We use an assortment of indoor equipment to test modules and systems under simulated and accelerated conditions, as well as to perform module packaging R&D.
Our equipment is housed in several laboratories in buildings across NREL:
- High-Bay Accelerated Testing Laboratory (OTF)
- Failure Analysis (OTF)
- Data Acquisition and Calibration (OTF)
- Optical Mechanical Characterization Laboratory (FTLB/153-01)
- Thin-Film Deposition and Sample Preparation Laboratory (FTLB/158-02)
- Accelerated Exposure Testing Laboratory (FTLB/158-03)
- PV Module Encapsulation Research Laboratory (MERL, SERF/E216)
Described below is some of the equipment we use, grouped by laboratory location, as well as a person to contact for more information.
High-Bay Accelerated Testing Laboratory (OTF)
The OTF High-Bay Laboratory houses the OTF accelerated testing equipment, which can be used to weather PV modules in environments with controlled temperature, UV exposure, and relative humidity.
Atlas XR260—Accelerated Xenon weathering system (2.5 suns full spectrum; temperature-humidity cycling; light soaking; 6' x 4' module capacity)
UV exposure unit—UVA fluorescent light-soaking (4' x 8' test plane)
BMA Environmental chambers (2)—Temperature-humidity cycling; electrical module biasing during cycling; 31 cu. ft. and 80 cu. ft.
Failure Analysis (OTF)
This laboratory contains additional testing and evaluation equipment; for more information, contact Nick Bosco.
Module leakage current testing—'Hi-pot' testing; modules tested either dry or immersed in wetting solution while high voltage is applied.
IR Camera—Takes infra-red photographs of systems or modules to pinpoint which areas are malfunctioning. For more information, contact Nick Bosco.
Data Acquisition and Calibration (OTF)
The equipment in this laboratory is primarily used to collect, monitor, and store data coming from our field-testing systems in the OTF array field; for more information, contact Bill Sekulic.
Data loggers—Log the data from data acquisition systems
IV-curve tracers—Assess the health of a module/module string
National Instruments Field Point System/Labview programming—Data acquisition system that gathers and saves data from systems in OTF array field
Campbell Scientific—Data acquisition system that gathers and saves data from systems in OTF array field
Calibration standards equipment—Checks that data acquisition system calibration is correct and according to standard
Optical Mechanical Characterization Laboratory (FTLB/158-01)
For general information about the laboratory, contact Mike Kempe.
Optical Characterization Equipment
The equipment described below is useful in measuring the optical properties of test samples—their ability to reflect or transmit light. For more information, contact Cheryl Kennedy.
Lambda 9 Spectrophotometer—Versatile, high-performance double-beam, double-monochrometer UV-visible-NIR spectrophotometer with integrating-sphere attachments; can measure the hemispherical reflectance and transmittance of samples compared with secondary reflectance standard; the absolute reflectance to be measured as per ASTM E903-82 for wavelengths, 250 to 2,500 nm for reflectance and 200 to 2,600 nm for transmittance
D&S Instruments Portable Specular Reflectometer 15R—Field and laboratory measurements of specular reflectance (non-scattered) on curved or flat samples; 660 nm LED and collimating optics produce 10-mm diameter source beam, which is focused through three-thumbwheel selectable aperture; standard acceptance angles are 7, 15, and 25 milliradians
Microscopes accessorized with digital imagery
Meteorological monitoring/recording station—Currently used to monitor/record local conditions at the Golden, CO outdoor test site
Mechanical Characterization Equipment
We use the equipment described below to characterize the mechanical properties of test samples—strength, adhesion, and ability to keep out moisture and oxygen. For more information, contact Mike Kempe.
Instron 5500R—Electromechanical test instrument; computer system allows dynamic testing; tabletop load-frame for maximum load of 0.5 kN; performs the following mechanical tests for metals, wood, polymers, and other materials at -150°C to 600°C:
Compression—Yield strength, yield point, elastic limit, and compressive strength
Tensile—Ultimate tensile strength, modulus of elasticity, or Young's modulus
Modulus of elasticity in shear, yield shear strength, ultimate shear strength, modulus of rupture in shear, and ductility
Creep properties and stress relaxation, fatigue, flexure, impact—Ductile or brittle
Pull testing—90° and 180° pull test, elongation at break, peel strength, butt joint, and lap-shear adhesion
Hot water baths—Used to condition absorber materials in hot water before being pulled on Instron 5500R
Sebastian Quad Pin-Pull—Adhesion or material-strength measurements (Sebastian quad, pin-pull, etc.)
Mocon Permatran W 3/31—Measures the amount of moisture that diffuses across polymers; blows dry air along one side of polymer membrane and humidified air along the other side, measuring the transient water-vapor transmission rate (WVTR); diffusivity, solubility, permeability of a tested polymer can be determined by fitting measurements to theoretical modules; measurements are made 20°C to 85°C, 100% relative humidity
Thermogravimetric analyzer—Directly measures water up-take in a sample to analyze water diffusivity in samples (in progress)
Mocon OxTran-100—Measures the oxygen transmission rate through synthetic film, coated papers, and other flexible or semi-rigid packaging materials; oxygen flows on one side of the barrier and an oxygen-free carrier gas flows on the other side, carrier gas conveys the oxygen that diffuses through the barrier to oxygen-specific coulometric detector; measurements are made ambient to 70°C, 0% to 100% relative humidity
TABER® Abraser (Abrader) Test—Measures abrasion resistance for accelerated wear testing
Rockwell or Vickers hardness testing—Tests sample hardness by applying force on a sample using a diamond stylus; measures the amount of indentation to calculate hardness
Thin-Film Deposition and Mechanical Characterization Laboratory (FTLB/158-02)
The FTLB/158-02 is well equipped with barrier deposition equipment; for more information, contact Cheryl Kennedy.
Vac-Tec DC&RF Sputtering—RF/DC Planar Magnetron deposits films of metals, conductors, oxides, and insulators by sputtering to form multilayered optical structures of the type used with solar systems (e.g., AR coating, mirrors, lenses, absorbers, light pipes, solid-state devices). Sputtering is a vacuum coating process where material is dislodged and ejected from the surface of a solid target; DC sputtering is used to deposit conducting materials, radio frequency 13.56 MHz is used to deposit non-conducting materials; three 5" x 8" planar magnetron guns, all compatible with DC sputtering and two compatible for RF sputtering; water-cooled substrate size is 5" x 8" or 5" x 20"
Pernicka 3-Chamber Vacuum Deposition System—Deposits films of metals, conductors, and insulators by evaporating and sputtering to form multi-layered optical structures of the type used with solar systems (AR coating, mirrors, lenses, absorbers, light pipes, solid state devices, etc.); three vacuum-coating chambers: load-lock, magnetron sputtering, and ion-assisted e-beam; sample size is 1' x 1':
Reactive Pulsed DC (or MF) Sputtering—Pulsed DC power prevents arcing on target surface during deposition of non-conducting films; the magnetron-sputtering chamber has three linear arrays of five Mini-Mac or two 3"x 12" planar magnetron guns capable of co-deposition
E-beam Evaporation—Deposits five materials sequentially and co-deposit two different materials simultaneously through electron-beam material evaporation and condensation
Ion Beam Assisted Deposition (IBAD)—Combines physical vapor deposition (PVD) with ion-beam bombardment to control film properties; dense, uniform, adherent, low-stress films of most coating materials on most substrates, including extremely adherent metal coatings on polymers
Accelerated Exposure Testing Laboratory (FTLB/158-03)
We use these temperature- and humidity-controlled chambers to test for weathering durability, corrosion on mirrors, delamination of polymers under controlled conditions, and other research. The conditions listed along with the equipment represent current tests. For more information, contact Mike Kempe.
Blue M Temperature/Humidity Oven (85°C, 85% relative humidity)
Bench-top Blue M temperature-only ovens (2)
Lab-line vacuum oven (85°C with nitrogen purge)
Q-Panel QUV—Thermal moisture cycles (UV at 50°C; dark cycle at 30°C with condensation)
Atlas CI-65—Accelerated weathering machine (1 sun, 60°C and 60% relative humidity)
Oriel 1000W Solar Simulator—Accelerated weathering machine (70°C, 70% relative humidity)
Oriel 1400W Solar Simulator—Accelerated weathering machine 8-chamber system; half exposed to UV light, the other half dark; can do four combinations of temperature (high or low) and relative humidity (high or low)
Atlas CI 5000—Accelerated weathering machine (2 suns or equivalent of six times outdoors; 60°C, 60% relative humidity)
Atlas Suntest Chambers (2)—Accelerated weathering chambers (1.3 suns, ambient relative humidity, 75°C, 40°C)
PV Module Encapsulation Research Laboratory, MERL (SERF/E216)
PC-based Analytical Instruments
The following computer-based instruments help us analyze samples.
Hewlett Packard 8452A Diode-Array UV-visible Spectrophotometer—Measures transmission or absorption of solution of film sample in spectral range of 190 nm to 820 nm with resolution of 2 nm
SPEX Fluorolog II Fluorescence Spectrophotometer—Measures emission or excitation spectrum of a material in the UV-visible spectral range with additional ability to do time-based or synchronized scans
HunterLab UltraScan Spectrocolorimeter—Measures/analyzes the color indices of a film sample either by transmission or reflection from 375 nm to 750 nm
HP 1090 LC Series II High-Performance Liquid Chromotography system (HPLC)—Analyzes organic or inorganic components of a sample using either UV or electrochemical detector; has auto-sampling capability
CHI660 Electroanalytical Workstation: Performs a number of electrochemical analytical tests to analyze/quantify electroactive components in solutions:
Sweep—Cyclic, linear, rotating disk voltammetry with Tafel plots
Step—Chronoamp and chronocoulemetry, staircase voltammetry, Tast polarography, differential or normal pulse volt and polarography, square wave voltammetry
AC—Volt and polarography (phase selective or 2nd harmonic); impedance spectroscopy with time base
Stripping—Linear, differential pulse, normal pulse, square wave, and AC (standard, phase-selective, and 2nd-harmonic); stripping voltammetry
Controlled Current—Chronopotentiometry (standard and with current ramp); potentiometric stripping analysis
Other techniques—Amperometric I-t curve, differential-pulse amperometry, double-differential pulse amperometry, triple-pulse amperometry, bulk electrolysis with coulometer, hydrodynamic modulation voltammetry
Keithley 6517A Electrometer—Measures electrical resistance/conductivity of highly resistive film materials such as polymeric PV encapsulant films
Keithley 485 Picoammeter—Measures low-level electrical currents
Sample Preparation Equipment
The equipment described below aids in sample preparation.
U.S. Stoneware Roll Mill—Blends or roll-mixes polymer pellets with formulation additives using controllable speed
Carver Model 3393 Lab Press/Watlow Series 981 Temperature Controller—Thermal pressing or treatment of film samples
C.W. Brabender Bench-top Film Extruder—Used to extrude polymeric encapsulant films from the formulated polymer pellets that are developed and tested as new encapsulant films
C.W. Brabender Polymer Extrusion System—Heats and extrudes polymer encapsulant films from formulated polymer pellets; achieves controlled thicknesses; used to prepare new films for testing
Custom-Built Double-Bag Vacuum Laminator (Astro Power LM-404)—Laminates solar cell devices (glass/encapsulants/backing materials) and cures encapsulant films for lab-scale specimens up to 16" x 16"
Accelerated Exposure Systems
We use these temperature- and humidity-controlled chambers to test samples under simulated and accelerated conditions.
Oriel 1-kW Solar Simulators (4):
UV Solar Simulators (2)—Accelerated exposure of samples in UV range to 450 nm with an integrated 300 to 400 nm intensity of 5 UV suns
Full-spectrum Solar Simulator—Xenon arc; exposure in UV-visible to IR range with integrated 300 to 400 nm intensity of 5 to 7 UV suns; light-exposing area is 6" x 6"
Light source—Condensable light beam for variable intensity
DSET 1.8-kW Suntest Table-top Exposure Chambers (2)—Exposure of samples under an intensity of 1 to 1.2 UV suns
Atlas Ci4000—Xenon arc accelerated environmental weathering chamber (6,500 cm2 exposure area, 2-sun irradiance, 40° to 115°C, 10% to 75% relative humidity, simulated rain/condensation sprays
The equipment described below rounds out the capabilities of the laboratory.
Nikon 74313 Microscope and Micromanipulator Model 6000—Microscopic digital imaging system; can conduct four-probe potential-current measurements; aids in examinations/imaging of sample defects on a microscopic scale through video and recording; this system is in progress and still lacks a relay lens and imaging board
Omnimark Mark 4 Moisture Analyzer—Quantifies water content in samples using thermal heating methods
- Denver Instrument A-200DS analytical balance
- Mettler top-load balance
Orion pH Meter—Measures solution pH or conductivity
Rame-Hart Goniometer—Measures contact angle
IKA KS-250 Mechanical Shaker—Used to prepare samples, mix solutions, extract solvents
Lab-Line Duo-Vac and Squaroid Duo-Vac ovens—Controlled ovens for dark sample exposure at elevated temperatures; useful for contrasting/comparing dark/heat vs. light/heat stress effects; dries sample preparations with or without vacuum
Branson 3510 Ultrasonicator—Used in preparing samples and cleaning glassware
- DC Power Supplies—For voltage supply and current output control:
- Kepco BOP-36-6D Electrical Bipolar Op-Amp—Power supply and amplifier
- Keithley 6438B—Power supply (0 to 60 V, 0.5 A with limits)