Novel Interconnection Method for Micro-CPV Solar Cells

Tuning the hole transport layer in the Ca3SbI3 absorber-based solar cells to improve the power conversion efficiency

A large area of sunlight onto solar cells is gathered by concentrating system for spacial concentrating solar array, which reduces the amount of solar cells by increasing light intensity onto the solar cells of the unit area. Under concentrating conditions, the short-circuit current, open-circuit voltage, fill factor, efficiency, operating temperature and strong thermal-electrical coupling characteristics of concentrating solar cells are different from the conventional solar cells because of the high intensity and high operating temperature. The concentrating module design, solar cell selection, and design of solar cell heat-dissipation have been carried out. The thermal-electric coupling model of special concentrating photovoltaic system has been established. The relationships among concentrated ratio, substrate-thickness, thermal conductivity of substrate-material and solar cell’s temperature, density of short-circuit current, open-circuit voltage, maximum output power have been analyzed, which provide a view to a reasonabl0e match and selection of multi-parameters in engineering design. Results show that the concentrated ratio has an overall effect on the open-circuit voltage, short-circuit current, efficiency and operating temperature of the solar cell. There is a strong coupling relationship among the parameters, and the positive and negative impacts caused by the concentrating characteristics should be weighed in the engineering design. The short-circuit current density of concentrating solar cells is proportional to the concentrated ratio. Under the lower concentrated ratio circumstance, fill factor and efficiency is not substantially affected by the concentrated ratio. The maximum output power and open-circuit voltage increase with the increase of concentrated ratio. Temperature of concentrating solar cells has an adverse effect on the open-circuit voltage, efficiency and output power, which needs high efficient radiator measures to be taken. The operating temperature of solar cells could be decreased significantly by the high thermal conductivity of the substrate-material. The concentrated ratio between 9~15 is recommended for spacial solar array, which not only embodies the advantage of concentrator like improving the cell-efficiency and decreasing the cost, but also doesn’t exact the deploying precision of concentrating system.

ABSTRACTi-ZnO layers were deposited as diffusion barriers fabricated by RF sputtering on stainless-steel substrates (SUS430, matches with AISI SUS24). It was found that the addition of ZnO layer between stainless-steel substrate and Mo back contact film deplete diffusion of metal ions from substrate and reduce recombination at CIGS layer, as identified by an SIMS depth profile, QE and C-V measurements. With such diffusion barriers, the efficiency, open-circuit voltage, short-circuit current and fill factor of CIGS solar cells all increased, compared to reference cells without diffusion barrier. For the better device performance, Na was supplied during Mo back-contact layer deposition by co-sputtering of the target, including Na-source. Efficiencies of cells were increased with increasing the quantity of Na source. Unlike barrier thickness effect, short circuit current was reduced and open circuit voltage, fill factor were increased with increasing Na-source, and achieved 12.6% efficiency without AR(anti-reflection) coating. The relationship and causality between these results and the Na-doping were analyzed using C-V measurements.

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.

This paper describes a novel hybrid silicon photo voltaic structure with a tremendous three times enhancement in open circuit voltage and short circuit current. This is a considerable result in a photo voltaic device with 0.196 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> effective surface area and porous layer on the top surface of the p-type poly-silicon substrate. This substrate is covered with gold layers on both sides following by a titanium dioxide layer and an indium tin oxide layer on the top surface, respectively. An aluminum layer at the back surface completes this novel architecture. The technique of the creation of pores on the p-type substrate resulted in a significant enhancement in open circuit voltage from 17mV to 44 mV and short circuit current from 2.64 μA to 7.66 μA. The fill factor (FF) was also improved from 23% to 24%.

The effect of 1 sun illumination for 24 h on encapsulated inverted organic photovoltaic devices is studied through a series of electrical and optical characterizations for donor/acceptor polymer solar cells based on poly(dithienogermole‐alt‐thienopyrrolodione)/[6,6]‐phenyl C71 butyric acid methyl ester blends. Power conversion efficiency is significantly reduced after light exposure due to a 45% drop in the device fill factor and a 40% drop in both the open circuit voltage and short circuit current. The decrease in open circuit voltage is attributed to a reduction in the built‐in field in the device due to photodegradation of the ZnO interlayer. The reduction in fill factor and short circuit current is shown to be due to the formation of an extraction barrier for hole collection as a result of photodegradation of the MoOx interlayer. Using a 400 nm long pass filter to block the UV light, device stability is significantly enhanced, resulting in a decrease in power conversion efficiency of less than 5% under the same operation conditions.

Modeling and simulation of nanorods photovoltaic solar cells: A review

Growth of Sn(O,S)2 buffer layers and its application to Cu(In,Ga)Se2 solar cells

In this paper, a theoretical investigation to the effect of the series resistance ( ) on the solar cell output parameters, such as efficiency (η), open-circuit voltage ( ) , output maximum power ( ) , fill factor (FF) and short circuit current( ) was performed. Multisim software was used to achieve the investigation. It is reproduced by using the current-voltage (I-V) characteristics in accordance with double-diode modeling of the solar cell. The results showed that there is a change in the characteristic curve form due to the variation of series resistance values between (0.01- 0.5) Ohm. Moreover, it was found that the fill factor, short circuit current, and open circuit voltage decreased linearly when the value of the series resistance increased. Consequently, the conversion efficiency of the solar cell declined. In other words, the series resistance has a significant effect on the performance of the solar cell.

High-efficiency photovoltaic technology including thermoelectric generation

Photovoltaic (PV) power generation technology is the main renewable energy utilization technology. However, dust deposition severely affects the PV power generation efficiency and decreases the production capacity of PV power plants. In this study, the factors affecting PV technology were divided into the following three types: occlusion, corrosion, and temperature rise. A dust-collecting PV model considering dust deposition and rainfall scouring was established; a PV performance index was proposed. By conducting experiments with different dust mass densities, it was found that the short-circuit current (SCC), open-circuit voltage (OCV), and PV output power of PV decreased with the increase in dust mass density. In the initial stage of dust deposition, dust exhibited the greatest effect on the performance of PV. In the later stage of dust deposition, the effect of dust deposition became stable. The initial 10 g/m2 dust decreased the PV output power by 34%. In addition, the conversion efficiency and fill factor (FF) decreased with the increase in dust mass density; both of them were exponential functions. When the dust mass density was low (less than 30 g/m2), the dust mass density increased by 10 g/m2, and the conversion efficiency decreased by an average of 3.4%. Finally, by conducting economic calculations, it was found that a PV power plant where dust has not removed for one year will cause 12% loss of power generation.

Dye-sensitized solar cells were fabricated using anodized titanium oxide. An aqueous solution of 0.5 wt % HF was used for the electrolyte and platinum plate was used for the counter electrode in the anodizing process at a voltage of 20 V. We obtained well-arranged titanium oxide nanotubes with diameters of 80-150 nm. The anodic titanium was coated with the dye (Ruthenium 535 bis-TBA). A dye-sensitized solar cell was fabricated with lodolyte PMI-50 (Solaronix™) as the electrolyte and a Pt (200 nm)/ Ti (50 nm)/ glass substrate as the counter electrode. The short circuit current (I SC ), open circuit voltage (V oc ), fill factor (FF) and energy conversion efficiency of this cell were 0.54 mA/cm 2 , 0.103 V, 39 % and 0.0022%, respectively. When a current density of 2.0x10 -3 mA/cm 2 was applied to the titanium oxide electrode, the I sc , V oc , FF and energy conversion efficiency were 0.24 mA/cm 2 , 0.675 V, 30 % and 0.050 %, respectively. When the cells were coated with the dye and current was applied, the I sc , V oc , FF and energy conversion efficiency were 0.88 mA/cm 2 , 0.54 V, 24 % and 0.11 %, respectively.

Nanowire Solar cells (NW SCs) have shown hopeful advance for light absorption and charge carrier transport because in a vertical structure absorption and carrier transport are orthogonal to each other. In this work high-efficiency back-contact back-junction (BC-BJ) structures like emitter wrap through and metallization wrap through Silicon (Si) SCs for one-sun applications were studied. The top portion of the device gets fully illuminated and there is no loss incorporated due to the absence of front metallization. Key parameters were extracted of proposed structure and a vertical NW SC structure with a front contact using 3D-TCAD simulation tool. First of all a comparison in the performance is observed between a planar solar cell (PSC) and a NW SC, then two different types of all back contact (ABC) structures are studied. The entire work is simulated using AM1.5G solar spectrum at room temperature. The key solar parameters like open circuit voltage (VOC), short circuit current (ISC), fill factor (FF), short circuit current density (JSC) and conversion efficiency are calculated. The efficiency of the proposed structure is more comparable to a regular NW structure which is considered with similar device characteristics.

Streaming Process for Electrode-less Electrochemical Deposition (SPEED) method is used to create complex thin-film structures, such as KBNNO, in a single step, in contrast to hydrothermal approaches with separate nanoparticle growth and deposition processes. This new ferroelectric oxide [KNbO₃]_1-x[BaNi_1/2Nb_1/2O _3-δ]_x or “KBNNO” has an alloy-tunable band gap as low as 1.1 eV, so that its absorption can be tailored to match the solar spectrum. At the same time, it has a reasonably large polarization allowing for charge separation across the bulk, sizeable photocurrents, and open-circuit voltages V_oc that exceed the band gap, potentially leading to efficiencies that exceed those possible for standard pnjunction cells. Physical characterization of KBNNO films demonstrate the microstructure and stoichiometry of SPEEDproduced thin-films, ratio of elements needed to achieve an ideal band gap of ~1.39 eV, the effect on film chemistry, microstructure, and band gap of annealing, the practical separation of excited carriers at room temperature, the maximum achievable polarization and its temperature dependence, and the conditions for ideal poling. Photovoltaic characterization of KBNNO cells will determine the efficiency, the relative strengths of dark and photo currents, the open circuit voltage, the short circuit current, and cell fill factor (FF).

Exploratory studies on some electrochemical cell systems