Technical note Optimal angles for harvesting solar electricity in some African cities V.N. Dike * , T.C. Chineke, O.K. Nwofor, U.K. Okoro Atmospheric Physics Group, Imo State University, P.M.B 2000 Owerri, Imo State, Nigeria article info Article history: Received 26 June 2010 Accepted 2 August 2011 Available online 1 September 2011 Keywords: PVGIS Optimal Inclination angle Photovoltaic modules Solar irradiation Electricity African cities abstract In recent years, the quest for renewable and sustainable energy has been extensive while solar energy has been on the vanguard of sustainable alternative and renewable energy sources due to its clean nature and cost effectiveness for most human activities such as water pumping and electric power generation, amongst others. The off beam installation of Photovoltaic (PV) modules has posed a severe challenge to the optimal functioning of these PV cells despite the abundance of solar irradiation receivable in most African cities. This paper presents the Optimal Inclination Angles (OIA) for mounting PV modules in the absences of a mechanized or automated solar tracking device, for optimum yield in solar electricity generation for some selected African cities using the Photovoltaic Geographic Information Systems (PVGIS) dataset. The OIA of the selected African cities has been identified for optimal solar irradiation exploitation and if the modules are mounted on a horizontal plane, it is expected that considerable amount of solar irradiation would not be harnessed as it has been estimated using the difference from the Irradiation on OIA (Hopt) and the Irradiation on horizontal plane (Hh), whose difference shows that the northern African cities, Algiers, Rabat and Tripoli, are seen to have high levels in unutilized solar irradiation of 780 Wh/m 2 , 760 Wh/m 2 and 680 Wh/m 2 respectively while Harare, Lusaka, Maiduguri, Khartoum, Maputo and Luanda would have considerably high levels in untapped solar irradiation of 360Wh/m 2 , 330 Wh/m 2 , 180 Wh/m 2 , 260 Wh/m 2 , 570 Wh/m 2 and 80 Wh/m 2 respectively if PV modules are mounted on horizontal plane. However cities such as Bangui, Abidjan and Mogadishu have quite low levels in unexploited solar irradiation of 40 Wh/m 2 , 70 Wh/m 2 and 10 Wh/m 2 respectively when PV modules are mounted on horizontal plane. These differences show the amount of solar irradiation which if adequately harnessed, adds to the solar energy potentials of the region. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Recently, the solar power is one of the world’s most vastly valued renewable energies. Numerous numerical models have been developed with the aim of estimating and maximizing solar radi- ation collection [1e3]. This substantial evidence has continued to inform and attract individual/organizational investment in solar electricity. It is imperative since increasing access to energy is very critical to ensuring socioeconomic development in the world’s poorest and developing countries [4]. Their situation is exacerbated by continued unpredictability of the world market prices for conventional energy sources. Oil in particular, poses a serious risk to world economic and political stability with dramatic effects on energy-importing developing countries [5,6]. These traditional energy sources are facing increasing pressure on a host of environmental fronts because it is the prime source of CO 2 emis- sions which is growing at the rate of 0.5% per year [7]. This is immoderate because of the looming threat of climate change. The EU is implementing challenging commitments to reduce carbon dioxide emissions in accord with the Kyoto protocol [8]. Solar energy can help to diversify energy supply, as well increase energy security since an estimate of 1.5 billion people in developing countries have no access to electricity with about 80 per cent of these people living in sub-Saharan Africa [9]. This problem is most acute in the rural areas but access to electricity will improve their socio-economic status as well as living standards in areas of health, education, communication and access to clean water. Renewable energy development or utilization vis-à-vis solar irradiation agenda should start with assessment of energy potential at the site or region of interest. This is important in the planning, sizing and inclining solar devices [10e13]. Photovoltaic (PV) elec- tricity is currently growing world-wide by almost 50% per annum and the European policy goal is to increase the share of this particular renewable energy technology 100-fold by 2010, * Corresponding author. Tel.: þ234 8068808091. E-mail address: asldikvin@yahoo.com (V.N. Dike). Contents lists available at SciVerse ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2011.08.001 Renewable Energy 39 (2012) 433e439