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Solar Slewing Drive
- Nov 19, 2018 -

A solar tracker is a device that orients a payload toward the Sun. Payloads are usually solar panels, parabolic troughs, fresnel reflectors, lenses or the mirrors of a heliostat.

As a clean and pollution-free energy source, solar energy has a very broad development prospect and has become a green energy source developed by various countries. However, solar energy has problems such as low density, intermittent, and the direction and intensity of light constantly changing with time. Most of the traditional solar panels are fixedly installed, that is, the panels are fixed at an angle and do not change with the position of the sun, which seriously affects the photoelectric conversion efficiency. It is estimated that if the photoelectric system has a deviation of 25 degrees from the angle of the solar rays, The PV array output power is reduced by about 10% due to the reduced radiant energy at normal incidence. Spring, summer, autumn and winter all year round, day to night, the sun's rise and fall, the angle of the sun's rays, the moment is changing. Therefore, how to change the angle of the battery panel with the angle of light to improve the PV conversion rate, this is the theme of our discussion, single-axis tracking and dual-axis tracking system.


Single-axis tracking: As the name implies, there is only one axis of rotation to change the position angle of the panel to maximize the solar light intensity perpendicular to the panel's light intensity, thereby increasing the PV conversion rate.
Single-axis tracking can be divided into horizontal single-axis tracking, tilt single-axis tracking, and vertical single-axis tracking according to the orientation of the rotating shaft. According to the type of motion actuators and the type of transmission system, it can be divided into: the type of electric push rod unit structure, the type of electric push rod linkage structure, the type of rotary worm gear drive unit structure, and the type of rotary worm gear drive linkage structure.

Horizontal single axis trackers slewing drive 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.

A vertical axis tracker slewing drive pivots only about a vertical axle, with the panels either vertical, at a fixed, adjustable, or tracked elevation angle. Such trackers with fixed or (seasonally) adjustable angles are suitable for high latitudes, where the apparent solar path is not especially high, but which leads to long days in summer, with the Sun traveling through a long arc.

Dual axis trackers are typically used in smaller residential installations and locations with very high government feed in tariffs.

Comprehensive comparison of horizontal single-axis tracking, tilted single-axis tracking, and dual-axis tracking structure maintenance features, as well as power generation increase rate, is generally considered to be less than 30 degrees latitude, suitable for horizontal single-axis tracking systems, or tilted single-axis tracking systems. A zonal above 35 degrees is suitable for a two-axis tracking system.