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Solar Two was a collaborative, cost-shared project between 11 U. S. industry and utility partners and the U. S. Department of Energy to validate molten-salt power tower technology. The Solar Two plant, located east of Barstow, CA, comprised 1926 heliostats, a receiver, a thermal storage system, a steam generation system, and steam-turbine power block. Molten nitrate salt was used as the heat transfer fluid and storage media. The steam generator powered a 10-MWe (megawatt electric), conventional Rankine cycle turbine. Solar Two operated from June 1996 to April 1999. The major objective of the test and evaluation phase of the project was to validate the technical characteristics of a molten salt power tower. This report describes the significant results from the test and evaluation activities, the operating experience of each major system, and overall plant performance. Tests were conducted to measure the power output (MW) of the each major system, the efficiencies of the heliostat, receiver, thermal storage, and electric power generation systems and the daily energy collected, daily thermal-to-electric conversion, and daily parasitic energy consumption. Also included are detailed test and evaluation reports.

The report documents a Colorado State University Solar Energy Applications Laboratory study investigating cost-effective ways of improving fabrication and installation of residential solar energy heating systems. The study entailed on-site observation of twelve installations focusing on the phase of mounting and manifolding of solar collectors. Time lapse photography and work measurement techniques were employed to record these installations. Generic collector types studied included air and liquid panels both internally and externally manifolded. Principal findings of the study synthesized from field observations, analysis of photographic data, time studies, and discussion with installation personnel and manufacturers' representatives are presented in the technical report. iii Conclusion/Inference: Manufacturers and installers should recognize the potential for damage to pipe fittings from over-torquing. Recommendation: Manufacturers should specify the tools required for installation and recommend using wrenches of a particular length, since over-torquing tends to occur when long wrenches are used. Observation 11 Rigid connections between internally manifolded liquid collectors do not allow for much alignment error. Unevenness of the mounting surface (e.g., the roof) may contribute further to the problem. Conclusion/Inference: System leaks may occur due to misalignment of collectors beyond the capacity to accept misalignment. Recommendation: Use flexible connections between the rows (columns) of collectors or use a gauge to ensure uniform dimensions of installed pipe fittings. Collector manifolds should be designed to tolerate reasonable misalignments. Observation 12 Collectors are typically 36 in. (91cm) wide, making it difficult to install, anchor, and capstrip by reaching across the panel. Conclusion/Inference: A "narrow" panel may allow the installation of between panel fittings without requiring several ladders and/or walking across the panels. Workers could then systematically install an array while working in one direction with a minimum of workers and movement. Recommendations: Manufacturers should consider high aspect ratio panel designs. Observation 13 Most collector arrays are at least 15 ft in height, whereas most collectors are approximately eight ft in height. Conclusion/Inference: Cost per square foot of collector installed could be reduced if collectors were shipped and installed in modules longer than eight feet. Leakage problems would also be reduced due to the need for fewer connections. Recommendation: The use of a light weight crane (see Observation 5) would make it possible to build and ship collectors in a more cost-effective size. Observation 14 During installation on sunny days, exposed panels reach high internal temperatures at the absorber. Hot panels in such cases can be handled only with gloves which are cumbersome to wear during other steps of 9 the installation. Heat escaping from panels makes working around the array uncomfortable. Glare from exposed glazing also reduces worker eff...

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