In the framework of the European Committee for Standardization, CEN (Comité Européen de Normalisation), the operation of a technical committee dealing with solar thermal collectors and systems has been established. Specifically, CEN/TC 312, “Thermal solar systems and components”, was created in 1994, following a request of the European Solar Thermal Industry Federation (ESTIF) to the CEN Central Secretariat. The scope of CEN/TC 312 is the preparation of European standards to cover terminology, general requirements, characteristics, and test methods of thermal solar systems and components.
The primary aim of the European standards is to facilitate the exchange of goods and services through the elimination of technical barriers to trade. The use of European standards by industry and social and economic partners is voluntary unless the European standard is related to European legislation (directives). Furthermore, conformity to such standards may be a presumption for solar projects to get a subsidy from national/regional renewable energy systems supporting programs (Kotsaki, 2001).
For the elaboration of European technical standards, corresponding national documents as well as international standards (ISO) have been taken into consideration. It should be noted that, compared with the existing standards, the European norms under consideration are performing a step forward, since they incorporate new features, such as quality and reliability requirements.
In April 2001, CEN started publishing a series of standards related to solar collectors and systems testing. With the publication of these European standards, all national standards related to the same topic and having conflicting provisions were (or have to be) withdrawn by the nations of the European Community. Some of these standards were revised in 2006 and are now under their second 5-year systematic review. A complete list of these standards is as follows:
• EN 12975-1:2006 + A1:2010. Thermal solar systems and components—Solar collectors—Part 1: General requirements. This European standard specifies requirements on durability (including mechanical strength), reliability, and safety for liquid-heating solar collectors. It also includes provisions for evaluation of conformity to these requirements. It should be noted that the A1:2010 in the standard reference number denotes a minor amendment which was made in 2010 to change the scope of the standard so as to extend its application for concentrating collectors as well.
• EN 12975-2:2006. Thermal solar systems and components—Solar collectors—Part 2: Test methods. This European standard establishes test methods for validating the durability, reliability, and safety requirements for liquid-heating collectors as specified in EN 12975-1. This standard also includes three test methods for the thermal performance characterization for liquid-heating collectors.
• EN 12976-1:2006. Thermal solar systems and components—Factory-made systems—Part 1: General requirements. This European standard specifies requirements on durability, reliability, and safety for factory-made solar systems. This standard also includes provisions for evaluation of conformity to these requirements.
• EN 12976-2:2006. Thermal solar systems and components—Factory-made systems—Part 2: Test methods. This European standard specifies test methods for validating the requirements for factory-made solar systems as specified in EN 12976-1. The standard also includes two test methods for the thermal performance characterization by means of whole-system testing.
• EN 12977-1:2012. Thermal solar systems and components—Custom-built systems—Part 1: General requirements for solar water heaters and combisystems. This European standard specifies requirements on durability, reliability, and safety of small and large custom-built solar heating and cooling systems with liquid heat transfer medium in the collector loop for residential buildings and similar applications. The standard also contains requirements on the design process of large custom-built systems.
• EN 12977-2:2012. Thermal solar systems and components—Custom-built systems—Part 2: Test methods for solar water heaters and combisystems. This European standard applies to small and large custom-built solar heating systems with liquid heat transfer medium for residential buildings and similar applications and specifies test methods for verification of the requirements specified in EN 12977-1. The standard also includes a method for thermal performance characterization and system performance prediction of small custom-built systems by means of component testing and system simulation.
• EN 12977-3:2012. Thermal solar systems and components—Custom-built systems—Part 3: Performance test methods for solar water heating stores. This European standard specifies test methods for the performance characterization of stores intended for use in small custom-built systems as specified in EN 12977-1.
• EN 12977-4:2012. Thermal solar systems and components—Custom-built systems—Part 4: Performance test methods for solar combistores. This European standard specifies test methods for the performance characterization of stores which are intended for use in small custom-built systems as specified in EN 12977-1. Stores tested according to this document are commonly used in solar combisystems.
• EN 12977-5:2012. Thermal solar systems and components—Custom-built systems—Part 5: Performance test methods for control equipment. This European standard specifies performance test methods for control equipment as well as requirements on accuracy, durability, and reliability of the control equipment.
• EN ISO 9488:1999. Solar energy—Vocabulary (ISO 9488:1999). This European-International standard defines basic terms relating to solar energy and has been elaborated in common with ISO.
The elaboration of these standards has been achieved through a wide European collaboration of all interested parties, such as manufacturers, researchers, testing institutes, and standardization bodies. Furthermore, these standards will promote a fair competition among producers of solar energy equipment on the market, since low-quality/low-price products will be easier to be identified by customers, based on uniform test reports comparable throughout Europe.
The increased public awareness of the environmental aspects is reinforced by these standards, which help ensure the quality level for the consumer and provide more confidence in the new solar heating technology and products available.
4.10.1 Solar keymark
The Solar Keymark certification scheme was initiated by the ESTIF to avoid internal European trade barriers due to different requirements in national subsidy schemes and regulations.
Before the European standards and the Solar Keymark were established, solar thermal products had to be tested and certified according to different national standards and requirements. The Solar Keymark idea is that only one test and one certificate are necessary to fulfill all requirements in all EU member states.
The Solar Keymark certification scheme was introduced to harmonize national requirements for solar thermal products in Europe. The objective is that, once tested and certified, the product should have access to all national markets. This goal has now been achieved, except for some minor supplementary requirements in a few member states.
The CEN Solar Keymark certification scheme has been available for solar thermal products in Europe since 2003. The Solar Keymark states conformity with the European standards for solar thermal products. The CEN Keymark is the pan-European voluntary third-party certification mark, demonstrating to users and consumers that a product conforms to the relevant European standard (Nielsen, 2007).
The Solar Keymark is the keymark certification scheme applied specifically for solar thermal collectors and systems, stating conformity with the following European standards:
• EN12975. Thermal solar systems and components—Solar collectors.
• EN12976. Thermal solar systems and components—Factory-made systems.
Solar Keymark is the key to the European market because:
• Products with the Solar Keymark have access to all national subsidy schemes in EU member states.
• In some member states (e.g. Germany), it is now obligatory that solar collectors show the Keymark label.
• People expect the Solar Keymark; most collectors sold now are Keymark certified.
The main elements of the party Keymark certification are:
• Type testing according to European standards (test samples to be sampled by an independent inspector).
• Initial inspection of factory production control (quality management system at ISO 9001 level).
• Surveillance: annual inspection of factory production control.
• Biannual “surveillance test”: detailed inspection of products.
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