A first Ultimate Trough (UT) collector demonstration loop was successfully integrated in an existing solar power plant in California and is now put into operation.


Its huge dimensions of one Solar Collector Assembly (SCA) with an aperture width of 7.5 m and a length of 240 m make it the largest parabolic trough ever built and operated.




With the Ultimate Trough®, the industrial partners are focusing on large scale solar thermal power plants in the range of 50 – 250 MWe. Creating additional benefits utilising the “economy of scale” effect, such plants will make solar power plants even more competitive. The very large dimensions enable high structural stiffness of the support structure decreasing deformations under operation loads, while simultaneously improving optical performance.


The goal of the demonstration loop project is the demonstration of the developed fabrication and erection concepts and their respective costs. The collector efficiency is currently measured and confirmed under real life conditions to warrant performance and safety for the design of upcoming solar thermal power plants.

First results show that expected performance values may even be exceeded. Detailed technical information (drawings, specifications etc.) for the full size commercial collector field are available.


The development is co-funded by the German Federal Ministry for the Environment, Nature conservation and Nuclear Safety, reference no. 0325232.

About schlaich bergermann und partner, sbp sonne gmbh:

schlaich bergermann und partner, sbp sonne gmbh are consulting engineers and technology developers for solar power plants with 30 years of experience in feasibility studies, design, planning, optimization, erection and commissioning of CSP systems.




Compared to the Eurotrough, the very successful first collector generation developed by schlaich bergermann und partner, the size of the new UT collector has more than doubled.

The Eurotrough has already been integrated in many multi Megawatt parabolic trough power plants all over the world. With the new UTcollector design parabolic trough plant competitiveness is expected to rise by 25 % and will thus contribute significantly to further cost reduction of future parabolic trough power plants.

In 2010 schlaich bergermann und partner (sbp) and Fraunhofer Institute for Material Flow and Logistics (IML) started under the leadership of Flabeg Holding GmbH (Flabeg) the development of the next generation collector for parabolic trough power plants with the aim to reduce the overall solar field cost by 20 to 25 % dependent on field configurations.

The impressive cost reduction is a result out of an elaborate technoeconomical study comprising novel advanced technical features, new manufacturing methods and optical improvements.


The new collector design, the so-called ‘Ultimate Trough ®design, was developed with an aperture area of 1.689 m² and an aperture width of 7.5 m. The collector connected to one drive system is divided into 10 Solar Collector Elements (SCE) with a length of 24 m each. A first prototype collector has been built and extensively tested in a German production hall in 2011. Detailed photogrammetry and deflectometry measurements confirmed the excellent optical performance of the collector.