 20 years ago and encapsulated in a solar panel locally, in the temperature range of 10–90oC, it was found that, the open circuit voltage decreases by 1.87mV/ oC which is equivalent to 0.3% of the nominal value. The short circuit current intensity decreases by 20mA/oC which is equivalent to 1% of the nominal value. When comparing these values with those of the company presented at its electronic cite, Isc = +0,06%/°C; Voc = -0,34%/°C, one can conclude that aging effect is important on short circuit current intensity.

Effect of argon plasma treatment on the output performance of triboelectric nanogenerator

Physical and chemical properties of the polymer surface play great roles in the output performance of triboelectric nanogenerator (TENG). Specific texture on the surface of polymer can enlarge the contact area and enhance the power output performance of TENG. In this paper, polydimethylsiloxane (PDMS) films with smooth and micro pillar arrays on the surface were prepared respectively. The surfaces were treated by argon plasma before testing their output performance. By changing treatment parameters such as treating time and plasma power, surfaces with different roughness and their relationship were achieved. The electrical output performances of the assembled TENG for each specimen showed that argon plasma treatment has a significant etching effect on the PDMS surface and greatly strengthen its output performance. The average surface roughness of PDMS film increases with the etching time from 5mins to 15 mins when the argon plasma power is 60W. Nevertheless, the average surface roughness is inversely proportional to the treatment time for the power of 90W. When treated with 90W and 5mins, many uniform micro pillars appeared on the both PDMS surface, and the output performance of the TENG for plasma treated smooth surface is 2.6 times larger than that before treatment. The output voltage increases from 42V to 72V, and the short circuit current increases from 4.2μA to 8.3μA after plasma treatment of the micro pillar array surface. However, this plasma treatment has time-efficient due to the hydrophobic recovery property of Ar plasma treated PDMS surface, both output voltage and short circuit current decrease significantly after 3 months.

Fatigue mechanism verified using photovoltaic properties of Pb(Zr0.52Ti0.48)O3 thin films

The photovoltaic effect and its evolution during electrical fatigue in Pb(Zr0.52Ti0.48)O3 (PZT) thin films have been investigated. It is found that the photovoltaic effect of the as-grown PZT thin film is highly affected by the asymmetric Schottky barriers, which can be tuned by applying an external electric field. During fatigue processes, both open-circuit voltage (Voc) and short-circuit current (Jsc) decrease considerably with the increase of the number of electrical cycles. This phenomenon could be ascribed to the degradation of the interfacial layer between the thin film and the electrode induced by highly energetic charge carriers injected from the electrode during bipolar cycling. Our work sheds light on the physical mechanism of both ferroelectric photovoltaics and polarization fatigue in thin-film ferroelectrics.

Performance Analysis of PV Cell under Uniform and Non-Uniform Illumination

The electrical behavior i.e. short circuit current and open circuit voltage is observed. The effects of different temperature and insolation on I-V and P-V curve are studied considering uniform illumination. The study shows that short circuit current and open circuit voltage increases with increase in the insulation. By multiplying these two powers curve is drawn. As the cell’s working temperature increases short circuit current increases and open circuit voltage decreases and accordingly the power is obtained. Then the effect of non-uniform illumination on PV cell with variable shape factor is studied and temperature variation with non-uniformity is observed. By approaching uniform illumination on PV cell mean temperature decreases and accordingly the current output with the variation of shape factor is studied.

Comparative study between dye-synthesized solar cells prepared by electrophoretic and doctor blade techniques

Comparative study between solar cell sensitized by several naturel dyes and fabricated with two methods: electrophoretic deposition process (EPD) and doctor blade technique (DB) have been presented.TiO2 layers have been deposited on the glass FTO (Fluorine doped tin oxide: SnO2: F) for the tow techniques. Structural and morphological properties were presented and correlated to deposition conditions of growing films. Natural dyes have been prepared and used to realize Dye-Synthetized Solar cells (DSSCs).Developed electrical model was used to study and extract experimental parameters. The compared I – V measurements under 100mW/cm2 illumination have shown an increase in both filling factor (FF) to reach 58.85% and open circuit voltage (Voc) value of 0.66V for mallow sensitized solar cell fabricated with EDP technique. A decrease in short circuit current (Isc) and efficiency (η) due to the TiO2 layer thickness and the cracks appearing in the layer fabricated with EPD technique.

The investigation on the front surface field of aluminum rear emitter N-type silicon solar cells

N-type solar cells with aluminum rear emitter provide high power conversion efficiency and overcome light induced degradation. Meanwhile, since the processes are realized on the existing P-type cells, the fabrication cost gets lower for N-type solar cells. Front surface field (FSF) is an important part in this structure. The functions of FSF are similar to that of Al back surface field in P-type cells. FSF enhances carrier collection ability, increases the cells’ open-circuit voltage, as well as increases the efficiency. In this paper, the FSF profiles were investigated. The appropriate surface concentration was around 4×1020cm−3, meanwhile the depth should be kept between 0.25μm and 0.3μm from the experiment. A too low concentration cannot provide a strong field effect passivation, while a too high concentration will introduce much more recombination centers. A thin FSF layer increased the resistance, while a thick FSF layer made the short-circuit current decrease, because of the degradation of photoelectric response at the short wavelength. Thermal oxidation was introduced in the process. The FSF profiles were also studied. The minority lifetime and efficiency were enhanced after oxidation. The surface concentration of FSF should be adjusted to around 3×1019cm−3. The best cell efficiency has reached to 19.93%, tested by 18th Institute of China Electronics Group Corporation.

The effects of amiloride and age on oxygen consumption coupled to electrogenic sodium transport in the human sigmoid colon.

Background/Aim:Aerobic metabolism is necessary for ion transport in many transporting epithelia, including the human colonic epithelium. We assessed the effects of the epithelial sodium channel blocker, amiloride, on oxygen consumption and short-circuit current of the human sigmoid epithelium to determine whether these effects were influenced by the age of the subject.Materials and Methods:Segments of the sigmoid colon were obtained from the safety margin of resections performed in patients of 62–77 years of age. Isolated mucosa preparations were obtained and mounted in airtight Ussing chambers, fit for simultaneous measurement of short-circuit current and oxygen concentration, before and after blocking epithelial sodium channels with amiloride (0.1 mmol/L). Regression analyses were performed to assess the associations between short-circuit current, oxygen consumption, and age of the subject as well as to define the relationship between the decreases in short-circuit current and oxygen consumption after blockade.Results:Epithelial sodium channel blockade caused an 80% reduction in short-circuit current and a 26% reduction in oxygen consumption. Regression analysis indicated that both changes were significantly related (r = 0.884; P = 0.0007). Oxygen consumption decreased by 1 μmol/h/cm2 for each 25 μA/cm2 decrease in short-circuit current. Neither short-circuit current nor oxygen consumption had any significant relationship with the age of the subjects.Conclusion:The decrease in epithelial oxygen consumption caused by amiloride is proportional to the decrease in short-circuit current and independent of the age of the subject.

Inhibiting MoS2 formation by introducing a ZnO intermediate layer for Cu2ZnSnS4 solar cells

A 10nm ZnO layer have been employed as an intermediate layer between absorber and back contact in Cu2ZnSnS4 thin film solar cells prepared by sulfurization of the metallic stacking layers. By introducing this layer, the device conversion efficiency increases from 2.1% up to 3.3%, open-circuit voltage increases from 476mV to 657mV while short-circuit current decreases from 14.52mA/cm2 to 10.72mA/cm2. The ZnO layer can significantly suppress the reaction of Mo back contact with S and facilitate the reaction between S and metallic stacking layers. It results in the MoS2 thickness decrease from 300nm to 80nm and less unreacted elemental Sn left in the CZTS absorber after sulfurization annealing as shown in transmission electron microscopy images. However, due to the Sn loss through a path of SnS at high annealing temperature, the reacted and eliminated elemental Sn results in a higher density of voids formed at the bottom of sulfurized stacking layers. The improvement in the cell efficiency and open-circuit voltage could be related to both reduced MoS2 thickness and removal of shunting path generated by elemental Sn. However, the voids formation at back contact deteriorates the carrier transportation and decreases short-circuit current.

Ab initio study of electronic effects in the ZnO/TiO2core/shell interface: application in dye sensitized solar cells

Core/shell structure of ZnO nanowires coated with a monolayer of TiO2 is investigated using Density Functional Theory (DFT). The electronic states of the semiconductor is calculated and compared before and after coating of the TiO2 monolayer on a ZnO [10 0] surface. The effect of TiO2 coating induce surface states changes and shifts the conduction and valence band edges to higher energies. Our results, in qualitative agreement with the experimental work of Matt Law et al. (J. Phys. Chem. B, 110, 22652), show an increase in open circuit voltage and a decrease in short circuit current in ZnO/TiO2 core shell dye sensitized solar cells. Regarding the semiconductor density of states (DOS), TiO2 coated ZnO have more conduction band acceptor states and lower electronic back recombination in agreement with experimental results. Surface dipoles are attributed to changes of the local density of states of the surface. This method can be used for more investigation of starting effects of semiconductor interface and helps the study of surface states and their physical origin in dye sensitized solar cells.

The Role of Fullerene Mixing Behavior in the Performance of Organic Photovoltaics: PCBM in Low‐Bandgap Polymers

This manuscript reports the mixing behavior, interdiffusion, and depth profile of 1‐[3‐(methoxycarbonyl)propyl]‐1‐phenyl‐[6,6]C61 (PCBM):low‐bandgap (LBG) polymer thin films that are formed by thermally annealing initial bilayers. The extent of mixing of PCBM is higher in polymers that include the 2,1,3‐benzothiadiazole (BT) unit than in polymers that incorporate the 2,1,3‐benzooxadiazole (BO) unit. This difference is ascribed to the enhanced mixing behavior of PCBM with the benzothiadiazole functionality than with benzooxadiazole functionality, which is attributed to preferred intermolecular interactions. The increased polymer/fullerene mixing is found to be crucial for optimal device performance. A decrease of polymer/fullerene mixing reduces the donor/acceptor interface, which lowers the probability of exciton dissociation and charge generation. Moreover, low PCBM mixing provides limited pathways for electron transport out of a miscible region, due to long distances between adjacent PCBM in such a miscible phase. This inhibits electron transport and increases the recombination of free charge carriers, resulting in a decrease in short circuit current and device performance. These results further exemplify the importance of the thermodynamic mixing behavior of the polymer:fullerene pair in designing next‐generation conjugated polymers for organic photovoltaic (OPV) applications, as this controls the final morphology of the OPV active layer.