Solar tracker technics

See also our  solar photovoltaic trackers in the section PRODUCT AND KITS

	Solar tracker with post Max power per each tracker: 3.2 kWp Max power per m2 of covered surface : 135 Wp/m2 Best orientation : toward south (160-200°)	Ask for estimate  From 2953€ each 1144€/kWp Photovoltaic material not included
	Solar tracker for roof Max power per each tracker: 1.8 kWp Max power per m2 of covered surface : 90 Wp/m2 Best orientation : toward south (160-200°)	Ask for estimate  From 1086€/kWp Photovoltaic material not included

SOLAR TRACKER

A solar tracker is a mechanical device meant to angle a photovoltaic or solar panel or a solar concentrator towards the ray of the sun.

The main purpose of a tracker is to maximize the efficiency of the device hosted on board.

CLASSIFICATION

According to their structural characteristics, the tracker are divided according to:

• Degrees of freedom;

• Power supplied to the shifting mechanism;

• Type of electronic control.

 TYPE OF TRACKING

 TILT TRACKERS

Tilt trackers (or pitching) are the simplest to make, they rotate around the east-west axis. the panel is raised or lowered manually (usually twice a year) toward the horizon, so that the angle in relation to the ground is statistically optimal also according to the season; these kind of trackers increase the production less than 10%, so that a servomechanism is rarely justified.

LURCH TRACKERS

Lurch trackers are meant to follow the sun across the sky in its daily journey, regardless of the season. In this cas their rotation axis is north-south, while the height of the sun above the horizon is ignored. 

These trackers are particularly suitable for low-latitude countries (Italy included, especially the south), where the sun's path is on the average wider during the year. The rotation required for these structures is wider than the tilt ones, sometimes going up to ±60°. These trackers make seem each row of photovoltaic modules like a spit angled toward the equator.

An advanced feature of these trackers is called backtracking, and it solves the problem of the shades caused at dawn and sunset by the rows of the potovoltaic modules raising up toward the horizon. With this technique the servomechanisms angle the modules toward the sun rays only during the central part of the day, while they reverse the tracking close to dawn and sunset. The night-time orientation of a backtracking photovoltaic field is perfectly horizontal to the ground, and after dawn the misalignement of the orthogonal axis of the modules relative to the sun rays is gradually reduced as the shadows allow it. Before sunset a similar but contrariwise procedure is performed, bringing back the photovoltaic field into an horizontal position for the night-time.

AZIMUTH TRACKERS

Azimuth tracker (or yaw) have one degree of freedom on a zenith-nadir axis. To get this, the panel is mounted on a rotating power-assisted basis, coplanar to the ground. The result is the increase of electricity production of about 25%.

TRACKERS WITH TWO DEGREES OF FREEDOM

More advanced tracker have two degrees of freedom, which are meant to perfectly align in real-time the panels' orthogonal axis toward the sun rays. With these trackers the increase in electricity production reaches about 35%-40%, but they have a more complex design.

Advantages of photovoltaic solar trackers

Trackers' servomechanisms are not too stressed, but by their nature they are  subject to harsh weather conditions for at least twenty years. For this reason they must be made with care and with the utmost attention to corrosion and to the guarantee of the actuator which moves the photovoltaic field. For this reason it is very important to request a high guarantee on the engine.

 Routine maintenance is simple, and in a photovoltaic field is less affected by the dust on the modules' surface, thanks to the average angle of incidence of solar rays.