Ahmed Ghitas

A multicrystalline silicon solar cells in the range of 10 × 10 cm 2 and thickness ~ 278 µm are manufactured by phosphorus diffusion on p-type wafer. Etching methods are necessary to use, in order to remove sawing damages of the unpolished multicrystalline silicon wafer surface after wire cutting and lapping. The resistivity of the sample surfaces are measured by the four-point probe technique. The average surface resistance of the sample lies between 31 to 45 ohm/cm 2 . Those surfaces with minimal resistance values are selected to be used as front surfaces. Silver printing is used as the front fingers contact. The enriched P + layer is prepared by pasting Al layer on the back surface with firing, and the Al is used as a rear cell contact. Characteristic curves of the cells without antireflection coating layer are measured using Solar Cell Tester (at NRIAG). The comparison among the cell samples is evaluated to find the optimal cell parameters (to achieve a high efficiency low-cost m...

The series connection effect on the electrical perf ormance of a large area multicrystalline Silicon so lar cell (21 cm × 21 cm) with back contact technology has be en considered in a desert area. Short circuit curre nt, open circuit voltage and output power are the major elec trical parameters normally characterise the solar c ells.The current shunt measuring technique has been used to avoid th e problems encountered with traditional measuring m ethods. Achieving the optimum electrical short circuit curr ent has been investigated. For this reason, two sim ilar cells have been connected in series and their short circuit cu rrent has been measured. Then, the short circuit cu rrents of the three cells and four cells have been obtained as we ll. These different connections short circuit curre nts have been studied to determine the most suitable number of ce lls that compiles with the used shunt resistance va lue. Furthermore, the correlated open circuit voltages a nd output powers have...

A solar concentrator of the type V-Trough is designed for a multipurpose integrated solar energy project in Helwan of Egypt. A suitable place in the NRIAG is selected. A concentration ratio matching the stability of the unconventional cooling technique for PV module 2.3 is chosen. A new cooling system with heat pipes for the module is manufactured. The optimum angles of setting the system for a maximum performance during the year are calculated using a ray tracing technique. The optimum dimensions of the PV module are 100 cm × 35 cm with an output voltage of 11.4 V and an output current of 4.29 A. The results show that establishing a solar thermal PV project with these conditions is promising for providing energy for off-grid local multipurpose integrated solar energy projects in that area.

The electrical performance of a module consisting of four identical large area multicrystalline silicon solar cell units connected in series has been studied in a desert area under ambient conditions. Each cell is of area 21cm×21cm with back contact technology where the current collected by the fine finger grid is led to the back side through 25 holes. On the back side there are 25 soldering pads for each polarity. Short circuit current and open circuit voltage have been measured to describe the module electrical performance. Short circuit current values are obtained by measuring the voltage developed across a known resistance using the current shunt measuring technique to avoid the problems encountered with traditional measuring techniques. Current shunt is not only very stable under a wide range of ambient temperatures but also it has an identical linearity equation, consequently it is safely used in desert areas to obtain the short circuit currents. Furthermore, applying it in th...

Photovoltaic modules are operated as DC devices. But they exhibit a complex impedance due to the solar cell design. Subsequent electronic circuits for electric power conditioning are designed to match the input at standard operating conditions. During operation the real part as well as the imaginary part of the impedance of photovoltaic modules change due to ambient conditions such as illumination level and temperature. A mismatch due to changes of the complex impedance can lead to a reduced performance of the whole power generating system. Hence, for designing such efficient high power photovoltaic systems a detailed study on AC parameters of solar cells are important. In terrestrial applications, the solar cell is exposed to temperatures varying from 10 o C to 50 o C. Therefore, to study the potential effect of temperature on system performance, the AC parameters (cell capacitance and cell conductance) of silicon solar cells are determined at different temperatures using AC small ...

Oxygen radio-frequency (RF) plasma technique is one of the most novel directions used to improve the physical and chemical properties of graphene oxide (GO). Herein, plasma treatment is used to enhance the chemical functionalization and reduced levels of the GO material for electronic and solar cell applications. GO films were chemically synthesized with high quality and uniformity. Then, they exposed to surface modification using RF oxygen plasma at a processing power of 100 W at different processing times. The microstructure and surface chemistry of the GO films were characterized by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Moreover, the effect of oxygen plasma on the thermal stability, surface roughness, contact angle, work of adhesion, wettability, spreading coefficient, and electrical properties have been studied. The results revealed a decrease in the amount of oxygen-containing groups (such as epoxides, carbonyls, and carboxyl groups) from 48.8% in pristine GO to 36.15% after 5 min of oxygen plasma treatment. Besides, the carbonyls groups (C = O) disappeared while new chemical bonds were created compared to the pristine GO film such as hybridized carbon atoms (SP3) and carboxyl's (O–C = O). Accordingly, the electrical conductivity increases from 0.11 S/m of pristine GO to an optimum value of 0.46 S/m after 5 min of plasma treatment, as a result of the incorporation of high amount of carboxyl, hydroxyl and carbonyl groups. The current results indicate that the properties of GO can be tuned by varying the degree of oxidation, which may pave the way for new developments in GO-based applications.

This study outlines the impact of Co doping on the structures, morphologies, optical, and photochemical activities of nanoporous CdS films for efficient solar energy conversion. A sequence of nanotextured films of cadmium cobalt sulfide (Cd1 − xCoxS; where x = 0, 0.02, 0.04, 0.06, and 0.08) were grown on glass substrates using spray pyrolysis method followed by annealing at 300 °C for 2 h. The grown Cd1 − xCoxS films are of single wurtzite phase and polycrystalline nature. The preferential crystallographic growth of Cd1 − xCoxS nanocrystallites along the (002) is changed to (101) direction for x ≥ 0.06. The crystallite size and lattice parameters are decreased for x ≤ 0.04. Also, the absorption is increased and the optical bandgap is decreased to 2.40 eV at 6% Co-doping. The morphological study reveals the growth of agglomerated pure CdS nanorods. The incorporation of Co increases the density of nanorods, which self-assembled to form nanoporous surface at 2 and 4%. A random distribution of irregular nanorods accompanied by patterned spherical clusters is observed at 6%, which is assembled to a nanoporous pattern at 8%. The photocatalytic performances and reaction kinetics of the films are investigated for methylene blue dye decomposition under sunlight and artificial light illumination. The 6% Co-doped film reached the complete removal after 240 min under sunlight irradiation. This film showed higher stability than pure CdS film for 7 runs. Therefore, the combination of spray pyrolysis and adjustable doping level is a viable way for producing large-scale and reusable photocatalytic films for eco-friendly removal of dyes from industrial wastewater. Cd1 − xCoxS nanofilms of different doping levels (0 ≤ x ≤ 8%) have been designed. Morphological, structural, and optical properties of Cd1 − xCoxS films were studied. The photocatalytic performance and stability of Cd1 − xCoxS films were investigated Cd0.94Co0.06S film is the most suitable film for MB dye degradation under sunlight. Reaction kinetics and reusability are studied under sunlight and artificial light. Cd1 − xCoxS nanofilms of different doping levels (0 ≤ x ≤ 8%) have been designed. Morphological, structural, and optical properties of Cd1 − xCoxS films were studied. The photocatalytic performance and stability of Cd1 − xCoxS films were investigated Cd0.94Co0.06S film is the most suitable film for MB dye degradation under sunlight. Reaction kinetics and reusability are studied under sunlight and artificial light.

The Sun is the primary source of energy responsible for governing both the weather and climate of Earth. Changes in the amount and type of energy Earth receives alter its weather and climate. The variability of the solar flux during the solar cycle occurs mainly in the ultraviolet and especially at wavelengths below 250 nm where it may exceed 3% and even 20 to 40% in the far UV (FUV). This spectrum does not reach the surface: it is completely absorbed by stratospheric ozone and oxygen, playing an important role in the stratosphere where it modifies the fields of temperature, pressure and wind and therefore the conditions of propagation of atmospheric waves that couple the lower and upper layers of the atmosphere. A Space Weather and Ultraviolet Solar Variability microsatellite (SWUSV), is proposed to monitor UV and FUV (Lyman-Alpha 121.6 nm, 200-220 nm Herzberg continuum) in imaging and irradiance (radiometers). This for early precursor Flares and CMEs detection in Lyman-Alpha for S...

Presented at the ARSEC 5th – 7th Nov. 2006 in Bahrain, to be published ... Measurement of silicon solar cells ac parameters ... 1Institute for Material Physics, Faculty of Physics, Vienna University, Strudlhofgasse 4, A-1090 Vienna, Austria, E.mail: Viktor.Schlosser@univie.ac.at

The wind is an inexhaustible resource that can provide significant quantities of energy to support a country's needs. In this paper, the statistical data of two years wind speed measurements of the Helwan city, Cairo, Egypt are used to find out the wind energy potential. The measurements were carried out by weather station installed above the new building of NRIAG at Helwan (Latitude = 29.5 o N, Longitude = 31.2 o E, Elevation=130 m). Also, other wind characteristics with the help of the meteorological data are assessed to evaluate of which at a height above ground level and in open area. The purpose of this study is to reveal that; the wind potential of this region is suitable for electric wind application in a large-scale or can be adequate for non-grid connected electrical and mechanical applications, such as wind generators for local consumption, battery charging, water pumping, and other utilities.

ABSTRACT The performance of the solar cell is influenced by the spectral solar distribution. The silicon solar cell spectral response does not totally coincide with the solar spectrum. In the case of sun light exposure at outdoor conditions, the shapes of the cell spectral response curves are slightly different than that of under simulated light exposure. This paper is interested in studying the effect of variation of solar radiation during the partial eclipse on the output short circuit current and open circuit voltage of the monocrystalline and amorphous silicon solar cells. Also, the spectral cell behaveiour in terms of the solar eclipse was investigated. The ultimate goal is to explain some of an interesting natural phenomenon by using the solar cell spectral response.

A V-trough concentrator with a two-axis tracker system to increase the performance of photovoltaics was designed by the authors and installed on the roof-top of the building of the National Research Institute of Astronomy and Geophysics at Helwan in South Cairo. The V-trough concentrator system comprises two flat mirrors with dimensions 50 cm × 18 cm. They are fixed with the reflecting surfaces facing each other with a separation of about 11 cm, on a wooden table of 50 cm axis length. A sample of polycrystalline and amorphous silicon solar cells were fixed into the system, and similar solar cells of each type were fixed separate to the system, to estimate the electrical gain. The measurements were performed daily at different air masses for one complete year. The temperature of the solar cells in and out of the system were measured for comparison. Also, measurements for beam and global solar radiation and other meteorological conditions were recorded. The optical losses of the syste...