H. Kerskes*, B. Mette, H. Drtick, H. Mtiller-Steinhagen

Institute for Thermodynamics and Thermal Engineering (ITW),

University of Stuttgart, Pfaffenwaldring 6, 70550 Stuttgart, Germany
Tel.:++49-711-685-63534

Corresponding Author: kerskes@itw. uni-stuttgart. de
Abstract

System tests according to the EN 12976 test procedures are a basis for factory made Solar Keymark system certification. To obtain the Solar Keymark certificate, each system configuration of a solar domestic hot water system (DHW) has to be tested by an accredited testing laboratory. As companies often offer a product line of their solar DHW systems, it is desirable to have a calculation tool that is able to predict the thermal performance of the whole product line without the need to test each of the system configurations. This paper presents the main elements of the Solar Keymark certification program as well as a mathematical procedure developed at the ITW with which it is possible to extrapolate performance test results of one tested system to systems of the same product line.

Keywords: Solar Keymark certification, solar domestic hot water systems, DST

1. Introduction

With the implementation of Solar Keymark certification in the year 2003, a pan-European quality label for solar thermal products was established for the first time /1/.

The aim of the Solar Keymark label is to break the existing trade barriers within the European market. A solar thermal system or solar collector certified according to the Solar Keymark scheme rules fulfils the relevant European Standards and is hence qualified for acceptance by the national regulatory and financial authority, e. g. with regard to financial incentives.

Thereby it is avoided that a system already tested by an accredited testing laboratory has to be tested again by national laboratories. For manufacturers of solar thermal systems the Solar Keymark is an instrument to save time and money and to demonstrate the quality of their products. On the other hand customers benefit from the guarantee to buy an approved product.

In 2004 the first system tests according to the EN 12976 test procedures /2/ as basis for factory made Solar Keymark system certification were carried out at ITW. In the meantime about 35 factory made solar thermal systems are Solar Keymark certified by several European certification bodies and the number of requested system tests is growing rapidly.