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• Solar tracking is a crucial task in efficiently harvesting solar power in a PV plant. • Horizontal Single-axis tracking systems require a precise estimation of its axis' orientation. • This methodology uses available data to accurately estimate the tracker's orientation. • This methodology estimates height differences in adjacent trackers. • The improve tracking and backtracking strategies increase production by 1%. Photovoltaic (PV) energy production is becoming a more significant part of the energy mix world-wide due to its clean origin, supportive and cost reductions. Therefore, it is increasingly important to develop methodologies to improve efficiency and reduce energy losses. Solar tracking is a way of increasing the irradiance over the PV field and, subsequently, boosting energy production. Both single-axis and double-axis tracking systems (SATS & DATS) are well known methods but both require not only a proper estimation of the sun's position but also precise knowledge of the tracker's position and orientation. Several factors (construction, design, configuration) can cause the values used to calculate the optimal tracking to be inaccurate, thus increasing production losses. This paper proposes a methodology to calculate the actual orientation of the trackers' axis based on the energy production of its associated strings. Additionally, it provides the height differences between adjacent trackers by detecting shading patterns. This information is key to defining more efficient tracking and backtracking strategies the avoid row-to-row shading and, overall increasing energy production. The proposed method is applied to a real 5 MW facility, identifying misalignments of several degrees in most trackers that were causing annual losses (1 %), not only due to inaccurate tracking but also row-to-row shading. [ABSTRACT FROM AUTHOR]

• Half-cut cells are the new standard for solar photovoltaic modules. • Standard backtracking can be outperformed by more sophisticated approaches. • Yield optimisation can reduce levelised cost of electricity up to 12% • Increasing full load hours of single-axis tracking systems possible with shading. • Power density optimisation important for future solar-driven energy system. Optimisation of horizontal single-axis tracking solar photovoltaic power plants is important for its optimal application. Commonly, standard backtracking has been applied to avoid mutual shading and improve the full load hours and levelised cost of electricity; however, this approach is not always the best solution for state-of-the-art modules with half cell technology. Backtracking has not yet been studied for different test sites with different solar and climatic conditions. This study aims to improve the knowledge on the techno-economic performance of horizontal single-axis tracking systems with half cell modules applying different backtracking strategies in full hourly resolution for nine test sites globally and varying row spacing. In addition to the standard backtracking algorithm, an advanced backtracking algorithm that varies the tracking angle only if the irradiance can be improved, and an advanced sophisticated backtracking algorithm simulating the irradiance for all possible tracking angles, are studied. The results confirm that standard backtracking is only superior for specific conditions. Compared to no backtracking, standard backtracking shows up to ca. 9% higher levelised cost of electricity due to lower full load hours. Advanced backtracking can lower the levelised cost of electricity by up to 9% and advanced sophisticated backtracking by up to 12%, due to improved full load hours. In general, results are similar and comparable for all test sites studied. This study highlights the importance of backtracking for optimised future horizontal single-axis tracking system planning. [ABSTRACT FROM AUTHOR]

• A new tracking strategy with backtracking for PV plants is analysed. • Maximum irradiance is achieved even during backtracking. • Impacts of the design variables of PV plants with this tracking plan are studied. • Design criteria for PV plants with the suggested tracking strategy are proposed. • PV Plants could provide, at least, 2% more energy using this tracking strategy. Photovoltaics is experiencing significant growth because it is a renewable energy resource capable of contributing positively to the global energy system. However, the high variability in solar resources and the inter-collectors shadows negatively influence the energy conversion of a photovoltaic plant, making it necessary to develop technologies that minimize these negative aspects. Considering these issues, this paper analyses the influence of the design variables of a PV plant with two-axis tracking (collector size and distance between collectors) on its energy conversion. For that purpose, the tracking/backtracking strategy considered has two important advantages: it allows eliminating the inter-collector shading and optimizes the collection of global solar irradiance during both tracking and backtracking, by considering not only the optimization of direct component of solar irradiance but also the diffuse and reflected components. Based on this analysis, specific design recommendations are proposed for two-axis tracking PV plants located in Cordoba (Spain). It has been proved that differences in orientation between the collectors running according to this tracking/backtracking strategy and those with pure astronomical tracking increases when the clearness index decreases. Similarly, the results show that the period of time requiring backtracking during sunrise and sunset is longer when GCR decreases. In any case, it has been shown that photovoltaic plants in Cordoba with this new tracking strategy could provide annually, at least, 2% more energy than plants using some existing tracking strategies, even those defined as ideal. Hence, this tracking/backtracking strategy might significantly contribute to the development of photovoltaic plants with two-axis trackers. [ABSTRACT FROM AUTHOR]

In this study, we have performed an analysis of potential irradiation increase across Europe, derived from moving photovoltaic (PV) modules to a horizontal position during cloudy and overcast situations. The motivation of research is that PV technology has expanded outside countries endowed with high solar irradiation and it is nowadays present in high-latitude regions and areas with frequent cloud cover. Unlike concentrating solar technologies, PV panels can make use of both beam and diffuse irradiance. During cloudy or overcast situations, most of solar irradiance comes from the diffuse component, which approaches an isotropic behavior under those circumstances. Then, a PV panel facing the zenith would receive more irradiation than a PV panel following the Sun’s path. In our approach, we have used data from several Baseline Surface Radiation Network stations. Results showed a yearly potential irradiation increase of 3.01% with respect to a reference single-axis tracking system (SATS) in the northern-most station. Values for other stations were correlated to climate. Thus, the sunniest station would increase its annual irradiation by 0.16% compared to a reference SATS. Daily irradiation increases of up to 19.91% were registered. Two predictive models were created to develop a SATS, which could determine in advance the optimum position of PV panels. Model 1, which was based on the persistence of irradiance, was designed to work real time in order to increase production. Yearly gains of up to 2.51% of irradiation were registered. However, Model 2 was developed to update production forecasts in the intra-day electricity markets so that PV plant owners can maximize their revenues. It is based on irradiance predictions from a numerical weather prediction service and underperformed current SATS. [ABSTRACT FROM AUTHOR]