PERFORMANCE OF DIFFERENT PHOTOVOLTAIC TECHNOLOGIES FOR AMORPHOUS SILICON (A-SI) AND COPPER INDIUM GALLIUM DI-SELENIDE (CIGS) PHOTOVOLTAIC MODULES

In this work, the analysis of performance of two types of photovoltaic (PV) (Amorphous Silicon (a-Si) Copper Indium Gallium Diselenide (CIGS) technologies were achieved out under under Iraqi (Baghdad)climate conditions. The elevation of the selected site is 9 m above ground level. The experimental work covered the eight commercially available PV technologies. The two technologies that employed in this work are, Amorphous Silicon (a-Si) and Copper Indium Gallium Diselenide (CIGS). The total period of the experimental work was 7 months, and the data were analyzed simultaneously. Special attention is given to the influence of temperature and solar radiation the performance of the PV modules. Where, it was proposed a simple I-V curve test for PV modules. The results showed that the proposed system successfully experimentally extracted I-V curves of the selected two PV modules (amorphous and CIGS solar modules). The maximum values of power (Pmax) at solar radiation intensity 750 W/m² are 2.742 W, and 2.831 W for amorphous silicon and copper indium gallium di-selenide respectively. This is occurred because the lowest solar module operating temperature (19 oC and 17 oC for solar radiation 750 and 1000 W/m2 respectively) and ambient temperature (7 oC) and for Jan., 2021 than other months. Consequently, the same behavior for the two modules at solar irradiance 1000 W/m2 with the highest power value; 2.680 W, and 3.198 W of amorphous silicon and copper indium gallium di-selenide respectively. Furthermore, the minimum values of power (Pmax) at solarradiation intensity 750 W/m² are 2.530, and 2.831 for amorphous silicon and copper indium gallium di-selenide respectively because we have the highest solar module operating temperature (57 oC, and 55 oC respectively) and ambient temperature (45 oC) for April, 2021 than other months. Consequently, the same behavior for the two modules at solar irradiance 1000 W/m2 with the highest power value; 2.680 W, and 3.198 W of amorphous silicon and copper indium gallium di-selenide respectively. The highest efficiency can be notes for CIGS solar module with a value 7.3%, while the lowest one is 5.5% for amorphous solar module.

Corrigendum to "Numerical Simulation of Copper Indium Gallium Diselenide Solar Cells Using One Dimensional SCAPS Software [J. Nig. Soc. Phys. Sci. 3 (2021) 48–58, https://doi.org/10.46481/jnsps.2021.133]"

The original content of this published Article has an error in the name of one of the co-authors Eli Danladi which was written incorrectly as D. Eli. We highly regret this.

Numerical Simulation of Copper Indium Gallium Diselenide Solar Cells Using One Dimensional SCAPS Software

The effect of multivalent defect density, thickness of absorber and buffer layer thickness on the performance of CIGS solar cells were investigated systematically. The study was carried out using Solar Cells Capacitance Simulator (SCAPS) code, which is capable of solving the basic semiconductor equations. Employing numerical modelling, a solar cell with the structure Al|ZnO : Al|In2S3|CIGS|Pt was simulated and in it, a double acceptor defect (-2/-1/0) with a density of 1014 cm-3 was set in the absorber in the first instance. This initial device gave a power conversion efficiency (PCE) of 25.85 %, short circuit current density (Jsc) of 37.9576 mAcm-2, Photovoltage (Voc) of 0.7992 V and fill factor (FF) of 85.22 %. When the density of multivalent defect (-2/-1/0) was varied between 1010 cm-3 and 1017 cm-3 the solar cells performance dropped from 26.81 % to 16.87 %. The champion device was with multivalent defect of 1010 cm-3 which shows an enhancement of 3.71 % from the pristine device. On varying the CIGS layer thickness from 0.4 um to 3.6 um, an increase in PCE was observed from 0.4 um to 1.2 um then the PCE began to decrease beyond a thickness of 1.2 um. The best PCE was recorded with thickness of 1.2 um which gave Jsc of 37.7506 mAcm-2, Voc of 0.8059 V, FF of 85.2655 %. On varying the In2S3 (buffer) layer thickness from 0.01 um to 0.08 um, we observed that there was no significant change in photovoltaic parameters of the solar cells as buffer layer thickness increased.

Leaching via Weak Spots in Photovoltaic Modules

This study identifies unstable and soluble layers in commercial photovoltaic modules during 1.5 year long-term leaching. Our experiments cover modules from all major photovoltaic technologies containing solar cells from crystalline silicon (c-Si), amorphous silicon (a-Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). These technologies cover more than 99.9% of the world market. We cut out module pieces of 5 × 5 cm2 in size from these modules and leached them in water-based solutions with pH 4, pH 7, and pH 11, in order to simulate different environmental conditions. Unstable layers open penetration paths for water-based solutions; finally, the leaching results in delamination. In CdTe containing module pieces, the CdTe itself and the back contact are unstable and highly soluble. In CIGS containing module pieces, all of the module layers are more or less soluble. In the case of c-Si module pieces, the cells’ aluminum back contact is unstable. Module pieces from a-Si technology also show a soluble back contact. Long-term leaching leads to delamination in all kinds of module pieces; delamination depends strongly on the pH value of the solutions. For low pH-values, the time dependent leaching is well described by an exponential saturation behavior and a leaching time constant. The time constant depends on the pH, as well as on accelerating conditions such as increased temperature and/or agitation. Our long-term experiments clearly demonstrate that it is possible to leach out all, or at least a large amount, of the (toxic) elements from the photovoltaic modules. It is therefore not sufficient to carry out experiments just over 24 h and to conclude on the stability and environmental impact of photovoltaic modules.

Degradation Mechanism Due to Water Ingress Effect on the Top Contact of Cu(In,Ga)Se2 Solar Cells

The impact of moisture ingress on the surface of copper indium gallium diselenide (CIGS) solar cells was studied. While industry-scale modules are encapsulated in specialized polymers and glass, over time, the glass can break and the encapsulant can degrade. During such conditions, water can potentially degrade the interior layers and decrease performance. The first layer the water will come in contact with is the transparent conductive oxide (TCO) layer. To simulate the impact of this moisture ingress, complete devices were immersed in deionized water. To identify the potential sources of degradation, a common window layer for CIGS devices—a bilayer of intrinsic zinc oxide (i-ZnO) and conductive indium tin oxide (ITO)—was deposited. The thin films were then analyzed both pre and post water soaking. To determine the extent of ingress, dynamic secondary ion mass spectroscopy (SIMS) was performed on completed devices to analyze impurity diffusion (predominantly sodium and potassium) in the devices. The results were compared to device measurements, and indicated a degradation of device efficiency (mostly fill factor, contrary to previous studies), potentially due to a modification of the alkali profile.