Leading supplier of turnkey photovoltaic systems in Italy, the EAR Group Company relies on incremental encoders and inductive proximity sensors from SICK to optimise energy yield from their solar panels.
EAR Group’s plant in the Italian town of Cerbera covering an area of 30,000m² consists of 93 solar fields, each with 33 solar panels. DC-AC inverters convert the direct current generated into alternating current on location. The overall output of the facility is 700 kWp.
Trackers have been installed on the solar panels to enable them to follow the sun’s path automatically, resulting in a substantially higher energy yield than when using rigid panels. The repositioning motion is controlled by the trackers that change the alignment of the photovoltaic collectors at varying minute intervals.
The trackers feature two motors with one aligning the panel to the position of the sun and the other providing extremely precise tracking of the panels during the day corresponding to the path of the sun. Each of these current deviations of a solar panel in relation to the alignment due south is called azimuth.
The trackers ensure optimum energy yield, which may be at up to 40% higher than that of fixed panels.
Both tracker motors are equipped with DFS60 incremental encoders featuring through hollow shafts. Mechanical integration for tilt tracking is achieved by mounting the encoder directly on a motor-driven rotating mechanism while the rotating motion is converted by means of a linear guideway into linear travel for the solar field.
The azimuth tracking is controlled by an encoder installed in a separate casing on the concrete foundation of the solar field.
According to Gianlucca Narducci, Technical Director of EAR Group, the SICK sensors were selected for the application due to their high resolution and precise tracking of the panels in addition to their ruggedness in outdoor use as well as compact, easy-to-integrate design.
The DFS60 incremental encoders guarantee maximum availability in all kinds of weather and temperatures between –30°C and +100°C thanks to features such as a metal code disk, dual shaft bearings, high enclosure rating, and water-resistant cable outlet.
Additionally, inductive proximity sensors of the IME product family from SICK are used to signal overtravel. The inductive proximity sensors limit the travel of the trackers and are mounted for the panels to get the most out of the solar radiation in both summer and winter.
The inductive proximity sensors allow using the optimum tracking paths, while at the same time detecting possible overtravel beyond the end position.
The EAR Group and its parent company, Siem Impianti also use other sensors from SICK’s portfolio including safety light curtains and photoelectric sensors.
Gianlucca Narducci appreciates the support received from SICK Italy as well as the company’s technical product specialists.