University of Twente Student Theses


Development of a single axis tracker for a hybrid solar system that can be integrated into building environments

Welle, R. ter (2010) Development of a single axis tracker for a hybrid solar system that can be integrated into building environments.

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Abstract:The Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) in Portici has many activities related to solar power and one of these involves the development of concentrating solar power (CSP) systems. ENEA therefore started a program for the development of a hybrid photovoltaic and thermal concentrating system. The subject of this assignment was in line with this program to design a hybrid solar tracker that can be aesthetically integrated into building environments, has low production costs, a high optical efficiency and can easily be produced. This product must help ENEA getting a prominent position in the worldwide development of concentrating hybrid solar systems. After a general orientation into CSP systems a study was done on how these systems work and are built up. The specific type of CSP system that was subject of this assignment uses a mirrored parabolic trough to reflect and concentrate solar radiation onto a receiver that converts the solar energy to electrical and thermal energy. By comparing different currently commercially available CSP systems for small-scale use, it became clear that this is only a small market, which focuses namely on efficiency and cost without paying attention to aesthetics. A cost breakdown of a comparable system showed the supporting structure, mirrors and receiver are the main components of the total costs. Small-scale use and the integration into building environments lead to a method to calculate the potential of a certain area so different locations can be compared for future fields of application. A lot of stakeholders are involved in the area of sustainable energy. For example the European Union with the 20-20-20 targets which demands 20% of the European energy consumption to come from renewable resources by the year of 2020. The general preferences of the stakeholders together with the demands from ENEA were combined into the requirements. One of the most important requirements was to be able to apply the system on surfaces without permanent connection to the floor or rooftop. Wind loads become an important factor in this case and calculations have been made for a ballast compartment to withstand these loads. The functions the product must fulfill together with the influence of the wind loads acted as a frame in which three concepts were developed with a shift in priority between cost and aesthetics. With ENEA preferring to distinguish itself from competitors by aesthetically integrating the product into building environments, the concept with higher priority for aesthetics over costs was chosen to further develop. The project resulted in a system with an integrated electromotor to track the sun during the day. Each module consists of a ballast part from PVC material that can be filled with sand to get the required weight to withstand wind loads. An aluminum structure supports the parabolic trough that consists of a mirror made from an aluminum sandwich structure, covered by an optional glass plate for protection of the mirror. To protect the system from extreme weather conditions the system rotates to a horizontal position so that the surface exposed to the wind is minimized. The supporting structure on the sides can be replaced by the same supporting part as is used in the middle to connect more modules in a long row. This makes the system modular because also the receiver can be connected by a coupling part. The power inverter that converts the direct current from the solar cells to alternating current limits the minimum (extra) field size. Eight modules, measuring 1.60 by 2.20 meters each, are needed for one power inverter to work efficiently. A field of this size yearly produces around 9600 kWh of thermal and 3500 kWh of electrical energy when exposed to a direct solar radiation of 1700 kWh/m2 a year. In total an efficiency of approximately 48% is reached this way. Because the receiver is still to be developed by ENEA these estimations remain fairly rough, especially for the thermal part. The final design fulfills almost all requirements. It depends however on the economic market whether the production methods for the different parts are appropriate because they are only suitable for a certain production number range. The system is also not fully plug and play, due to assembly actions that are still needed on the application sight and the needed coupling parts between the receivers for the modularity. The most important point of attention is the estimated price of 1500 euro’s per stretching meter which is 25% higher than the competitors. The final product has a comparable performance but aesthetically distinguishes itself from other systems, without the need to adjust the application surface. In the future development optimization of parts to lower the costs will be a major aspect. Also in this stage the receiver has to be developed so that better estimations on costs and performance can be made. To make the system more flexible, alternative solutions have to be found for the currently used power inverter that limits the minimum (extra) field size. The system’s potential to satisfy the demands of the European Union is high by applying the product to appropriate buildings.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:20 art studies
Programme:Industrial Design BSc (56955)
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