ASTM E1171 Standard Test Methods for Photovoltaic Modules in Cyclic Temperature and Humidity Environments

Get Certified ASTM E1171 Testing for Reliable Photovoltaic Module Evaluation

ASTM E1171 is a standard for testing photovoltaic modules in controlled temperature and humidity environments, and it is used by manufacturers, engineers, technicians, and suppliers. Testing can detect physical changes, changes in electrical performance, and weaknesses in module materials or interconnections. Results help identify how modules respond to simulated environmental stresses and whether they need further evaluation. ASTM E1171 evaluations may support product development, reliability assessment, quality control, and documentation of environmental performance. The required evaluation depends on the module construction, selected environmental procedure, test duration, electrical measurement requirements, and other conditions stipulated by the purchaser and manufacturer.

• Photovoltaic Modules: Evaluating modules exposed to simulated temperature and humidity conditions.
• Thermal Cycling: Subjecting modules to repeated temperature changes while applying an electrical forward-bias current.
• Humidity-Freeze Cycling: Exposing modules to alternating humid and freezing conditions to evaluate environmental stress.
• Damp Heat Exposure: Applying extended exposure to elevated temperature and humidity to assess material degradation.
• Electrical Biasing: Applying a forward-bias current during thermal cycling to stress module interconnections and solder bonds.
• Module Mounting: Supporting modules so that they remain electrically isolated and allow free air circulation around their front and back surfaces.
• Electrical Evaluation: Measuring electrical performance before and after environmental exposure.
• Visual Inspection: Examining modules for physical changes, defects, or other visible effects after testing.
• Reporting: Recording environmental conditions, test duration, electrical measurements, visual observations, and any deviations from the procedure.

What are the Uses of ASTM E1171 Testing?

ASTM E1171 is used by manufacturers, technical personnel, operators, and engineers to assess PV module responses to simulated temperature and humidity environments. The method can be used for environmental stress assessment, product development, and manufacturing quality control. The ASTM E1171 standard:

• Describes testing procedures for PV modules under simulated environmental conditions.
• Assists in assessing module performance during thermal cycling.
• Assesses the module’s response to humidity-freeze cycling.
• Helps determine the effects of extended damp heat exposure on module materials.
• Assists in assessing whether electrical performance changes after environmental exposure.
• Assists in detecting physical changes that may not be apparent from electrical measurements.
• Electrically biases module interconnections and solder bonds to evaluate the effects of stress.
• Provides data for comparing module responses to different environmental procedures.
• Assists in product development and environmental reliability assessment.
• Supports documentation of module condition and performance changes for quality control and traceability.

Which Materials Can Be Tested Under ASTM E1171?

ASTM E1171 applies to PV modules, not individual raw materials or isolated components. These modules may comprise crystalline silicon and other PV technologies intended for terrestrial use. The method applies to modules with varying encapsulants, backsheets, front covers, cell interconnections, junction boxes, and frame constructions. Technicians and engineers review the module configuration, determine the necessary electrical connections, and install representative modules for environmental exposure. The method assesses the impact of simulated temperature and humidity conditions.

Why is ASTM E1171 Important?

ASTM E1171 is significant because it provides consistent methods for assessing PV module responses to simulated temperature and humidity stress. Modules are subjected to a series of controlled environmental cycles, and their electrical performance and physical changes are measured before and after exposure. The method assists in detecting degradation of module materials, interconnections, and solder bonds that may affect long-term module performance. It can also be used to compare module designs and environmental test conditions. However, when evaluating module suitability for a given application, engineers must also consider field conditions, electrical performance, material properties, and other relevant reliability evaluations.

ASTM E1171 Testing Process and Data Collection

The ASTM E1171 evaluation process starts with a review of the PV module construction, environmental test requirements, and selected procedure. Technicians select representative modules, document their initial condition, and conduct the necessary electrical measurements and visual inspections. They then place the modules in a controlled environmental chamber and subject them to thermal cycling, humidity-freeze cycling, or extended damp-heat exposure. During thermal cycling, technicians cycle the module temperature while applying the specified forward-bias current to simulate electrical stresses on module interconnections and solder bonds. They then conduct the required electrical measurements and visual inspections after exposure to identify physical and performance changes. Environmental data, electrical data, test duration, and visual observations document module responses and support further investigation if degradation is observed.

Common Challenges and Troubleshooting

The challenges in ASTM E1171 evaluation include environmental chamber stability, module mounting, electrical biasing, sensor accuracy, and measurement consistency. Temperature and humidity exposure can be uneven due to inconsistent airflow or improper sensor placement. The stress applied during thermal cycling can also be affected by incorrect electrical connections or bias-current settings. Initial and final electrical measurements may differ, and measurement inconsistencies can obscure the effects of environmental exposure. Technicians should check chamber calibration, module mounting, electrical connections, sensor placement, and measurement equipment before recording the results. When exposure results indicate unexpected changes in electrical values or visible damage, engineers should carefully examine the exposure records, bias-current conditions, measurement procedures, and module inspection results before determining whether further testing is needed.

• Technicians record the module identification, construction, initial electrical characteristics, and test conditions.
• Environmental records include temperature, humidity, cycling conditions, and exposure time.
• Electrical measurements identify performance changes in the modules after environmental stress.
• Visual inspection may detect cracks, discoloration, corrosion, and other physical changes.
• Thermal cycling results help evaluate how electrical biasing affects module interconnections and solder bonds.
• Engineers evaluate physical and electrical changes at the same time. Visible damage can occur without apparent electrical changes, and electrical degradation can occur without visible changes.
• The final report includes test conditions, electrical results, visual observations, deviations, and other relevant data for evaluating module responses.

Link to ASTM E1171