African Journal of Science, Technology, Innovation and Development - latest Issue
Volume 8, Issue 4, 2016
Source: African Journal of Science, Technology, Innovation and Development 8, pp 327 –330 (2016) http://dx.doi.org/http://dx.doi.org/10.1080/20421338.2015.1118867More Less
In this work, we have used a one-dimensional simulation program called the solar cell capacitance simulator (SCAPS) to design solar cells with the structure SnOx/CdS/CIGS (SnOx window, CdS buffer and CIGS absorber material) and study their performance. To improve efficiency we have used a grading layer of CIGS but with different band-gaps. Cu(In,Ga) Se2 has grading band-gaps varying in range from 1.04 to 1.68 eV, with the corresponding Ga content x = 0 to 1. The grading layer used improves the open-circuit voltage (VOC) and also the short-circuit current density (JSC). Photovoltaic parameters were determined using the current density-voltage (J-V) curve. In addition, we have studied the effects of operating temperature on grading layer CIGS solar cells. Our numerical simulation gives some important indications to lead to higher efficiency of CIGS solar cells.
Source: African Journal of Science, Technology, Innovation and Development 8, pp 331 –339 (2016) http://dx.doi.org/http://dx.doi.org/10.1080/20421338.2015.1118869More Less
This paper proposes modelling approaches for photovoltaic (PV) modules with a fast and simple numerical method of modelling, the Newton-Raphson method, as the first step. This method has several electric circuit models. We selected and tested the two most convincing models, the 1-D model and the 2-D model, and deduced that the 2-D model faithfully reproduces the curve I(V) of the PV module. This numerical model is used in the calculation of equation parameter extracts from the curve I(V) given in the standard test conditions (STC), but sometimes we donâ??t have all these parameters. Therefore, to achieve an appropriate characterisation of the behaviour of PV modules, we tested and validated, as a second step, the second method of modelling based on artificial intelligence and specifically artificial neural networks to deduce the I(V)STC curve through the ANN model, and in order to have a complete modelling for electrical PV modules.
Source: African Journal of Science, Technology, Innovation and Development 8, pp 340 –342 (2016)More Less
This work aims to improve the performance of solar cells with structure SnO2/CdS/CIGS/Mo by using the solar cellcapacitance simulator (SCAPS-1D). Our idea is to insert the SnS layer between the absorber layer CIGS and the Mo(molybdenum) back contact. A maximum conversion efficiency of 24.45% (VOC = 0.78 V, JSC = 38.66 mA/cm2, FF = 0.80) was achieved with 1 μm-CIGS absorber layer, 50 nm-CdS buffer layer, 200 nm of ZnO window layer and 300 nm of SnS BSF layer. This study shows that ultra-thin CIGS solar cells with a BSF layer give better results compared to the work of Gloeckler (2005), which presented an efficiency of 19.62% ((VOC = 0.61 V, JSC = 39.23 mA/cm2, FF = 0.81) with 3 μm thickness of CIGS in the structure ZnO/CdS/CIGS/Mo. In addition to this, the cells' stability with temperature was studied and analysed.
Effectiveness and efficiency of national systems of innovation : a comparative analysis of Ghana and KenyaSource: African Journal of Science, Technology, Innovation and Development 8, pp 343 –356 (2016) http://dx.doi.org/http://dx.doi.org/10.1080/20421338.2015.1128037More Less
This paper presents a comparative analysis of the determinants of the effectiveness and efficiency of the Ghana National System of Innovation (GNSI) and the Kenya National System of Innovation (KNSI) for crafting evidence-based policy. Two regression analyses are performed respectively on the level of innovativeness of business enterprises (BEs) (effectiveness) and of the strength of linkages between research institutes (RIs) and the production system (efficiency) using an array of independent variables culled from the national systems of innovation (NSI) literature. We find first that the effectiveness of the GNSI and KNSI are positively associated with actor linkages in both, and diffusion and capacity of ICT with respect to Ghana; the efficiency of the GNSI and KNSI are positively related to diffusion and rate of access to ICT and negatively to lack of finance with respect to Ghana, while negatively associated with actor linkages - i.e. government and arbitraguer linkages - with respect to Kenya. In both countries the strength of RIs linkages with the production system is a significant determinant of NSI effectiveness; and the level of innovativeness of BEs is a significant determinant of NSI efficiency.
Author Alex BaraSource: African Journal of Science, Technology, Innovation and Development 8, pp 357 –368 (2016) http://dx.doi.org/http://dx.doi.org/10.1080/20421338.2016.1156839More Less
Diffusion and adoption of an innovation are as equally critical as the creation of the innovation for without them, the innovation becomes redundant. The level of technology in developing countries reflects the pace at which technology diffuses within countries. Transfer, adoption and adaption of knowledge to low income countries, therefore, constitute an important issue for economic growth and global development. Developing countries, being net adopters of innovations, face a number of "external" factors which act as barriers or enhancers of diffusion of innovation. This notwithstanding, studies on innovation adoption/diffusion carried out in Zimbabwe are mostly concentrated on the demand side, focusing on end-user behaviour, ignoring "external" and supply side factors. This paper extends beyond the end-user adoption analysis to look at effects of cross-country flow of innovation (cross country diffusion), internal regulation, macroeconomic factors and supply side factors on diffusion of financial innovations in Zimbabwe. Case studies and examples reviewed in this study clearly demonstrate that for Zimbabwe, determinants of diffusion of financial innovation are indeed beyond end-user attributes.