Single-axis Tracking Research Articles

Detection of tracker misalignments and estimation of cross-axis slope in photovoltaic plants

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.

Impact of double-axis tracking on thermal performance of the linear Fresnel Collector: An experimental study

Due to the concerning trend of fossil fuels destructive effect on the environment, renewables, especially solar energy, can be a promising alternative to meet the world's energy demands. Linear Fresnel Collectors (LFCs) are solar thermal collectors that can effectively provide the required thermal energy for various applications. Despite the low capital cost and non-complicated structure of the LFCs, they have some drawbacks, such as end loss effects that reduce their optical and thermal efficiencies. The current research introduces a mechanical tracking system to enable the system to rotate in the secondary axis to decrease the end loss effect. Four experimental tests at laminar and turbulent flows in two single and double-axis tracking modes have been performed to investigate the non-illuminated length in each scenario. Moreover, a theoretical study was conducted, and the results were compared with the experiments. The results showed that the thermal efficiencies were 8.67 %–22.03 % and 40.97 %–63.5 % for the double-axis tracking mode in laminar and turbulent, respectively. The double-axis tracking system enhanced the system's thermal efficiency by 18.91 % and 6.42 % for laminar and turbulent flows on average, respectively, compared to the single-axis tracking. Furthermore, the difference between the experimental and theoretical non-illuminated length values was calculated as 4.14 % and 8.44 % on average for laminar and turbulent flows, respectively. Finally, according to the economic analysis, 4.78 years was calculated for the payback time of the investigated system.

Shaded fraction and backtracking in single-axis trackers on rolling terrain

A generalized closed-form equation for the shaded collector fraction in solar arrays on rolling or undulating terrain is provided for single-axis tracking and fixed-tilt systems. The equation accounts for different rotation angles between the shaded and shading trackers, cross-axis slope between the two trackers, and offset between the collector plane and axis of rotation. The validity of the equation is demonstrated through comparison with numerical ray-tracing simulations and remaining minor sources of error are quantified. Additionally, a simple procedure to determine backtracking rotations for each row in an array installed on the rolling terrain (varying in the direction perpendicular to the tracker axes) is provided. The backtracking equation accounts for a desired shaded fraction (including complete shade avoidance) as well as an axis-collector offset. Test cases are provided to facilitate implementation of these equations.

Quantifying spectral albedo effects on bifacial photovoltaic module measurements and system model predictions

AbstractWe provide a comprehensive analysis of the effect of spectral albedo on photovoltaic (PV) module measurements and system model predictions. We demonstrate how to account for albedo in indoor bifacial device measurements by adjusting the applied irradiance using the scaled rear irradiance method, exemplified on fabricated silicon heterojunction (SHJ) modules. System model performance is studied using a detailed 3D finite‐element model, DUET, for fixed‐tilt and horizontal single‐axis tracked (SAT) arrays between 15 and 75°N. Spectral effects cause variations in measured SHJ module short‐circuit current up to 2% and efficiency variation up to 0.3% abs. We further demonstrate that rear‐side spectral mismatch factors (SMMs) resulting from including or omitting spectral albedo in PV system modeling vary between ±13%, while total (front+rear) SMMs vary up to 3%, depending on the deployment configuration and latitude. SAT array SMMs are weakly correlated with latitude, while fixed‐tilt array SMMs increase with latitude, driven by an increasing proportion of ground‐reflected light on the front‐side of modules. Ground‐reflections can constitute between 2% and 32% of total incident module irradiance, with notably high (>10%) contributions for fixed‐tilt arrays at high latitude. Effects of spectral albedo are most significant for: (1) fixed‐tilt deployments at high latitudes, (2) wide bandgap technologies such as perovskite and cadmium telluride cells, (3) albedos which vary steeply over the technology's absorption range, and (4) high albedo ground covers. Overall, we demonstrate that omitting spectral albedo effects can result in PV measurement and system‐level modeling uncertainties on the order of several percent in these cases.

Single or dual axis trackers, control systems and electric drive losses for photovoltaic applications

This paper deals with the solar trackers for photovoltaic applications. The solar trackers for photovoltaic system assure that the highest possible share of the available solar radiation reaches the surface of the photovoltaic modules. The electric drive which enables tracking is considered as the loss of the energy produced in the photovoltaic system. The electric power consumption of the photovoltaic tracking system will be written as a function of the angle change.

Evaluating the 7E impact of solar photovoltaic power plants at airports: a case study

The deployment of solar panels at airports offers numerous benefits, such as clean energy production, cost savings, emission reduction, improved energy security, and a positive public image. In this study, the performance of various solar panel technologies is investigated based on the 7E framework (i.e. energy, exergy, economic, energoenvironmental, exergoenvironmental, energoenviroeconomic, and energoenviroeconomic) at airports in Pakistan. Initially, available spaces at five international airports are identified followed by energy assessments conducted with PVSyst simulation software. Next, a mathematical model is developed to evaluate exergy, economic, energoenvironmental, exergoenvironmental, energoenviroeconomic, and exergoenviroeconomic parameters. Results show that all airports demonstrate favorable performance ratios. Specifically, Quetta airport emerges as the optimal location as per the 7E assessment, showcasing a reference yield of 2752 kWh/kW, final yield of 2420.8 kWh/kW, 27.63% capacity utilization factor, 0.031 $/kWh levelized cost of electricity, 5730 tons of CO2 avoided annually, and $488,826 per year in greenhouse gas revenue, achieved through thin film-based technology with single axis tracking. Peshawar airport stands out for its high energy efficiency, while Karachi airport excels in exergy analysis. The outcome of the study will provide insights into the potential of these systems to mitigate energy challenges, considering economic feasibility and environmental implications.

A Comparative Experimental Performance Analysis for Fixed Solar PV Systems and Solar Tracker PV Systems in a Tropical Region

Solar photovoltaic (PV) systems promise a reliable future for renewable energy adoption, with the capability for mitigating greenhouse gas emissions and combating climate change while providing a sustainable energy solution to the planet. This study investigates the efficiency of solar tracking technology in tropical regions, focusing on Sri Lanka, which is an island located near the equator. In this study, a comparative performance analysis of a fixed-ground mounted solar PV system and a solar tracking PV system was conducted under identical system conditions and environmental conditions. The power output, operating temperature, short circuit current (Isc), open circuit voltage (Voc) data were collected continuously for 11 hours for both systems with 5-minute time intervals. The experimental results show a significant enhancement of the electrical power output of the solar tracking PV system compared to fixed-ground mounted solar PV systems. The average power output enhancement was 14.46% and the study also observed a 4.43% higher solar panel operating temperature in solar tracking PV systems. Results show that the single-axis solar tracking PV system consistently outperforms the fixed-ground mounted system, particularly in the morning and evening, due to its ability to maintain perpendicular sunlight incidence.

ASSESSING THE VIABILITY OF HIGH-CAPACITY PHOTOVOLTAIC POWER PLANTS IN DIVERSE CLIMATIC ZONES: A TECHNICAL, ECONOMIC, AND ENVIRONMENTAL ANALYSIS

Even though Turkey has a high potential in terms of solar energy, installed solar energy has a lower capacity than many European countries. With the new initiatives made in recent years, the share of solar energy among energy sources has increased. Turkey has been categorized into four different climate zones by the Turkish Standards Institute (TSE). The cities covered in this study (Antalya, Istanbul, Ankara, and Erzurum) were selected from different climatic regions by the criteria determined by TSE. High-capacity (3 MW) photovoltaic power plants using different system configurations for cities located in different climatic regions of Turkey have been analyzed in terms of technical, economic, and environmental aspects. PVSyst software was used to conduct simulations on fixed tilted (FT), horizontal single axis tracking system (HSAT), and two-axis tracking system (TAT) configurations in the study. It has been concluded that by using HSAT and TAT instead of FT, there will be an increase of 4-6% and 30-37% in annual energy production, respectively. The maximum performance rate for FT, and HSAT systems was calculated at 83.2% in Erzurum (4th region), and the lowest performance rate for TAT systems was determined at 82.3% in Antalya (1st region). The payback periods for the FT, HSAT, and TAT systems were determined to range between 2.9-4.3 years, 4-6 years, and 5.4-8.4 years, respectively. It has been concluded that there will be 41.8-64.7 ktCO<sub>2</sub>, 40.8-66.8 ktCO<sub>2</sub>, and 50.9-86.4 ktCO<sub>2</sub> fewer emissions for the FT, HSAT, and TAT systems, respectively, in 25 years of operation from an environmental point of view.

Novel flat-plate solar collector with an inclined N-S axis and relative E-W tracking absorbers and the numerical analysis of its potentials

The current flat-plate solar collectors perform best when their absorbers rotate around their axis. However, with their concentrators, reflectors, and tracking mechanisms, they take up a lot of space and are thus commercially speaking, not the best solutions. This paper proposes a novel solar collector design which employs the (relative) rotation of absorbers, but strives to combine the benefits of fixed and (absolute) tracking solar systems, i.e. volume occupancy from the former and thermal performance from the latter. The findings of our numerical analysis show that, the solar irradiance efficiency of this novel design is 20% higher than that of a fixed flat-plate collector during clear-sky days, and it is equally lower than that of an absolute tracking collector. This paper also introduces a new criterion for describing single-axis tracking solar collectors which should be included in the classifications of solar collectors. Finally, the article, which represents a continuation of our research in the field of solar energy utilization, can contribute to the future development of solar technologies and solve some of the current challenges.

Model Prototype of a Solar Tracking System Supplying Electrical Power for Sensors Used in a Natural Disaster Monitoring System

Sun is the universe main source of energy. This energy can be converted to useful electrical energy by the utilization of solar panels or photovoltaic (PV) during the daytime with the presence of suitable sun irradiation level. It is important that during the energy conversion process, suitable methods are employed to extract as much energy as possible from the PV panels. Some issues affecting PV performance are the accuracy of the panel’s orientation and tilt angle with respect to the sun position. This causes PV to operate with lower efficiency, thus generating low output power compared to its rated capacity. One of the approaches to this issue is to constantly maintain a perpendicular profile of PV panels towards the sun direction as to capture the sun energy as much as possible, thus increases the PV efficiency. To do so, the conversion system needs a tracking mechanism to help the solar panel to constantly follow the sun’s direction, enhancing the achievement of higher PV efficiency. For this reason, a model prototype has been designed and developed which consists of a dual-axis solar tracking system, with two axis movement direction from east to west and north to south by utilizing the Light Dependent Resistors (LDRs) sensors. This tracking system is developed using Arduino UNO as the microcontroller that allows the PV panel to move optimally towards the high intensity of sunlight via four LDRs and two servo motors. To analyze the PV tracker’s performance, a monitoring system is implemented using ThingSpeak platform as the Internet of Things (IoT) platform interfacing with the controller Node MCU ESP8266. This monitoring system records the data of the PV energy parameters from the sensors’ output employed in this prototype. To assess the system efficacy, the dual-axis tracking system is compared with the single-axis tracking system. The result showed that the dual-axis tracker has efficiencies of 68.46% which is higher compared to that’s of the single-axis tracker. Implementation of the real-time monitoring system has shown a practical and handy way to analyze and monitor the solar tracking system’s performance.

Impact of backtracking strategies on techno-economics of horizontal single-axis tracking solar photovoltaic power plants

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.

Aeroelastic instability mechanisms of single-axis solar trackers

Single-axis solar trackers are currently the most commonly used racking system in utility scale solar photovoltaic (PV) plants. The last decade has seen significant advances in the understanding of single-axis tracker aerodynamics after significant failures have occurred due to aerodynamic instabilities. The current study focuses on the aeroelastic mechanisms causing these divergent instabilities. The analytical background as a function of static tilt angle is presented for the different instabilities. The role of aerodynamic stiffness and aerodynamic damping are examined through rigid sectional model testing and these results are used to perform numerical stability estimates using multiple theoretical approaches. These results are compared with aeroelastic model testing of a single-axis solar tracker over a wide range of static tilt angles. These analytical, numerical, and experimental approaches are used to assess the static tilt angles governed by stiffness-driven and damping-driven aerodynamic instabilities. The small size and light weight of single-axis trackers makes them more susceptible to turbulent gusts. This aspect has been addressed in the current study through the concept of the structurally averaged wind speed and the effective gust velocity factor. Comparison to the experimental results suggests that stiffness-driven torsional instability can respond quite rapidly to the passage of turbulent gusts.

Performance of single axis tracker technology and automatic battery monitoring in solar hybrid systems

Utilization of elevation angles and azimuth angles is a very important part in maximizing solar energy into electrical energy in photovoltaic (PV). One way to maximize PV power output is to design a single axis tracker system and take into account the azimuth and elevation angles of the sun using the sun position calculator application. The single axis tracker system is set based on the position of the angle of inclination of the surface of the PV 45°, then the angle of 90° and the angle of inclination of 135°. The test results show that the single axis tracker PV system design can work based on the angle settings that have been programmed. Then the use of a battery control system to support the PV reliability system automatically cuts off electricity when the battery voltage drops below 12 V during cloudy weather conditions and excessive battery usage. The integration of the PZEM-017 module with the battery will support monitoring of battery power usage in real time. PV energy data conversion performance uses single axis tracker technology for maximum power reaching 631.72 Watt DC at 12.00 pm and the lowest power reaching 56.02 Watt DC at 6.00 pm.

The outflow characteristics of PV water lifting systems based on multiple tracking strategies

In order to clarify the problems of high failure rate, low efficiency, and low outflow rate of PV water pumping stations in pastoral areas due to large differences in resource conditions and poor equipment matching, this study uses the PV water supply model, establishes a pilot site for PV human storage water supply in pastoral areas, carries out research on the relationship between solar energy resources, water supply demand and power system of PV water pumping stations based on group observation tests in the field, and analyzes the PV system. We analyzed the relationship between different tracking operation modes and the amount of solar radiation and water supply flow, and compared the outflow characteristics of fixed type, single-axis tracking type, and double-tracking axis type, in order to explore a kind of PV water pumping station technology suitable for human storage and drinking water in pastoral areas, which can meet the water demand of pastoral water users. The research results show that the single-axis and dual-axis water lifting systems are significantly more efficient than the fixed-support water lifting system, receiving solar radiation at more than 80% of the maximum radiation throughout the day, and lifting water flow at more than 90% of the maximum discharge flow. Compared with the fixed-support PV water lifting system, the radiation of the single-axis PV water lifting system increases by 28.9%, and the daily water output increases by 43%; for the dual-axis PV water lifting system, compared with the single-axis PV water lifting system, the daily radiation of the dual-axis PV water lifting system increased by 4.8% and the daily water output increased by 3.2%; the starting radiation of the PV water lifting system was 256 W/m2.

Development of an Indoor Test-bed for Evaluation of Tracking Mechanism

Tracking systems are used in both solar photovoltaic and concentrated solar thermal power to harness solar energy. It is essential for a tracking mechanism to ensure reliability. There are possibilities of misalignment between collector and the sun, even if the sun’s position is known, which leads to noticeable energy losses. One of the reasons for this misalignment is the individual uncertainty/errors associated with different components of the tracking system. Evaluation of integrated tracking mechanism is, generally, performed on the field globally, which includes additional effects. Therefore, it is a very tedious process and time-consuming, in addition to the involved cost. Considering these aspects, this paper presents design of an indoor test-bed for evaluation of tracking mechanism under a controlled condition. The test-bed simulates the apparent sun-path, which is designed using a mathematical tool. A step-by-step approach for evaluation of a single-axis tracking mechanism is reported. However, provisions are made to evaluate even a dual-axial tracking mechanism. Experiments are performed with the considered one-axis tracking mechanism to demonstrate the applicability of such a test-bed. A comparative study shows that the test-bed indeed allows characterization of the developed one-axis tracking mechanism and its time independence. Thus, it can be safely stated that such a test bed, in future, will provide first-hand evaluation of existing and new tracking mechanism before its on-field implementation.

A horizontal single-axis tracking bracket with an adjustable tilt angle and its adaptive real-time tracking system for bifacial PV modules

An efficient photovoltaic (PV) tracking system enables solar cells to produce more energy. However, commonly-used PV tracking systems experience the following limitations: (ⅰ) they are mainly applied to single-sided PV panels; (ⅱ) they employ conventional astronomical algorithms that cannot adjust the tracking path in real time according to variable weather. In this study, a model of horizontal single-axis tracking bracket with an adjustable tilt angle (HSATBATA) is developed, and the irradiance model of moving bifacial PV modules is designed, which considers the mounting height, spacing and ground shading of PV panels. Furthermore, an adaptive real-time tracking (ARTT) algorithm is put forward to obtain the optimal tracking path for PV cells, which considers the energy consumption of tracking motors, the front and back irradiance of solar cells, cell temperature and ambient wind speed. The test results indicate that the presented ARTT algorithm enhances the energy of PV modules by 32.7 % and 7.5 %, respectively, compared to the fixed bracket and the conventional tracking algorithm. Additionally, the number of motor starts of the PV tracking system is reduced by 71.7 % compared with that of the conventional algorithm, which greatly contributes to extending the service life of PV tracking brackets and lowering the cost of electricity. Present study will help to improve the theoretical research system of PV tracking bracket construction, irradiance modeling of moving bifacial modules, and intelligent tracking algorithms.

Antenna Tracker System for Unmanned Aerial Vehicles: A Short Review

<p class="Abstract">Unmanned Aerial Vehicle (UAV) is a modern technology used to perform difficult and dangerous aerial missions that cannot be carried out by manned aerial vehicles. Ground Control Station (GCS) is a system that manages all the parameters of the UAV. GCS and UAV communicate using radio waves through telemetry, which functions to transmit and receive flight data. Antenna tracker is a device used to connect the GCS (Ground Control Station) and the UAV (Unmanned Aerial Vehicle). The antenna tracker works by performing tracking to direct the antenna towards the UAV. Nowadays, there are various forms of antennas used in telecommunication technology. Each type of antenna has its own radiation characteristics, some are directional, while others are more omnidirectional. Directional antennas are the right choice to be used with an antenna tracker. Generally, directional antennas have a narrow radiation range but a relatively long transmission distance. This paper provides a review of the state-of-the-art in antenna tracker technology for unmanned aerial vehicles (UAVs), with a focus on design, performance, and type of antenna. The study involved a literature search of various databases. The design approaches for antenna tracker systems range from simple single-axis trackers to sophisticated dual-axis trackers with pan-tilt mechanisms, and type of antenna such as helical were explored. The study concludes that antenna trackers have numerous applications in various industries, including military, agriculture, and surveying, and the demand for reliable and accurate antenna trackers is expected to continue to grow with the increasing popularity of UAVs. </p><p class="Abstract"> </p><p class="Abstract"> </p><p class="Keywords"> </p>

Theoretical and experimental investigation of the glass tube solar collector with inclined N-S axis and relative E-W single-axis tracking flat absorber

This paper presents a new solar collector design that combines flat absorber plates and glass tubes with a compacted automatic time-controlled (E–W) single-axis tracking mechanism. The mentioned design incorporates the advantages of the single-axis tracking system with a relatively small increase in the solar collector dimensions. According to it, a mathematical model was formed, and the test sample was fabricated. Using a bespoke test rig, the experimental investigation was carried out by simultaneously measuring the thermal performances of the solar collector in question and the flat plate solar collector with the same inclined position and absorber material. The experimental results (from July 15 to October 15, 2021) showed that compared to a reference collector, the new solar collector’s average daily specific useful heat was higher in the range of 14–23%, and the overall thermal efficiency was higher in the range of 9.7–17.9%. Using the obtained experimental and simulation data, the mathematical model was verified within an average deviation of 5.67%. Despite the partial reduction of the useful heat due to the mutual shading of absorbers, the mentioned solar collector shows promising results along with a compact design. We propose that this device will present promising opportunities in future applications.

Initial Design of Dual Axis Solar Tracking System with the Addition of Camera and Cooling System

Solar panels have been widely used to determine solar energy as an electrical energy generator. However, the installation of solar panels is still static, so it cannot follow the sun's movement optimally. Solar panels with dual-axis tracking have a wide range in the tracking process. The range that can be tracked by dual-axis tracking is azimuth angle and altitude, while single-axis tracking can only choose one side of the angle. In this study, the initial design of the dual-axis solar tracking system was made with cameras and cooling systems combined with heatsinks and tubular pipes. The design made is in the form of a CAD design using SolidWorks software, and the design made will be used for subsequent research, In this solar panel, the fill factor results are 0.634, and the efficiency of solar panels is 17.53% with the addition of a cooling system which can reduce the temperature of solar panels is expected to be higher efficiency. The study results were obtained in the design of a solar tracker with the addition of a cooling system that will later reduce the temperature and increase the efficiency of solar panel about 0.38% every 1℃ decreases of temperature.

Comparing solar inverter design rules to subhourly solar resource simulations

The input of a solar inverter depends on multiple factors: the solar resource, weather conditions, and control strategies. Traditional design calculations specify the maximum current either as 125% of the rated module current or as the maximum 3 h average current from hourly simulations over a typical year, neglecting extreme irradiance conditions: cloud enhancement events that usually last minutes. Inverter power-limiting control strategies usually prevent extreme events to cause strong currents at the inverter, but in some cases, they can fail, leading to high currents. In this study, we aim to report how frequent and strong these high currents could be. We use 10 years of 1 min data from seven stations across the United States to estimate the photovoltaic string output through modeling the short-circuit current Isc, and the maximum-power point current Imp, and compare them to traditional inverter design values. We consider different configurations: minutely to hourly resolution; 5 min to 3 h averaging time intervals; monofacial and bifacial modules (with a case of enhanced albedo); and 3 fixed-tilt angles and horizontal single-axis tracking. The bifacial modules with enhanced albedo lead to the highest currents for 1 min data, exceeding 3 h averages by 53% for Isc and 38% for Imp. The 3 h average maxima surpass the conservative 125% design rule for bifacial modules. Inverter ratings at either a 200% of the rated current or 1.55 times the 3 h maximum could withstand all events regardless of control strategies. In summary, for some locations it is prudent to compare current design rules to subhourly simulations to guarantee the fault-free operation of solar PV plants.