Green Technology

Enhancing Solar Energy Capture and Efficiency

Advances in solar tracking systems have increased energy capture and efficiency. The new technology has many advantages, including cost reductions, increased reliability, and improved utilization rates. Solar tracking systems are typically categorized into three main types:

* Fixed-tilt
* Single-axis trackers for PV arrays or exposed collectors
* Dual-axis trackers for PV arrays and buried collectors. The choice will depend on site-specific conditions.

Fixed Tilt Systems

A fixed-tilt system is a design that uses an optical sensor on the roof of a building to detect tilt changes caused by the sun’s position in space over time. The solar panels are mounted on a fixed structure. The axis of the solar panels is tilted at a fixed angle to the incoming solar rays. When the sun rises and sets on the horizon, it no longer makes contact with the panels resulting in lost energy. Tracking systems can improve energy capture potential by 20% or more. It is best suited in places with large areas of flat terrain, such as the Sahara Desert in Africa. Fixed-tilt tracking systems are cost-effective and can be installed on small or mid-size installations.

Single Axis Trackers

A single-axis tracker is a solar system that uses a single optical sensor to detect angle changes due to the solar panels’ tilt on a fixed axis. This type of device has many applications, such as agricultural applications, where it can track the movement of livestock or crops. It is also used for monitoring roof-mounted solar panels by calculating the distance they have moved during a particular day. In the solar energy industry, single-axis trackers rotate using a design optimized for high performance. The tracker’s orientation follows the sun throughout the day on a single fixed axis, increasing its efficiency by using available sunlight.

Dual Axis Tracking Systems

A dual-axis tracking system is typically used for large power plants. These systems are designed to operate on two axes of rotation to maximize the use of available sunlight. A dual-axis tracker uses two optical sensors that detect angles and rotate along two axes based on the data collected from both sensors. A single-axis tracker with two axes of rotation will be called a “bi-axial tracker.” The sun’s position moves in the sky as the day progresses, which requires tracking systems to rotate on two horizontal and vertical axes. During sunrise and sunset, the dual-axis tracking system automatically adjusts its angles to collect sunlight. It enhances energy efficiency by optimizing the output from solar cells on a sunny day compared with a cloudy one. A dual-axis tracker provides increased energy use due to an array in constant motion. It is beneficial on cloudy days because it can accommodate moving clouds with its dual axes while increasing overall power output because each axis is optimized separately. It is necessary to ensure the dual-axis tracking system has adequate space to move the solar panels into different positions.

The main components of a solar tracking system include:

A solar tracking system requires an appropriate mounting location on the array that can withstand extreme temperatures, wind load and high wind speeds. Typical outdoor array mounting locations include rooftops, hillsides, reservoirs and power plants. The type of mounting location will determine the functions of the tracker. For example, if there is a large amount of wind in a particular area, it might be feasible to mount a solar tracker on top of a building or near an open field with no fixed mounts. The tracker must be able to be inset into the ground and resist corrosion due to weather.

To determine the best location for a tracker, it is essential to consider the site’s characteristics, including wind speed, ambient temperature, snow load, and solar radiation angle. Generally speaking, tracking systems are easier to install at a location with intense solar energy availability but lower ambient temperatures.

Various mechanical systems can be used depending on the amount of automation needed in a system and local site conditions regarding wind load, snow load and seismic activity. Automated systems can be categorized as follows:

To determine the best type of tracker for a particular application, the following steps should be considered:

Mounting type, field size and structure are the essential criteria to decide solar tracker.

The tilt angle of a fixed tilt system will remain constant throughout the day. Solar trackers use motors to shift their axis to follow the sun throughout the day. When a single-axis tracker can use horizontal and vertical axes, it is called a bi-axis tracking system. The tracking system will track the sun throughout the day and adjust its angle to follow the sun’s movement. Trackers contain sensors that detect the tilt angle of solar panels, which induces the motor to rotate in either a vertical or horizontal direction. Solar panels are mounted on a fixed structure; therefore, it is necessary to determine what happens when the solar panel moves about an improved system.

There are many different types of tilt sensors used by solar tracker systems. There are optical sensors that can detect motion, and there are position sensors (mechanical, electrical or pneumatic) that can be used instead of an optical sensor if action is not required.

Solar tracking systems are useful in applications such as:

Systems using solar tracking technologies have the potential to have an energy efficiency increase of approximately 20% on average. It can be more significant in applications that require precise energy output, such as power plants. When used on a utility power plant, a solar tracker system can tilt the solar panels 30-50 degrees depending on the available sunlight during the day. For most large industrial installations, this will result in more efficient use of available energy on sunny days compared with days with less sunlight. Customizations can be achieved by adjusting the tilt angle of each axis individually and using multiple sensors for closed-loop operation for increased accuracy and efficiency.

Applications for solar trackers used in the electric power sector include:

Solar tracking systems are helpful for extensive facilities that have large arrays. Individual utilities and larger utility companies can use tracking systems in France, Spain, Germany and Italy. There is a potential to create a power plant in Africa that uses solar collectors and wind turbines instead of coal. Solar trackers can provide electricity at lower costs than fossil fuel-based power plants. Due to the automation aspect of solar trackers, solar tracking can utilize an existing cable laying and mounting infrastructure.

One type of solar tracker currently available commercially is the dual-axis tracker. A dual-axis tracking system can move a solar panel on both the horizontal and vertical axis. A dual-axis tracker can follow the sun’s movement daily when tracking the sun. By adjusting both axes, it is possible to position panels so they can capture sunlight even on cloudy days. This type of system’s energy output and efficiency will be heightened because it uses two separate motors for each axis instead of one motor for one axis and another motor for another.

A double-axis tracker is another tracking system that uses two axes to align a solar array with the sun. One axis will be aligned horizontally and the other vertically, where the variety will rotate around both axes to follow the sun throughout the day. This kind of system has been used on more than 1,600 timeshare residences. A double-axis tracking system is beneficial because it provides additional power on days with low sunlight intensity or insufficient direct sunlight. The main advantage of a double-axis tracking system is its ability to use horizontal and vertical axes for tracking, whereas most trackers use only one or two axes.