In order to efficiently solve the problems created by the deepening energy crisis affecting Europe and the world,

\r\ngovernments cannot neglect the opportunities of using the energy

\r\nproduced by sun collectors. In many of the EU countries there are sun

\r\ncollectors producing heat energy, e.g. in 2011 in the area of EU27

\r\n(countries which belong to European Union) + Switzerland altogether

\r\n37519126 m2 were operated, which are capable of producing 26.3

\r\nGWh heat energy. The energy produced by these sun collectors is

\r\nutilized at the place of production. In the near future governments

\r\nwill have to focus more on spreading and using sun collectors.

\r\nAmong the complex problems of operating sun collectors, this article

\r\ndeals with determining the optimal tilt angle, directions of sun

\r\ncollectors. We evaluate the contamination of glass surface of sun

\r\ncollector to the produced energy. Our theoretically results are confirmed by laboratory measurements. The purpose of our work is to help users and engineers in determination of optimal operation

\r\nparameters of sun collectors.<\/p>\r\n","references":"[1] Duffie, J., Beckman, W. 1980. Solar energy thermal processes.\r\nCalifornia: Wiley.\r\n[2] Dickinson, W., Cheremisinooff, P. 1980. Solar energy technology\r\nhandbook. New York: Marcel Dekker.\r\n[3] Patk\u00f3, I. 2010. Integrating renewable energies into the national energy\r\nsystem with special regard to the thermal utilization of solar energy.\r\nConference of the Hungarian Technical Experts; Hungarian Academy of\r\nScience; Budapest.\r\n[4] Patk\u00f3, I. 2009. Renewable energies. University book. Budapest: BMF\r\nPublishing Inc.\r\n[5] Hand, I.F. 1978. Charts to obtain solar altitudes and azimuths. Heating\r\nand Ventilating, October, pp. 86-88.\r\n[6] Patk\u00f3, I., Szeder, A., Patk\u00f3, Cs. 2013. Evaluation the impact tilt angel on\r\nthe sun collectors. Energy Procedia, vol. 32, pp. 222-231.\r\n[7] Ibrahim, R., Andreas, A. 2008. Solar position algorithm for solar\r\nradiation applications. Colorado. Technical Report NREL.\r\n[8] Calabro, E. 2009. Determining optimum tilt angel of photovoltaic panels\r\nat typical north-tropical latitudes. Journal of Renewable and Sustainable\r\nEnergy, vol. 1.\r\n[9] Chang, T.P. 2008. Study on the optimal tilt angle of solar collector\r\naccording to different radiation types. International Journal of Applied\r\nScience and Engineering, vol. 6.pp. 151-161.","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 95, 2014"}