Development of Winter Season Optimal Tilt Angle Model for Fixed Tilted Plane PV Installation in Akwa Ibom State, Nigeria

Akpan Ikoedem Ekpenyong, Anthony Mfonobong Umoren, Idorenyin Markson


In this paper, a polynomial model is developed for determining the winter season optimal tilt angle for fixed-tilt PV installations in Uyo metropolis, Akwa state of Nigeria. Satellite-derived NASA SSE  solar radiation data  was used in the  study and the simulation was done using PVSyst software. The polynomial  model is given as  WTF(β)= -0.00013(β^2 ) + 0.00643(β) + 0.99991; where WTF(β)  is the winter average transposition factor and β is the tilt angle in degrees. The model has prediction accuracy of 99.92% with root mean square error of 0.001267 and optimal winter season tilt angle of 24.73°. Furthermore, the study also did the comparison of the effect of using seasonal or yearly fixed tilt and seasonally adjusted tilt angle for the PV panel.  The results show that the greatest yearly average transposition factor is obtained when the tilt angle is optimally adjusted to suit the Winter months during the Winter and to suit the Summer months during the Summer seasons.


Photovoltaic; Irradiation; Tilt Angle; Azimuth Angle; Transposition; Transposition Factor; Optimal Tilt Angle; Fixed Tilted Plane; Winter Optimal Tilt Angle

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Aggarwal R. K. (2013). Estimation of Total Solar Radiation on Tilted Surface. Journal of Environmental Engineering and Technology, Vol. 2, No. 1, 4-6.

Thornton, P. E., Hasenauer, H., & White, M. A. (2000). Simultaneous estimation of daily solar radiation and humidity from observed temperature and precipitation: an application over complex terrain in Austria. Agricultural and Forest Meteorology, 104(4), 255-271.

Ramachandra, T. V., Jain, R., &Krishnadas, G. (2011). Hotspots of solar potential in India. Renewable and Sustainable Energy Reviews, 15(6), 3178-3186.

Mondal, M. A. H., & Islam, A. S. (2011). Potential and viability of grid-connected solar PV system in Bangladesh. Renewable energy, 36(6), 1869-1874.

Breyer, C., & Schmid, J. (2010). Global Distribution of optimal Tilt Angles for fixed tilted PV Systems. Proceedings of the: 25th European Photovoltaic Solar Energy Conference and Exhibition/ 5th World Conference on Photovoltaic Energy Conversion, Valencia, Spain, 4715-4721.

Khan, M. J., & Iqbal, M. T. (2004). Wind energy resource map of Newfoundland. Renewable Energy, 29(8), 1211-1221.

Rigollier, C., Bauer, O., & Wald, L. (2000). On the clear sky model of the ESRA—European Solar Radiation Atlas—with respect to the Heliosat method. Solar Energy, 68(1), 33-48.

Huld, T., Šúri, M., & Dunlop, E. D. (2008). Comparison of potential solar electricity output from fixed‐inclined and two‐axis tracking photovoltaic modules in Europe. Progress in photovoltaics: Research and Applications, 16(1), 47-59.

Gueymard, C. A. (2009). Direct and indirect uncertainties in the prediction of tilted irradiance for solar engineering applications. Solar Energy, 83(3), 432-444.

Elminir, H. K., Ghitas, A. E., El-Hussainy, F., Hamid, R., Beheary, M. M., & Abdel-Moneim, K. M. (2006). Optimum solar flat-plate collector slope: case study for Helwan, Egypt. Energy Conversion and Management, 47(5), 624-637.

Nahar, N.M. (2003). Year round performance and potential of a natural circulation type of solar water heater in India. Energy and Buildings, 35(3), 239-247.

Hottel, C. (1954). Performance of Flat Plate Energy Collectors: Space Heating with Solar Energy. MIT Press: Cambridge.

Löf, G.O.G.; Tybout, R.A. (1973) Cost of house heating with solar energy. Solar Energy, 14(3), 253-278.

Chinnery, D.N.W. (1981). Solar Heating in South Africa. CSIR-Research Report 248: Pretoria.

Kern, J., Harris, I. (1975). On the optimum tilt of a solar collector. Solar Energy 17(2), 97-102.

Heywood, H. (1971). Operating experience with solar water heating. Journal of the Institution of Heating and Ventilation Engineers, 39, 63-69.

Yellott, J.I. (1973). Utilization of sun and sky radiation for heating and cooling of buildings. ASHRAE Journal-American Society of Heating Refrigerating and Air-Conditioning Engineers, 15, 31-42.

Lewis, G. (1987). Optimum tilt of solar collectors. Solar and Wind Technology, 4(3), 407-410.

Lunde, P.J. (1980). Solar Thermal Engineering: space heating and hot water systems. Wiley: New York, 1980.

Perpinan, O., Lorenzo, E., & Castro, M. A. (2007). On the calculation of energy produced by a PV grid‐connected system.Progress in Photovoltaics: research and applications, 15(3), 265-274.

Lorenzo, E. (2003). Energy collected and delivered by PV modules. Handbook of photovoltaic science and engineering, 905-970.

NASA surface meteorology and solar energy-location. Atmospheric Science Data center. Twenty two years average data of NASA SSE model (1983–2005).


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