5.1 Photovoltaic modules and components must be resistant to prolonged exposure to solar radiation, moisture and heat. Degradation of polymeric components, delamination at the encapsulant and other interfaces, and moisture ingress are among the degradation modes known to decrease the output of photovoltaic modules. IEC qualification standards for PV modules include tests intended to uncover whether solar ultraviolet radiation induced degradation may cause early-life failures. This practice provides general and specific guidance on performing tests that meet the requirements of the ultraviolet radiation conditioning exposures in the IEC qualification standards.4 Other protocols exist that may also conform to the IEC test requirements.

5.2 In the qualification test sequence, this UV preconditioning exposure is conducted prior to the thermal cycling and humidity freeze tests. These tests were included to replicate a delamination failure observed in modules.5

5.3 IEC exposure methods should not be considered as long term weathering tests. Exposure to moisture in the form of condensation or water spray is not a requirement of the UV exposure tests in IEC PV module qualification standards. Inclusion of moisture is typically a consideration in weathering tests.

5.4 Variation in test results may be expected when operating conditions are varied within the acceptable limits of this standard. In particular, reciprocity of degradation among varying irradiance levels should not be assumed. Consequently, no reference to this practice should be made without an accompanying report prepared in accordance with Section 9 that describes the specific operating conditions used.

5.5 Correlation between this practice and long term performance of PV modules in real-world installations has not been determined. Although experience has shown these methods are effective in screening for unstable materials and systems, it is unknown at this time if degradation due to prolonged solar ultraviolet exposure can be replicated by extending the time and energy dosage of the exposures described in this practice. The most effective use of this practice is as a comparative tool for evaluating materials and systems. Consequently, the use of controls or reference materials of known performance is recommended; refer to Practice G151, Section 6.2.4.

1.1 This practice covers specific procedures and test conditions for performing ultraviolet conditioning exposures on photovoltaic modules or mini-modules using fluorescent ultraviolet lamps in accordance with Practices G151 and G154. This practice covers test conditions that meet the requirements for UV preconditioning in initial qualification tests of photovoltaic modules or mini-modules as published in International Electrotechnical Commission (IEC) standards.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.