DuPont: Innovative concentrated photovoltaic module has housing made of strong, robust PET

The housing for a new and innovatively-designed concentrated photovoltaic module, developed by Concentración Solar La Mancha S.L., of Manzanares (Ciudad Real), Spain, is moulded from DuPont™ (www.dupont.com) Rynite® polyethylene terephthalate (PET). The material was selected due to its exceptionally low warpage, high stiffness and excellent electrical insulating properties. One of the first commercial installations of the CPV modules is scheduled for September 2008 at the ISFOC (Instituto de Sistemas Fotovoltaicos de Concentración) in Puertollano (Ciudad Real), with plans for a second, 1 MW-rated unit in Castilla La Mancha Community in due course.

Concentrated photovoltaic ( or CPV) uses mirrors or lenses to ‘concentrate’ or focus light from a relatively broad collection area onto a small area (as little as 1 cm2) of active semiconductor PV material based on Group III and V elements in the periodic table. These systems show very high cell conversion efficiencies of over 36 percent. The concentrated photovoltaic modules, developed by the Spanish start-up company Concentración Solar La Mancha S.L., consist of six concentrator elements and automatically track the sun’s movement across the sky to within 0.2° of accuracy. Such precision enables them to achieve efficiency levels of 20 to 24 percent in terms of electricity production, compared to 15 to 16 percent for modules with conventional silicon cells.

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They are housed and supported in a frame moulded from a mica- and glass-reinforced grade of DuPont™ Rynite® polyethylene terephthalate (PET), selected as an alternative to powder-coated aluminium. “We were clear from the outset that we wanted to replace metal with a high performance polymer due to the benefits associated with the change, including corrosion resistance, design flexibility and lower processing cost and material costs. Through the integration of additional functions in the housing, we were able to reduce the number of manufacturing steps,” explains Miguel Trinidad
Aragon, CEO of Concentración Solar La Mancha. Rynite® 935 BK505 was chosen for the application due to its exceptionally low warpage, high stiffness and excellent electrical insulating properties. Exposed to around-the-clock outdoor weather conditions, the material was required to provide excellent heat (temperatures of up to 85 °C) and UV resistance, as well as the structural support required for the entire CPV module to withstand high winds.

Fundamental to the project’s success has been the close working partnership between plastic injection-moulding specialist Teknia Plasticos Martos S.A.U of Jaén, Spain, Concentración Solar La Mancha and DuPont. Teknia worked closely with DuPont on mould design – the tool was actually produced in China and prepared within the shortest of time frames thanks to the support of DuPont China. “Despite the housing’s large dimensions (83.3 cm x 56.5 cm), complicated shape and the required wall thickness (3 mm), the excellent melt flow of Rynite® ensures the uniform filling on the mould cavity and the consistent production of moulded parts with good dimensional stability, low distortion and attractive surface qualities within short cycle times,” comments David Peña, development leader at Teknia Plasticos Martos.

Photo: The large housing for the concentrated photovoltaic module, measuring 83.3 cm x 56.5 cm, is moulded from DuPont™ Rynite® polyethylene terephthalate (PET) due to the material’s good dimensional stability, low distortion, attractive surface qualities and excellent melt flow.

DuPont de Nemours (Deutschland) GmbH, Bad Homburg v.d.H., Germany

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