EN IEC 62788-2-1:2023/A1:2026

EN IEC 62788-2-1:2023/A1:2026 is a CLC amendment to the IEC measurement procedure for polymeric materials used as frontsheet and backsheet in photovoltaic modules. It updates the safety-related test language for these materials, especially the thermal exposure levels, UV weathering conditions, and the transmittance check used for frontsheets.

The amendment is written for people qualifying, testing, or specifying PV module materials - especially manufacturers, test laboratories, certification bodies, and quality teams. In practice, it tells them how to classify the thermal level, how to run FBST 08, and which post-exposure checks have to pass.

What does EN IEC 62788-2-1:2023/A1:2026 specify?

EN IEC 62788-2-1:2023/A1:2026 specifies amendments to the safety requirements and related measurement wording for polymeric frontsheets and backsheets used in photovoltaic modules. It centers on Clause 4, Clause 6.7.2, the definitions section, and the foreword and introduction.

The amendment organizes the work around:

• the safety focus for frontsheets and backsheets required by IEC 61730,
• the thermal rating concept based on module operating temperature,
• UV weathering by FBST 08,
• and a frontsheet optical durability check when IEC 61215-1 also applies.

What are the key requirements of EN IEC 62788-2-1:2023/A1:2026?

The amendment changes several technical points that matter when a material is being qualified for PV module use.

• Use “Level” with a capital L whenever the document names a defined thermal exposure certification protocol. This keeps the level designation consistent in test records and reports.
• Add temperature Level 0 for test sequences where [T98]max is 70 °C and all other tests follow the default settings in IEC 61730 and IEC 61215. This gives a clear baseline for the lowest operating-temperature class.
• Use the FBST definition as the front- or backsheet safety test in accordance with IEC TS 62788-2-1. This ties the abbreviation directly to the safety test family.
• Apply Clause 4 rating rules by maximum module operating temperature. The text links the front- or backsheet rating to the intended PV module operating temperature, which is the parameter buyers and labs need to match to the module design.
• Follow the revised FBST 08 UV weathering procedure in Clause 6.7.2. The test uses a xenon arc light source and different exposure patterns for frontsheets, backsheets, and materials qualified as both. In practice, this determines which side is exposed and for how long.
• Use Table 4 for UV exposure conditions. The table matches exposure options to rated module operating temperature and material type, and it distinguishes white/clear materials from black or colored ones. That means the laboratory has to choose the correct exposure condition before starting the test.
• Pass the post-exposure checks after UV and damp heat. Visual inspection, mechanical properties, and DC breakdown voltage remain the required evaluations, and frontsheets also need the transmittance retention check when they are qualified to IEC 61215-1. That gives a clear pass/fail set after ageing.
• Maintain more than 95% solar photon weighted transmittance for frontsheets when that additional qualification applies. For users, this is the optical durability control point.

What terms does EN IEC 62788-2-1:2023/A1:2026 define?

• Level 0 - A thermal exposure level for test sequences where [T98]max is 70 °C and the other tests use the default settings from IEC 61730 and IEC 61215.
• FBST - Short for front- or backsheet safety test in accordance with IEC TS 62788-2-1.
• T98 - The 98th percentile operating temperature used to classify the module operating condition.
• Frontsheet - The polymer layer on the sun-facing side of the PV module.
• Backsheet - The polymer layer on the rear side of the PV module.
• Absorbance A - The material property used to choose UV weathering conditions, with low absorbing materials identified in the amendment.
• Solar photon weighted transmittance - The optical performance metric used for the frontsheet retention check after ageing.

Who uses EN IEC 62788-2-1:2023/A1:2026?

EN IEC 62788-2-1:2023/A1:2026 is used by PV module manufacturers, polymer film suppliers, test laboratories, and certification bodies working on frontsheet and backsheet qualification. Quality managers and buyers use it to align material selection with the intended module temperature class and the required UV ageing evidence.

It is also relevant to engineering teams preparing test plans, because it tells them how to choose the UV condition, which side of the material to expose, and which post-test results must be documented.

What changed in EN IEC 62788-2-1:2023/A1:2026 from the previous edition?

EN IEC 62788-2-1:2023/A1:2026 is Amendment 1 to the 2023 document, and the amendment states these changes:

• “level” is capitalized as “Level” when it refers to the defined thermal exposure protocol.
• The foreword reference is corrected to IEC TS 62788-2-1.
• The introduction is expanded to mention an optical durability test for frontsheet transmittance anticipated by IEC 61215-1.
• The definitions section adds Level 0 and the FBST definition.
• Clause 4 is revised to align the rating text with Level 0, Level 1, and Level 2.
• Clause 6.7.2 is rewritten for FBST 08 UV weathering, Table 4 is updated, and the IEC TS 62788-7-2 reference is corrected.

Which standards are used with EN IEC 62788-2-1:2023/A1:2026?

• IEC 61730 - Provides the safety context for PV modules and the default evaluation framework used in the amendment.
• IEC 61730-1 - Gives the default module operating-temperature basis, including the Level 0 reference point.
• IEC TS 63126 - Defines the extended high-temperature operating levels used for Level 1 and Level 2.
• IEC TS 62788-2 - Supplies the UV weathering method referenced for FBST 08.
• IEC TS 62788-7-2 - Contains the UV test conditions A1 to A3 referred to in the revised UV weathering text.
• IEC 61215-1 - Provides the qualification context for the frontsheet optical transmittance retention check.

What does the EN IEC 62788-2-1:2023/A1:2026 document contain?

EN IEC 62788-2-1:2023/A1:2026 contains amendment text for the foreword, introduction, definitions, Clause 4, and Clause 6.7.2. It also updates Table 4 for UV exposure conditions.

The document gives the revised UV-weathering procedure, including which side of a frontsheet or backsheet is exposed, which exposure durations apply, and when a UV filter or special restriction can be used. It also identifies the post-exposure evaluations used for qualification and the transmittance retention criterion for frontsheets that also need to meet IEC 61215-1.