The solar field within a solar power plant has to be optimized in several aspects. First optical and thermal design is necessary to develop technical solutions with large efficiency. Secondly the materials used shall comply with the necessary optical and thermal performance specifications, and have to withstand the environmental and operation stresses for sufficiently long time. Thirdly the assembly of individual components has to be controlled and qualified. And last but not least, the costs of the collector have to be minimized. Having costs in mind, optical and thermal performance as wells as longevity become the key issues in collector optimization.

When overall performance does not meet the expectations, it is often difficult to trace back the problems to subsystems. Therefore a chain of quality measures should be used parallel to the assembly process of a collector. The measures generally consist of a testing procedure plus technical specifications. The testing can be either on-site in an outdoor environment or indoors in a laboratory or production place. We were working on the latter approach for several reasons:

• — for measurements in the laboratory external perturbations can be minimized and therefore the level of precision in general is higher

• — rejections within the production can be noticed in an early stage

• — testing methods developed can be modified to support quality control in a production line

Optical and thermal qualification will help manufacturers and construction companies to control collector performance as stipulated in the specifications. Some properties of the key components, i. e., thermal receiver, secondary and primary mirrors, have to be determined.