The optimal design for photovoltaic power plants on sites with a general slope

Some of the characteristics of sloping terrain may favour the development of PV power plant projects. However, the deployment of the solar trackers must be optimised in order to avoid significant production losses due to the azimuth angle and the angle of inclination of the terrain. Such optimisation leads to a complex problem, involving 14 variables. The optimal choice of azimuth angle (γ) and tilt angle (α) of a solar tracker for terrain defined by a given azimuth angle (γg) and tilt angle (αg) is by no means trivial. This is the main objective of this paper. Moreover, an optimal PV power plant design requires inter-row spacing that avoid shading between adjacent PV modules in addition to determining the ideal operating periods. Numerical values are presented for 10 locations in the Northern Hemisphere, with terrain azimuth angles between 0(°) and ±45(°), and terrain tilt angles between 0(°) and 15(°). The following main conclusions can be highlighted: (i) The robustness of the derived equations was proven by validating them from three points of view: numerical validation, validation using PVsyst and Mathematica software and experimental validation; (ii) The azimuth angle of the PV system located at high latitudes is strongly affected by the azimuth angle of the terrain. In contrast, at low latitude locations, the azimuth angle of the terrain has very little influence; (iii) The azimuth angle of the PV system, if the latitude of the site is kept constant, is affected by the weather conditions throughout the year; (iv) Regarding energy gain (EG), for PV system site latitudes between 6(°) and 19(°), the optimal deployment does not achieve significantly better results than deploying the PV system in a southerly direction. In contrast, if this comparison is made at locations with latitudes above 19(°), the EG is significant: (a) The higher the latitude, the higher the EG; (b) The higher the γg, the higher the EG; and (c) The higher the αg, the higher the EG. Using Almeria as a baseline for comparison purposes, with αg=5(°), γg=20(°) and EG=240 (Wh/m2), the EG is 390 (Wh/m2) in Helsinki with the same parameters. When γg=30(°) in Almeria, the EG is 530 (Wh/m2). When αg=15(°) in Almeria, the EG is 1030 (Wh/m2). (v) Regarding LCOE efficiency, for latitudes between 6(°) and 19(°), the values obtained are similar to those provided by the southward deployment of solar trackers. For latitudes higher than 19(°) the following hold: (a) The higher the latitude, the higher the LCOE of the optimal deployment. (b) The higher the azimuthal terrain angle, the higher the LCOE, and (c) The higher the terrain tilt angle, the higher the LCOE. Therefore, it can be concluded that the deployment of PV systems at high latitudes is strongly affected by the azimuth angle of the terrain.