Passive Solar Tracking for Energy and Lighting ...

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GRØN DYST 2014 Technical University of Denmark

Passive Solar Tracking for Energy and Lighting Applications
Author:N.S. Sigurdarson (DTU Mechanical Engineering, Technical University of Denmark, Denmark)
Date: 2014-06-27     Track: Main     Session: 1

Solar tracking systems – that allow solar energy systems to adjust their position in accordance with the movement of the sun across the sky - are used to optimize the energy output from solar energy systems, increasing the energy yield by up to 80 %. Yet, tracking systems are more or less only used in large scale energy parks, due to the high cost, complex installation, and the long time it takes to achieve a return of investment. This project - conducted in collaboration with Velux A/S and DTU MEK - entails the development of a simple, inexpensive, passive solar tracking concept that does not require an external power source, for use in photovoltaic-, solar thermal-, and daylighting systems, in an effort to improve their performance. To ensure simplicity allowing for low potential manufacturing costs, the focus of the project was concentrated on finding a way of creating passive sun-following movement. This was done through actuation that is entirely powered and controlled by the angle of incidence and intensity of sunlight. As such, the aim was to utilize the relative temperature difference, between sunlight and shade that occurs due to the continuously changing intensity-, and angle of incidence of sunlight, both daily and seasonally. In order to create actuation as a reaction to relative changes in temperature, a solid thermal expansion principle as seen in thermal expansion systems such as thermometers and linear thermal microactuators was used as a basis.