Fish-eye camera and image processing for commanding a solar tracker

Abstract

The design and implementation of a solar tracker based on panoramic images captured by a fisheye camera are proposed. Such images receive a digital treatment to estimate the sun azimuth and the elevation angles. These angles are fed to a microcontroller, handling an accelerometer with a gyroscope, that positions the solar tracker to the angle of solar elevation and a compass to set the azimuth angle concerning the north, either magnetic or geographic. The proposed system works satisfactorily to guide the solar tracker regardless of whether it is a sunny or cloudy day.

Pilot Low-Cost Concentrating Solar Power Systems Deployment in Sub-Saharan Africa: A Case Study of Implementation Challenges

“…Tracking mechanisms can also be classified into open-loop control and closed-loop control. In an open-loop control passive tracking system, the tracking system uses mathematical formulae to predict the Sun's movement without requiring any feedback [37]. The controller computes the equation into the tracking system using only the current state and the algorithm of the system and without using feedback to determine whether the output is the desired result.…”

“…Moreover, the lack of feedback increases the complexity of the control system and makes the system less accurate. On the other hand, a passive closed-loop system [37] requires feedback from the Sun's position and often employs a pair of opposing solar-powered actuators that are positioned to receive equal solar radiation only when the mirrors point directly at the Sun. Misalignment with the solar vector causes negative feedback that serves to continuously track the Sun.…”

Characterization of cadmium sulfide light dependent resistors sensors for optical solar trackers

“…The active sun trackers are divided into three other systems: − Sensorless sun trackers: this type of sun trackers uses astronomic equations that can predicts the position of the sun depending on date-time and geographic location, it have the advantage of being independent of weather conditions, but it requires feedback from motor's encoders in order to know its position, and needs an initial precise installation and calibration with Nord pole axis [14]. − Sensored sun trackers: this type of sun trackers is based exclusively on sensors, it usually use electrooptical sensors such as light dependent resistors [15], [16], photodiodes [17], cameras [18]- [20], it have the advantages of do not needs a feedback from motors, don't needs an initial alignment with the Nord pole and it is totally independent of the date-time and the geographic location of the system, but it is weather sensitive and miss easily the sun position during cloudy days.…”

Hemispherical Photographs: A Review of Acquisition Methods and Applications in the Context of Urban Energy and Environment Assessments

“…As a result of the excellent progress and promising results achieved by the plant ecology community, these photographs began to gain popularity in other fields of research and development. Examples include nowcasting (using cameras with a spherical mirror [20], cameras equipped with fisheye lenses [21,22], mobile cameras [23], and security cameras [24]) and forecasting (using camera arrays [25], cameras with a spherical mirror [26], and cameras mounted with fisheye lenses such as security cameras [27,28], network cameras [29], high-resolution commercial cameras [30,31], custom-built cameras [32], and waterproof cameras [33]) to assess solar radiation by detecting cloud movements in open areas; determining the location of the sun for solar photovoltaic (PV) and solar concentrator tracking applications (such as finding the location of the sun [34]; optimizing sun tracking on cloudy days [35]; developing single-axis [36] and dual-axis sun trackers [37,38]); monitoring and controlling the solar flux in power plants [39,40]; measuring the angular distribution of light from solar reflectors [41][42][43]; estimating aerosol characteristics [44]; and determining solar absorptance for the clothed human body [45,46].…”