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The design and location of solar energy technologies are based chiefly on the availability of solar resource. Specialized measurement equipment and solar resource assessment techniques are mandatory in order to identify appropriate locations for deploying solar systems while minimizing risk and increasing the return rate of the site. These needs have given the scientific community a motivation to design highly reliable and cost-competitive sensors. This work presents a novel methodology to estimate solar irradiance components using a low-cost sky-imager system. Captured images are processed to correct the spherical aberration of the dome and to achieve a pixel-radiance model, allowing each pixel of the image to be considered as an individual source of irradiation. The performance of the proposed model is analyzed and compared in four different weather scenarios against a secondary standard solarimetric station, obtaining a normalized mean bias error for direct normal irradiance, global horizontal irradiance and diffuse horizontal irradiance of 4.53%, −6.55% and 19.62% for a sunny day, 0.79%, −6.13% and 7.00% for a partially sunny day, 1.96%, −6.58% and −0.73% for a partially cloudy day, 100%, −10.48% and −0.65% for a cloudy day, respectively. According to the experimental results, the system stands out for its performance, easy setup, low-cost components and a robust estimation in all possible weather scenarios.

It is well known that concentrating solar power and concentrating photovoltaic technologies require high accuracy and high precision solar tracking systems in order to achieve greater energy conversion efficiency. The required tracking precision depends primarily on the acceptance angle of the system, which is generally tenths of a degree. Control algorithms applied to active solar tracking systems command and manipulate the electrical signals to the actuators, usually electric motors, with the goal of achieving accurate and precise solar tracking. In addition, a solar tracking algorithms system must provide robustness against disturbances, and it should operate with minimum energy consumption. In this work, a systematic review of the control algorithms implemented in active solar tracking systems is presented. These algorithms are classified according to three solar tracking control strategies: open-loop, closed-loop and combined open- and closed-loop schemes herein called hybrid-loop. Their working principles as well as the main advantages and disadvantages of each strategy are analyzed. It is concluded that the most widely used solar tracking control strategy is closed-loop, representing 54.39% of all the publications consulted. On–off, fuzzy logic, proportional-integral-derivative and proportional-integral are the control algorithms most applied in active solar tracking systems, representing 57.02%, 10.53%, 6.14% and 4.39%, respectively.

The automobile lateral-view mirrors are the most important visual support for driver safety; therefore, it is important they have robust quality control. Typically, the distortion of a lateral-view mirror is measured using the JIS-D-5705 standard; however, this methodology requires an expert person to perform the measurements and calculations manually, which can induce measurement errors. In this work, a semi-automatic distortion calculation method based on image processing is presented. Distortion calculations of five commercial mirrors from different manufacturers were performed, and a comparative study was carried out between the JIS-D-5705 standard and the proposed method. Experimental results performed according to the JIS-D-5705 standard showed that all mirrors have a distortion lower than 5%, indicating that all meet the standard. On the other hand, the proposed method was able to detect that one of the mirrors presented an important distortion, which was not detected by the methodology proposed in the standard; therefore, that mirror should not meet the standard. Then, it was possible to conclude that the proposed distortion calculation method, based on image processing, has higher robustness and precision than the standard. In addition, an appropriate and effective behavior against changes in scale, resolution, and, unlike the standard, against changes in image rotation was also shown.

Solar energy is considered as one of the most important sources of renewable energy due to the possibility of being converted into electrical power, which could result in a feasible approach to global energy problems. Concentrated Solar Power (CSP) and High Concentration Photovoltaics (HCPV) systems present an alternative by the use of cost-efficient concentrating optics. However, these systems require a high-precision solar tracking system, allowing to stay perpendicular to the sun rays in order to achieve its correct functioning. In this work, a methodology for the detection and monitoring of the apparent movement of the sun through a passive image acquisition system is presented. The setup operates by processing sky dome images to find the solar-center. The development cost of this device is relatively low, it does not require articulated elements, can detect the presence of clouds, and could be compatible with multiple CSP systems. Preliminary results of a two-axis solar tracking by locating position of the sun in the sky with the proposed system are depicted.

The present work focuses on the analysis of a two-axis pedestal-type solar tracking system controlled by a Proportional-Integral-Derivative (PID) control law plus feedforward applied to the motors that drive the tracking system. The implementation of a solar positioning algorithm is performed to calculate the trajectories of the solar tracking system to track the movement of the sun. These trajectories are applied as desired trajectories to the PID control loops controlling the motors. Results of real-time experiments are presented, and the energy consumption of the motors is analyzed.

In this work the development of a low-cost solar sensor capable of locating the position of the sun through photosensors is presented. In addition, the sensor is integrated with the instrumentation to provide the data for a solar position algorithm. As preliminary results, we present the methodology followed for the development of the sensor, as well as the theoretical characterization carried out through the Tonatiuh software.

Solar resource assessment is fundamental to reduce the risk in selecting the solar power-plants&rsquo, location, also for designing the appropriate solar-energy conversion technology and operating new sources of solar-power generation. Having a reliable methodology for solar irradiance forecasting allows accurately identifying variations in the plant energy production and, as a consequence, determining improvements in energy supply strategies. A new trend for solar resource assessment is based on the analysis of the sky dynamics by processing a set of images of the sky dome. In this paper, a methodology for processing the sky dome images to obtain the position of the Sun is presented, this parameter is relevant to compute the solar irradiance implemented in solar resource assessment. This methodology is based on the implementation of several techniques in order to achieve a combined, fast, and robust detection system for the Sun position regardless of the conditions of the sky, which is a complex task due to the variability of the sky dynamics. Identifying the correct position of the Sun is a critical parameter to project whether, in the presence of clouds, the occlusion of the Sun is occurring, which is essential in short-term solar resource assessment, the so-called irradiance nowcasting. The experimental results confirm that the proposed methodology performs well in the detection of the position of the Sun not only in a clear-sky day, but also in a cloudy one. The proposed methodology is also a reliable tool to cover the dynamics of the sky.