What is solar tracking?

Solar tracking is where the solar panels follow the sun’s path through the sky. Tracking systems capitulates considerably more energy than stationary systems. The energy from the sun can be either diffuse or direct radiation. Direct radiation is sunlight that comes directly from the sun, and diffuse radiation is the light that’s spread throughout the atmosphere. The “direct beam” that carries about 90% of the solar energy, and the “diffuse sunlight” that carries what is left – the diffuse portion is the blue sky on a clear day and is a larger proportion of the total on cloudy days. When you are inside the house you are not a subject to direct radiation, but you can still see because diffuse radiation reaches you. Most solar systems (PV) power systems use fixed panels. On a clear day as low as 10% of the sun rays are diffuse radiation, Solar systems needs as much as it can get direct radiation in order to be most productive.

Horizontal single axis trackers are typically used for large distributed generation projects and utility scale projects. The combination of energy improvement and lower product cost and lower installation complexity results in compelling economics in large deployments. In addition the strong afternoon performance is particularly desirable for large grid-tied photovoltaic systems so that production will match the peak demand time. Horizontal single axis trackers also add a substantial amount of productivity during the spring and summer seasons when the Sun is high in the sky. The inherent robustness of their supporting structure and the simplicity of the mechanism also result in high reliability which keeps maintenance costs low. Since the panels are horizontal, they can be compactly placed on the axle tube without danger of self-shading and are also readily accessible for cleaning.

The purpose of a tracking mechanism is to follow the Sun as it moves across the sky. In the following sections, in which each of the main factors are described in a little more detail, the complex path of the Sun is simplified by considering its daily east-west motion separately from its yearly north-south variation with the seasons of the year.

A tracker that accounts for both the daily and seasonal motions is known as a dual-axis tracker. Generally speaking, the losses due to seasonal angle changes is complicated by changes in the length of the day, increasing collection in the summer in northern or southern latitudes. This biases collection toward the summer, so if the panels are tilted closer to the average summer angles, the total yearly losses are reduced compared to a system tilted at the spring/fall solstice angle (which is the same as the site’s latitude).

As described later, the economical balance between cost of panel and tracker is not trivial. The steep drop in cost for solar panels in the early 2010s made it more challenging to find a sensible solution. As can be seen in the attached media files, most constructions use industrial and/or heavy materials unsuitable for small or craft workshops. Even commercial offers like “Complete-Kit-1KW-Single-Axis-Solar-Panel-Tracking-System-Linear-Actuator-Electric-Controller-For-Sunlight-Solar/1279440_2037007138” have rather unsuitable solutions (a big rock) for stabilisation. For a small(amateur/enthusiast) construction following criteria have to be met: economy, stability of end product against elemental hazards, ease of handling materials and joinery

Benefits of Tracking System

With a fixed solar system, it does not reaches it maximum until the sun is directly overhead, A tracking system move from east to west   following the rise of the sun without loss and quickly reaching the area of little variation of power for several hours while the stationary systems only briefly reach their maximum power around midday.

Tracking can also cause shading problems. As the panels move during the course of the day, it is possible that, if the panels are located too close to one another, they may shade one another due to profile angle effects. As an example, if you have several panels in a row from east to west, there will be no shading during solar noon. But in the afternoon, panels could be shaded by their west neighboring panel if they are sufficiently close. This means that panels must be spaced sufficiently far to prevent shading in systems with tracking, which can reduce the available power from a given area during the peak Sun hours. This is not a big problem if there is sufficient land area to widely space the panels. But it will reduce output during certain hours of the day (i.e. around solar noon) compared to a fixed array.

Due to the tilt of the Earth’s axis, the Sun also moves through 46 degrees north and south during a year. The same set of panels set at the midpoint between the two local extremes will thus see the Sun move 23 degrees on either side. Thus according to the above table, an optimally aligned single-axis tracker (see polar aligned tracker below) will only lose 8.3% at the summer and winter seasonal extremes, or around 5% averaged over a year. Conversely a vertically or horizontally aligned single-axis tracker will lose considerably more as a result of these seasonal variations in the Sun’s path. For example, a vertical tracker at a site at 60° latitude will lose up to 40% of the available energy in summer, while a horizontal tracker located at 25° latitude will lose up to 33% in winter.

Are Solar Tracking Systems Worth It

Even though the sun may not feel particularly hot in the early mornings or during the winter months, the diagonal path through the atmosphere has a less than expected impact on the solar intensity. Even when the sun is only 15° above the horizon the solar intensity can be around 60% of its maximum value, around 50% at 10° and 25% at only 5° above the horizon. Therefore, trackers can deliver benefit by collecting the significant energy available when the Sun is close to the horizon.

Still in its infancy, programmable tracking systems are being developed with software to not only rotate the reflector to maintain maximum exposure to the sun, but also to control cooking time and desired temperatures. One example of an auto tracking and monitoring system is the Solar Cue system. Another is the Raspberry Pi: Solar Matic, but there are a range of such programmable sun trackers.

Solar trackers can be built using a “floating” foundation, which sits on the ground without the need for invasive concrete foundations. Instead of placing the tracker on concrete foundations, the tracker is placed on a gravel pan that can be filled with a variety of materials, such as sand or gravel, to secure the tracker to the ground. These “floating” trackers can sustain the same wind load as a traditional fixed mounted tracker. The use of floating trackers increases the number of potential sites for commercial solar projects since they can be placed on top of capped landfills or in areas where excavated foundations are not feasible

Two Types of Trackers

There are many ways to describe the kind of motion and angles a solar tracker can be accomplished. There are two categories, single-axis, and dual-axis. A single-axis tracker can move east to west, but its angle on the north-south plane is stable. A dual-axis tracker can adjust itself in any angle. A single-axis tracker, a dual-axis tracker is able of facing the sun direct at any time of the day.


ECO-WORTHY 400 Watts Complete Single Axis Solar Tracking System Solar Sunlight Tracker Kits

  • Complete solar tracking kits: 4pcs 100w solar panel & 1pc 18″ linear actuator & 1pc solar tracking controller & all frame mounting brackets.
  • The system can move towards East-West direction & South-North direction, thus it has the function of dual axis solar tracking system.
  • Solar mounting arms are all made from Aluminum 6061.
  • Mounting pole is made from galvanized iron tube.
  • Increase power output up to 35% compare to standby solar bracket.

Solar tracker systems are rising in recognition; most people do not understand the complete benefits and likely drawbacks of the system. Trackers solutions are a more advanced technology for mounting photovoltaic panels. Stationary mounts, which hold panels in a fixed position, can have their output compromised when the sun is not directly overhead. Solar trackers automatically move to track the sun across the sky, thus maximizing output.

Advantages:

  • Trackers generate more electricity than their stationary panels because of direct exposure to solar rays. This increase can be as much as 10 to 25% depending on the geographic location of the tracking system.
  • There are many different kinds of solar trackers, such as single-axis and dual-axis trackers
  • Solar trackers generate more electricity in roughly the same amount of space needed for fixed-tilt systems, making them ideal for optimizing land usage.
  • Advancements in technology and reliability in electronics and mechanics have drastically reduced long-term maintenance concerns for tracking systems.

Disadvantages:

  • Solar trackers are slightly more expensive than a stationary system, due to technology and moving parts necessary for tracking.
  • There is higher maintenance required than a traditional fixed system
  • Trackers are a more complex system than fixed racking; more preparation is needed, including additional trenching for wiring.
  • These systems are more complex and thus are seen as a higher risk from a financier’s viewpoint.
  • Solar trackers are generally designed for climates with little to no snow making them a more viable solution in warmer climates. Fixed tracking handles harsher ecological conditions more easily than tracking systems.
  • Fixed tracking systems offer more field adjustability than single-axis tracking systems.

Solar Panel Tracking Vs Stationary

Active trackers use motors and gear trains to perform solar tracking. They can use microprocessors and sensors, date and time-based algorithms, or a combination of both to detect the position of the sun. In order to control and manage the movement of these massive structures special slewing drives are designed and rigorously tested. The technologies used to direct the tracker are constantly evolving and recent developments at Google and Eternegy have included the use of wire-ropes and winches to replace some of the more costly and more fragile components.

The axis of rotation for vertical single axis trackers is vertical with respect to the ground. These trackers rotate from East to West over the course of the day. Such trackers are more effective at high latitudes than are horizontal axis trackers. Field layouts must consider shading to avoid unnecessary energy losses and to optimize land utilization. Also optimization for dense packing is limited due to the nature of the shading over the course of a year. Vertical single axis trackers typically have the face of the module oriented at an angle with respect to the axis of rotation. As a module tracks, it sweeps a cone that is rotationally symmetric around the axis of rotation.
The physics behind CPV optics requires that tracking accuracy increase as the systems concentration ratio increases. However, for a given concentration, nonimaging optics provide the widest possible acceptance angles, which may be used to reduce tracking accuracy.

Arctech Solar is one of the world’s largest manufacturers and solution provider of solar tracking and racking systems for utilities, commercial, industrial and residential projects.

Solar trackers significantly boost the amount of electricity through a constant orientation of the PV panels towards the sun for the whole day. There is no other single balance-of-system (BOS) component that can boost a PV system’s performance like a tracker. That is why global solar tracker market is expected to grow at a CAGR of 12% from 2014 to 2020 and reach 7 GW by 2020.

Arctech trackers are solutions to high return on investment and make solar projects economically profitable under cost pressure. In particularly, Arctech redundancy horizontal single-axis trackers are the most attractive solutions in terms of profitability and reliability. The standard horizontal single-axis tracker is most suitable for relatively low latitude while horizontal single-axis tracker with tilted modules and tilt single-axis tracker are normally used for higher latitude.

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