Indoor / Outdoor Test Stand for Solar Thermal Collectors
The idea is to mount a tracker, the thermostat and the complete data acquisition equipment on a carriage on tracks, which allows the collectors on the testing surface to be tested outdoors under natural conditions as well as indoors under the solar simulator. The tracker’s testing surface is 2.5 x 5 m: space enough for four standard solar collectors.
Figure 1: Schematic illustration of the test stand
The hydraulic system and the data acquisition equipment are such that all four collectors can be tested simultaneously outdoors. However, as the indoor testing surface is limited to 2 x 2.2 m, collectors under the solar simulator can only be tested consecutively.
The thermostat for parallel testing of up to four collectors, on a movable frame, was specially developed by TUV Immissionsschutz und Energiesysteme GmbH and Lauda GmbH for this application. In this unique design, the cold production, tempering and data acquisition are combined in one unit, which means that only the electrical connection and one network cable need to be disconnected for a change of position. To function smoothly under the Libyan climate conditions, both the control cabinet with the data acquisition equipment and controls and the tempering unit cabinet are air-conditioned.
The moveable frame is a modification of a trolley such as is used in the cement industry to move heavy loads. measX used the measurement system Almemo® by Ahlborn for the data acquisition. This system controls the thermostat as well as the data acquisition and can, for example, set the temperature test values.
To prevent the collector tests from being distorted by the heat radiation between the collector and the solar simulator’s hot metal halide lamps, a cold artificial sky is used. For the first time, this artificial sky, which consists of two parallel non-reflective, low-iron panes of glass, between which chilled air is circulated, was mounted directly on the lamp field.
The CSES test facilities conform to all current international testing standards in the field of solar thermal and PV modules. For solar thermal, this includes the ISO 9806 set of norms for collectors as well as the ISO 9459 set of norms for systems. There is also a testing facility for solar storage according to the European Technical Specification EN TS 12977-3 (there is currently no corresponding international norm).
In addition, the design includes all necessary test facilities to fulfill the requirements of ISO 9806-2 for serviceability tests of solar thermal liquid collectors. Besides smaller testing equipment, this includes a stand for testing performance in rain, shock and exposure conditions.
For long-term management of the operation with local personnel, BEG makes sure that the necessary know-how is communicated and offers training workshops in Germany and Libya. Other project partners are also involved in these training sessions.
The complete facility was installed in Libya at the end of 2007.