OPAC

Facility for the Optical Characterization and Durability Testing of Solar Components - OPAC

This facility is the largest one worldwide devoted to the complete study of the materials used in the optical components of concentrating solar thermal systems (reflectors, receivers, transparent covers, receiver particles, etc.), allowing the determination of characteristic optical parameters, their possible deterioration along the time, as well as different O&M aspects, such as soiling evaluation and mitigation (including cleaning strategies). It is the result of a joint collaborative project between CIEMAT and DLR and it is composed by several unique outdoor facilities to assess the possible degradation mechanisms affecting these optical component (including a high number of test benches that simulate different operating conditions) and five full-equipped laboratories to reproduce such degradation mechanisms under accelerated aging conditions in weathering chambers. The following equipment is available in the laboratory of optical characterization of solar components (see Figure 1.a):

Three portable specular reflectometers, Devices and Services Model 15R-USB, for measuring specular reflectance at 15° incidence angle, 660 nm wavelength and different aperture angles (3.5, 7.5, 12.5 and 23 mrad).
One portable specular reflectometer, Devices and Services model MWR, for measuring specular reflectance at 15° incidence angle, 460, 550, 650 and 720 nm wavelength and at different aperture angles (2.3, 3.5, 7.5, 12.5 and 23 mrad).
One portable reflectometer, PSE model pFlex 2.1, for measuring specular reflectance at 8° incidence angle, 470, 525 and 625 nm wavelength, and 67 mrad aperture angle.
One portable reflectometer, Zepren model Condor, for measuring specular reflectance at 12° incidence angle, 435, 525, 650, 780, 940 and 1050 nm wavelengths, and 145 mrad aperture angle.
One portable reflectometer, Konica Minolta model CM-700d, for measuring hemispherical and diffuse reflectance at 8° incidence angle, and 400-700 nm wavelength range.
One portable glossmeter, Zehntner model 1130, for indirect measurements of solar reflectance, at 20, 60 and 85° incidence angle.
One reflectometer prototype for measuring specular reflectance in a 5 cm diameter with spatial resolution of 10 pixel/mm, which measures at various wavelengths and aperture angles (model SR2, designed and patented by DLR).
One spectral Specular Reflectometer S2R for measuring specular reflectance spectra at variable incidence angles of 8-70°, in the wavelength range 280-2500 nm, and discrete acceptance angles of 7.4, 12.3, 14.8, 20.2, 35.9 and 107.4 mrad (designed and patented by DLR).
Two spectrophotometers, Perkin Elmer model Lambda 1050, with 150-mm diameter Labsphere integrating spheres for measuring hemispherical reflectance, absorptance and transmittance at 8° incidence angle in the wavelength range 280-2500 nm, and a specular reflectance accessory with 0 to 68° incidence angles (URA).
One infrared spectrometer, Perkin Elmer Frontier FTIR, with a 76.2-mm diameter Pike integrating sphere for measuring emittance at 12° incidence angle in the wavelength range 2-14 μm.
One Nikon D3 camera and 90 cm Cubalite kit for photos of specular surfaces without parasitic reflections.
One 3D microscope, Zeiss Axio model CSM 700, with magnifications of 5, 10, 20, 50 and 100 for finding the profiles and roughness of optical surfaces.
One 3D microscope, Leica model M250 C, with magnifications in the range of 7.8 to 160.
One Parstat 4000 impedance system to analyse the corrosion of reflector materials.
One tensiometer, Attension Theta model 200 Basic, for static and dynamic contact angle assessment, which is a key parameter to study the performance of the anti-soiling coatings applied to solar reflectors and receiver tubes.
A general Purpose Optical bench as accessory for the Perkin Elmer Lambda 1050 spectrophotometer with advanced features for mounting optical devices for the development of new measurement instruments.

The four laboratories for the solar components durability analysis are designed for accelerated ageing tests of these materials with the purpose of predicting in a short time, the behaviour during their useful lifetime (see Figure 1.b). To do this, the environmental variables producing degradation of solar components when they are exposed to outdoor conditions are applied in a controlled manner, both separately and in combination. The following equipment is available for these accelerated ageing tests:

One weathering chamber, Vöstch model VCC3 0034, to test the material resistance against corrosive gasses (H2S, Cl2, NO2, SO2) in combination with temperature and humidity (335 L), (see Figure 1.c).
Two weathering chambers, ATLAS model SC340MH, for temperature (from -40 °C to +120 °C), humidity (from 10 % to 90 %), solar radiation (from 280 to 3,000 nm) and rainfall (340 L).
One weathering chamber, Binder model MKF 720, where UV light (with a peak at 340 nm) can be applied in combination with a wide range of temperature and humidity conditions.
One weathering chamber, Memmert model HCP108, to apply humidity (20-95 %) and temperature (20-90 °C with humidity and 20-160 °C without humidity).
One weathering chamber, Ineltec model CKEST 300, for humidity and condensation testing with temperatures up to 70°C (300 L).
One salt spray chamber, Vötsch model VSC450, with temperatures from 10 °C to 50°C (450 L).
One salt spray chamber, Erichsen model 608/1000 L, with temperatures from 10 °C to 50 °C.
Two radiation chambers, ATLAS model UV-Test, where UV light (with a peak at 340 nm), condensation and temperature can be applied. One of the chambers also includes rain simulation.
One Ultraviolet chamber, Hönle model UVA Cube.
One SC100 heated water bath, to perform the Machu test, according to the Qualitest guideline.
One sandstorm chamber, Control Técnica/ITS GmbH, with wind speeds up to 30 m/s and dust concentrations up to 2.5 g/m³.
One cleaning abrasion device, Erichsen model 494, to test the degradation due to the cleaning brushes, with several cleaning accessories.
Two linear abraser, Taber model 5750, to check the materials resistance against the abrasion.
One cross-cut tester, Lumakin model A-29, to analyse the possible detachment of the paint layers.
One pull-off tester, DeFelsko model PosiTest AT-A, to analyse the possible detachment of the paint layers.
One soiling Pipe for simple sand erosion experiments based on DIN 52348. Erodent material hitting the specimen after around 160 cm of free fall under adjustable impact angles (designed by DLR).
One artificial soiling chamber, equipped with the aerosol generator SAG410/L from TOPAS GmbH and an ultrasonic nebulizer to reach a realistic soiling picture on reflector samples (designed by DLR).
Several devices for thermal cycles specially designed at the PSA by CIEMAT and DLR.

Figure 1.a - Optical characterization lab

Figure 1.b - Durability analysis lab

Figure 1.c - Weathering chamber