Abstract: . . .  plate and tubular collectors is an oft-discussed theme. Depending on the application and the specific boundary conditions, the performance difference between the two collector types may be very small (for example domestic hot water systems with low solar fractions) or very large (if higher temperatures are required).  . . .
. . .  in collector assemblies with a large number of parallel connected tubes, the temperature stability of connection fittings and hail impact resistance of the glass tubes. Performance of evacuated tubular collectors from 1980 to 2000: The performance of thermal collectors can be described basically by the efficiency curve and the incident angle modifier. Especially for evacuated tubular collectors, the reference area is a much-discussed theme. For a comparison of different evacuated tubular collectors, . . .
. . .  entering the market, the potential for further improvement is smaller than for flat plate collectors. However, highperformance materials and better designs will undoubtedly lead to more efficient products. With the continuous optimisation of flat plate collectors, the performance gap relative to evacuated tubular collectors has been steadily reduced. This trend is predicted to continue in the years ahead. REFERENCE /1/ SPF-Info-CD, Solar collector database, measurements, design and construction details . . .
. . . SOLAR THERMAL COLLECTORS, STATE OF THE ART AND FURTHER DEVELOPMENT Ulrich Frei Institut für Solartechnik SPF, Hochschule für Technik HSR, Oberseestrasse 10, CH-8640 Rapperswil, Switzerland, Phone: + 41 55 222 48 21, Fax: + 41 55 222 48 44, ueli.frei@solarenergy.ch Abstract - The . . .
. . .  AND TUBULAR COLLECTORS OF THE YEARS 2000 AND 2010 The differences in performance between flat plate and tubular collectors is an oft-discussed theme. Depending on the application and the specific boundary conditions, the performance difference between the two collector types may be very small (for example domestic hot water systems with low solar fractions) or very large (if higher temperatures are required).  . . .
. . .  of the collector products. Thermal performance and quality may be identified on the basis of international standards (EN and ISO). It is much more difficult to objectively judge the visual design of a collector or its architectural integration in a particular building. Both aspects are subject to individual taste. During the last 20 years, the thermal performance and, just as importantly, the quality of the collectors have greatly improved. On the basis of the EN standard, the Solar-Keymark was established . . .
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