The Basic Element of Solar Power Technologies: Advanced Components and Systems

The advanced components and systems R&D goals include lowering costs and improving performance and reliability of solar mirrors and unifying test methods to standardize qualification requirements of CSP materials, components, and systems.

Hamilton Sunstrand SLS Rocketdyne Corporation, Central-Receiver Panel Fabrication and Testing - Manufacturing and testing of a large-scale (200-megawatt) molten-salt solar receiver panel for power-tower technology.

Advanced Components and Systems Research and Development. As part of its research in concentrating solar power (CSP), the U.S Department of Energy sponsors research and development (R&D) for advanced components and systems. The R&D goals in this area are to

Lower costs and improve performance and reliability of solar mirrors

Support CSP subcontracts and industry-program needs, primarily characterizing and testing materials developed under these subcontracts 

Broaden and unify test methods to standardize qualification requirements of CSP materials, components, and systems.

This page summarizes key advanced components and systems R&D activities by the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories to attain the above goals in three areas: Mirror characterization and testing;  Testing standards and reliability testing methods; Industry support.

Mirror Characterization and Testing. Low-cost, high-performance, durable advanced optical materials are needed to meet the demands of advanced system designs and achieve the cost and performance goals to commercialize CSP technologies. Our overall objective is to develop, validate, and aid the commercialization of advanced reflector systems that can dramatically reduce CSP costs.

The solar industry recognizes the value of our advanced concepts R&D, particularly in optical characterization; accelerated and outdoor testing of advanced solar reflectors; and our repository of material durability data. This work is not duplicated by private industry. Below are some representative projects.

Advanced Optical Materials. Scientists R&D activities include optically characterizing advanced reflector materials, determining the lifetime of solar reflector materials by accelerated and outdoor testing of commercial and experimental materials, and supporting industry and program needs. This work improves reliability, reduces installed capital cost of the solar field for parabolic troughs, and improves system reliability for dish/Stirling and power tower systems.

Candidate reflector materials are identified based on their potential for low cost and high optical performance and durability. All materials are characterized prior to exposure testing and as a function of exposure time to assess optical durability. NREL's Advanced Optical Materials Laboratory has substantial analytical and measurement capabilities to develop and test the optical performance and long-term durability of optical materials used in CSP systems.

Some new efforts planned include: developing better reflectance-measuring capabilities; converting the current database of candidate solar mirrors to a Web-based system; determining the acceleration factor for damp-heat chambers; and correlating salt spray and damp-heat exposure to accelerated light-exposure testing.

Remarkable changes have occurred during the last two decades in CSP solar reflectors and receiver tubes, glazings for buildings, photovoltaic modules, flat-plate collectors, and electrochromic windows. These changes have led to improved performance and reduced initial costs. However, major factors in maintenance costs and the long-term performance of these technologies are the performance loss from surface soiling and the cost to clean the surface. For example, reduced reflectivity of a solar mirror due to soiling can lead to an 8%–12% drop in performance between cleanings. The issue of soiling and cleaning must be dealt with before CSP plants are deployed on a massive scale in low-water desert environments.

We are researching advanced hardcoats, barriers, antisoiling coatings, and cleaning characterization and testing. One study involves correlating scratch resistance and water and oxygen permeation rates of advanced hardcoats and barrier coatings with durability of solar mirrors. We are also determining soiling rates for different materials at different sites.

Testing Standards and Reliability Testing Methods. CSP standards ensure that unreliable, defective systems are not deployed, which could irreparably damage the reputation of the technology. Reliability testing directly addresses factors that are vital to successfully commercializing CSP products, such as reasonable cost, performance, and durability. This testing permits a quantitative analysis of levelized cost of electricity by providing estimates of service lifetime, operating and maintenance costs, and reasonable warranties. Representative projects in this area include the following:

Lack of well-developed standards can impede technological progress and lead to disadvantages associated with poor installations. For example, unsafe or unreliable installations can decrease confidence by investors, developers, installers, and end-users. International consensus on codes and standards is important to avoid delays in implementing new CSP projects and the associated additional costs.

We are reviewing existing performance parameters, test guidelines, and standards to help identify and develop CSP testing standards in future years. We are also drafting definitions of performance parameters for consensus by industry and the international community.

Testing procedures for materials, component performance, controls, tracking accuracy, and system performance are also being reviewed. By using round-robin testing, we will compare various measurement techniques and determine the equivalency of results generated by the collaborating participants. This allows the determination of the type and adequacy of existing test equipment and need for developing new test equipment and procedures.

Scientists are assessing existing testing standards in terms of what is available and useful and what needs to be improved or developed. We will then develop testing standards tailored to CSP materials, components, and systems.

Scientists are reviewing existing accelerated reliability test procedures and identifying necessary improvements and additional tests. We are also developing accelerated testing protocols that include screening, qualification, and lifetime tests. Highly accelerated initial screening tests will determine if a material or product can pass a preliminary set of tests before being subjected to other longer-term reliability testing to predict lifetime.

Scientists are also focusing on qualification tests, which are relatively short-term tests that can uncover known mechanisms. These tests do not typically demonstrate unknown problems or indicate lifetime, but they provide some measure of reliability.

In-service exposure testing identifies realistic failure mechanisms experienced in the field. Scientists carefully monitor time-dependent climatic stresses experienced by CSP materials, components, and systems in the field. These data are used to derive correlations with accelerated test results and validate associated damage-function models.

Industry Support. Some of DOE's technical activities support the awardees of financial opportunities for concentrating solar power. Other projects, discussed under Industry Support on the Linear Concentrator R&D page, include work by 3M (Hardcoats for Polymeric Mirrors); Abengoa Solar (Advanced Front Surface Polymeric Reflector); Alcoa, Inc. (Aluminum Reflector); and PPG Industries (High-Value Mirrors).

The complete list of DOE-funded CSP projects is available on the Concentrating Solar Power Industry Projects page that specifically includes the advanced components and systems projects.

 

Vasil Sidorov on April 21, 2011 from US DOE Office of Science

Queltanews office,

Technopark QUELTA,

Nizhyn Laboratories of Scanning Devices

sidorovvasil@gmail.com

 


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