This paper proposes an algorithm to calculate the optimum tilt angle of solar panels by means of global horizontal solar radiation data, provided from Earth-based meteorological stations. This mathematical modeling is based on the maximization of the theoretical expression of the global solar irradiation impinging on an inclined surface, with respect to the slope and orientation of the panel and to the solar hour angle. A set of transcendent equations resulted, whose solutions give the optimum tilt and orientation of a solar panel. A simulation was carried out using global horizontal solar radiation data from the European Solar Radiation Atlas and some empirical models of diffuse solar radiation. The optimum tilt angle resulted was related to latitude by a linear regression with significant correlation coefficients. The standard error of the mean values resulted increased significantly with latitude, suggesting that unreliable values can be provided at high latitudes. 1. Introduction Most countries in the world have realized the need for reduction of gases emission to contrast the adverse global climatic change, encouraging the use of renewable and sustainable sources of energy. Indeed, large quantities of carbon dioxide, nitrogen, and sulfur oxides are emitted in the world by conventional energy sources, which are released to the earth’s atmosphere contributing to climate change. Furthermore, the world will soon run out of its conventional energy resources because of the rapid depletion of fossil fuel reserves. This future scenario and the risks associated with CO2 emissions and global warming have increased the interest in renewable energy. The major renewable energy systems include photovoltaics (PVs), solar thermal, wind, biomass, hydroelectric, and geothermal. However, among various renewable energy sources, the photovoltaic technology for power generation is considered well-suited technology, particularly for distributed power generation. Solar panel is the energy conversion fundamental component of PV systems or solar collectors. Solar panels use light energy from the sun to generate electricity through the photovoltaic effect, whereas solar thermal systems generate heat. The amount of electrical power produced from PV systems is related to the amount of solar irradiation projecting on the modules. Hence, the global solar irradiation on tilted surfaces facing in different directions should be considered to estimate thermal and electrical power obtained in architectural planning. The literature provides that solar power supplied by the modules
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