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As yet, procedures for long-term tests of photovoltaic modules in outdoor conditions have not been considered by international standardization committees. Although many laboratories perform long-term PV outdoor tests, a commonly agreed and standardized procedure has so far not been adopted. The European Distributed Energy Resources Laboratories’ (DERlab) approach to filling the gap of international standardization has led to the development of a basic protocol that complies with European and international standards, while providing specific common guidelines and procedures for measuring the energy yield of PV modules for at least one year in outdoor conditions. The DERlab procedures for long-term PV module testing are described in this paper, and the range of analyses that can be derived from the data, such as module degradation, are discussed. The paper also presents the DERlab approach to measuring module performance in outdoor conditions, which can be used to complement energy-rating methods suggested in international standards. DERlab has created consistent measuring procedures that allow the direct comparison of the energy yield of solar modules taking into account the site-specific factors of different locations and varying climatic conditions, as well as a maintenance guideline.
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In trying to introduce its relatively new technology to traditional utility customers, the photovoltaic industry often finds itself in the awkward position of trying to sell a product to a customer who may not want to buy. The up-front capital costs of new solar plants (that deliver power only intermittently) can be less than appealing. Large-scale grid integration will therefore be accelerated by PV technologies that best fit the profile of traditional power sources. In addition to low cost, this includes high capacity factors and the ability to better match demand during daylight hours.
Concentrator photovoltaic (CPV) power plants are now being integrated into the grid at megawatt scales. By performing light collection using acrylic, silicone, or glass optics instead of semiconductors, the material cost balance of PV is fundamentally shifted. The world’s most efficient solar cells can then be employed, and maintaining tracking of the sun becomes economically favorable across vast sunny locales worldwide. With AC system efficiencies in excess of 25%, the resulting CPV power plants produce high energy yields throughout the year and deliver the high capacity factors demanded by utility customers. Since semiconductors are a minority component cost, manufacturing capital costs are lower than for any other PV technology, allowing for rapid scale-up and field deployment. This article will describe the state of the art of CPV technology, field performance results, and the outlook for near-term deployments.
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