Turn the research question into a test campaign
The February 2025 IEA PVPS review of degradation and failure modes identifies unresolved reliability questions for emerging perovskite technologies. Its public summary cautions that proposed solutions have not all been evaluated together in a single process.
For project evaluation, this raises a practical question: what should an outdoor campaign measure before a tandem-module claim becomes useful to a buyer? The answer requires operating records as well as an initial efficiency result.
Identify the sample and measurement boundary
Record the absorber combination, active and total areas, encapsulation and electrical connections. A research cell, a mini-module and a commercial-format module have different boundaries. Their results should not be combined into one record simply because each uses the word tandem.
Keep the initial stabilized power measurement and its conditions with the sample record. If the construction changes during the campaign, document the new version and the interruption rather than treating the sequence as one unchanged device.
Collect the conditions needed to interpret output
Log irradiance, module temperature and the relevant weather channels alongside electrical output. Tandem devices can respond to the distribution of light across wavelengths, so the spectral assumptions and available measurements deserve explicit review.
Specify sensor calibration, timestamps and missing-data treatment. A reference module can help explain conditions, but a different spectral response means its output cannot automatically correct every change in the tandem sample.
Distinguish measurement from operating strategy
State whether the sample was held near its maximum-power point, periodically swept or operated under another regime. The operating method affects what the measured energy represents. Record outages, maintenance and changes in the measurement equipment.
Report power retention and delivered energy separately. An outdoor energy difference can reflect weather, tracking quality or downtime as well as a change in the device, and those effects need to be investigated before assigning a degradation rate.
Publish a campaign that another team can interpret
A useful field update includes sample count, locations, seasons observed and the comparison method. Identify excluded intervals and uncertainty. The dataset should show how the reported result follows from the monitored equipment and operating boundary.
This measurement focus complements materials-stability research. Neither a short outdoor campaign nor an accelerated test independently establishes a universal service life, while a well-documented campaign can make the next development decision more concrete.
Frequently asked questions
Is peak efficiency enough to predict outdoor energy?
No. Weather response, operating method, availability and the actual module construction also affect energy.
Can a reference silicon module correct every tandem measurement?
No. Differences in spectral and temperature response need explicit consideration.
Does a short field campaign establish a fixed lifetime?
No. Keep the observation period and measured result separate from any lifetime model.
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