The SSPS-CRS plant was inaugurated as part of the International Energy Agency’s SSPS project (Small Solar Power Systems) in September 1981. Originally conceived to demonstrate continuous electricity generation, it used a receiver cooled by liquid sodium that also acted as the thermal storage medium.
At the present time, as with the CESA-I plant, it is a test facility devoted mainly to testing small solar receivers in the 200 to 350-kWth capacity range.
The heliostat field is made up of 91 39.3-m2 first generation units manufactured by Martin-Marietta. A second field north of it has 20 52-m2 and 65-m2 second-generation supporting heliostats manufactured by MBB and Asinel.
The original CRS heliostat field was improved several years ago with the conversion of all of its heliostats into completely autonomous units powered by photovoltaic energy, with centralized control communicated by radio by a concept developed and patented by PSA researchers. This first autonomous heliostat field, which does not require the use of channels or cabling, was made possible by financial assistance from the Ministry of Science and Technology’s PROFIT program.
The nominal average reflectivity of the field is 87%, the solar tracking error is 1.2 mrad per axis and the optical reflected beam quality is 3 mrad. Under typical conditions of 950 W/m2, total field capacity is 2.7 MWth and peak flux is 2.5 MW/m2. 99% of the power is collected in a 2.5-m-diameter circumference and 90% in a 1.8-m circumference.
The 43-m-high metal tower has two test platforms. The first is a two-level open area at 32 and 26 m prepared for testing new receivers for thermochemical applications.
The second test platform is at the top of the tower at 43 m, and houses an enclosed room with crane and calorimetric test bed for the evaluation of small atmospheric-pressure volumetric receivers, and solar reactors for hydrogen production. The tower infrastructure is completed with a 600-kg-capacity crane and a 1000-kg-capacity rack elevator.
The facility’s calorimetric test bed consists of an air-recirculation circuit with axial fan and 40-kW electric heater to control the air-return temperature as well as instrumentation to measure the temperature, pressure and flow rate. Absorber outlet air is cooled by a water-cooled heat exchanger used for indirect thermal balance. The calorimetric bench has been successfully employed since 1986 with logical improvements and updating, for the evaluation of all kinds of metal and ceramic volumetric absorbers.
Two PROHERMES II (Programmable Heliostat and Receiver Measuring System II) measurement systems are used to characterize the concentrated solar radiation flux map on both towers. For this, the concentrated incident solar beam is intercepted by a Lambertian target, located on a plane parallel and immediately in front of the receiver aperture, at which moment a high-resolution CCD camera records the image. After its exhaustive treatment, the total power can be integrated, and the rest of the magnitudes of interest, such as peak flux or statistical energy distribution parameters on the receiver can be calculated.