Solar tracker
[1][2] As the pricing, reliability, and performance of single-axis trackers have improved, the systems have been installed in an increasing percentage of utility-scale projects.
The optics in concentrated solar applications accept the direct component of sunlight light and therefore must be oriented appropriately to collect energy.
[9][10] The Sun travels through 360° east to west per day, but from the perspective of any fixed location, the visible portion is 180° during an average half-day period (more in summer, slightly less in spring and fall, and significantly less in winter).
A solar panel in a fixed orientation between the dawn and sunset extremes will see a motion of 75° to either side, and thus, according to the table above, will lose over 75% of the energy in the morning and evening.
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.
A recent review of actual production statistics from southern Ontario suggested the difference was about 4% in total, which was far less than the added costs of the dual-axis systems.
Alternatively, for example in an area where cloud cover on average builds up during the day, there can be particular benefits in collecting morning sun.
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.
The underlying power conversion efficiency of a photovoltaic cell has a major influence on the end result, regardless of whether tracking is employed.
Therefore, trackers can deliver additional benefit by collecting early morning and winter energy when the cells are operating at their highest efficiency.
Thus the primary benefit of a tracking system is to collect solar energy for the longest period of the day, and with the most accurate alignment as the Sun's position shifts with the seasons.
The sun-tracking system controlling the direction of the panels operates automatically according to the time of year, changing position by means of ropes attached to buoys.
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.
The optics in CPV modules accept the direct component of the incoming light and therefore must be oriented appropriately to maximize the energy collected.
It works on the same principle as HSAT, keeping the axis of tube horizontal in north-south line and rotates the solar modules from east to west throughout the day.
Dual-axis trackers allow for optimum solar energy levels due to their ability to follow the Sun vertically and horizontally.
The main advantage of this arrangement is the weight of the array is distributed over a portion of the ring, as opposed to the single loading point of the pole in the TTDAT.
For a small (amateur/enthusiast) construction, the criteria that must be met include economy, stability of end product against elemental hazards, ease of handling materials, and joinery.
[28] The selection of tracker type is dependent on many factors including installation size, electric rates, government incentives, land constraints, latitude, and local weather.
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.
This device uses multiple mirrors in a horizontal plane to reflect sunlight upward to a high-temperature system requiring concentrated solar power.
A multiple-mirror reflective system combined with a central power tower was employed at the Sierra SunTower, located in Lancaster, California.
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.
[citation needed] Counter-rotating slewing drives sandwiching a fixed-angle support can be applied to create a "multi-axis" tracking method which eliminates rotation relative to longitudinal alignment.
Active two-axis trackers are also used to orient heliostats – movable mirrors that reflect sunlight toward the absorber of a central power station.
Light-sensing trackers typically have two or more photosensors, such as photodiodes, configured differentially so that they output a null when receiving the same light flux.
In Freiburg im Breisgau, Germany, Rolf Disch built the Heliotrop in 1996, a residential building that is rotating with the sun and has an additional dual-axis photovoltaic sail on the roof.
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.
