Development of a Solar-Tracking System for Horizontal Single-Axis PV Arrays Using Spatial Projection Analysis

Abstract

Uniaxial trackers are widely employed as the frame for solar photovoltaic (PV) panel installation. However, when used in sloping terrain scenarios such as mountain and hill regions, it is essential to apply a solar-tracking strategy with the sloping factors considered, to eliminate the shading effects between arrays and reduce the electricity production loss due to terrain changes. Based on a uniaxial tracker on the sloping terrain of a PV farm located in Ningxia, this study established a uniaxial solar-tracking strategy for sloping terrain by integrating a spatial projection model with a dynamic shadow assessment method. In the proposed strategy, the optimal tilt angle of the PV array and related desirable adjustment are identified taking into consideration major parameters such as the shadow area ratio S and the average solar irradiance intensity G. A tool underpinned by Matlab Simulink has also been developed to realize the proposed solar-tracking strategy. With the input of a simulated ramp signal β and the dynamically changed time parameters, the tracking angle of PV arrays over the simulated duration is accurately predicted, followed by a series of experimental validations conducted on the winter solstice and a typical sunny day (15 September). Moreover, the study also explored the terrain impacts on solar tracking by comparing the sloping terrain and flat terrain applications. The analytic and experimental results indicate that (a) the maximum value of the G(β) function could serve as the input to identify the optimal tracking angle; (b) the application of the flat terrain tracking (FTT) strategy in sloping terrain would result in a reduction of average solar irradiance intensity harvested by the PV arrays with varying degrees; (c) in the context of an east–west −7° sloping terrain, compared with the FTT strategy, the sloping terrain tracking (STT) strategy enabled anti-shading tracking, and then increased the daily PV electricity yield by 0.094 kWh/kWp, which is around 1.48% of the daily energy production; (d) given a measurement with annual scale, the STT strategy could cause a 1.26% increase in the energy harvesting with a flat uniaxial PV array on a −7° slope terrain, achieving an annual increase of 25.16 kWh/kWp. The experimental comparative analysis validated the precision of the proposed solar-tracking model, which has far-reaching significance for achieving automatic solar-tracking of PV modules, as well as improving the capacity and efficiency of PV systems.

A Building-Integrated Bifacial and Transparent PV Generator Operated by an “Under-Glass” Single Axis Solar Tracker

“…When installing a certain number of PV strings on a conventional land single-axis solar tracking system, it is a widespread practice to look for the installation configuration that maximizes the electricity generation of each rotating PV string. To obtain this reasonable goal, it is necessary to avoid any reciprocal shadowing phenomenon that can occur during the daily rotations of the PV strings, which are necessarily installed side by side [30]. Furthermore, it is well known that avoiding reciprocal shadowing phenomena among the PV strings helps to avoid any adverse hotspot phenomenon and maintain their lifespan [31].…”

Simulation and Optimization of a Dual-Axis Solar Tracking Mechanism

“…There are also solutions where both movements are generated from the same motor/actuator, thus making it possible to reduce the cost of the overall system, but with the remark that the energy efficiency of such systems is lower than in the case of two-motor systems [42,43]. Another simplified variant is the one in which only one of the two movements is performed, as the case may be, the diurnal movement or the elevation movement, thus obtaining the so-called single-axis (or mono-axial) tracking systems, with only one degree of freedom [44][45][46][47][48][49][50].…”

Desalination in Spain and the Role of Solar Photovoltaic Energy

“…Currently, uniaxial/single-axis tracking is being implemented more and more, by increasing the energy received without a considerable increase in investment. In horizontal single-axis tracking systems, the PV panel tilt angle is adjusted to maximize the overall irradiance harvesting, which is dependent on the real-time monitoring data and serials of pre-set control rules [47]. These systems produce an increase of around 15~20% in PV electricity generation [48].…”