What is BS EN IEC 62788‑6‑2 about?
BS EN IEC 62788‑6‑2 is a part of a multi-series standard that deals with the performance qualifications of materials used in photovoltaic modules.
BS EN IEC 62788‑6‑2 provides methods for measuring the steady-state water vapor transmission rate (WVTR), water vapor permeability (P), diffusivity (D), solubility (S), and moisture breakthrough time (Ƭ10) (defined as the time to reach 10 % of the steady-state WVTR) for polymeric materials such as encapsulants, edge seals, front-sheets and back-sheets.
BS EN IEC 62788‑6‑2 gives specifications for test procedures, such as terms, definitions, symbols, apparatus for carrying test procedures, preparing test specimens, calculations, stating the test reports, etc. for verifying the moisture permeation properties of polymeric materials.
Note 1: BS EN IEC 62788‑6‑2 is best applied to monolithic films. If multilayer films are used, the D and S values are only apparent values, but the steady-state values can still be measured.
Note 2: BS EN IEC 62788‑6‑2 is written for the measurement of water permeation, but it can equally be used for other permeants such as O2. In this case, the same diffusion equations, fitting procedures, and scaling arguments are used.
Who is BS EN IEC 62788‑6‑2 for?
BS EN IEC 62788‑6‑2 on moisture permeation properties of polymeric materials is useful for:
- Manufacturers and suppliers of photovoltaic (PV) devices
- Dealers and importers of photovoltaic (PV) devices
- Testing houses/ service providers of photovoltaic (PV) devices
- Entities dealing with photovoltaic (PV) devices
Why should you use BS EN IEC 62788‑6‑2?
The International PV Quality Assurance Task Force (PVQAT) leads global efforts to craft quality and reliability standards for solar energy technologies. The degradation of PV modules is known to go through many different corrosion processes. These degradation processes may depend upon moisture ingress into the encapsulant, edge seal, front-sheet, or back-sheet materials.
BS EN IEC 62788‑6‑2 describes methods to measure the permeation properties of polymeric materials. Typical polymeric materials used include (amongst other polymers) ethylene-vinyl acetate (EVA) and polyolefins for encapsulants, polyisobutylene (PIB) for edge seals, and polyethylene terephthalate (PET), polyvinyl fluoride (PVF), or polyvinylidene fluoride (PVDF) for back-sheets.
Hence, BS EN IEC 62788‑6‑2 helps you verify the moisture permeation properties of polymeric materials, which helps you in module design. These properties can be determined as a function of temperature and relative humidity. With these parameters, simple scaling rules for time and distance can be used to extrapolate to the user environments.
BS EN IEC 62788‑6‑2 could help you to quickly assess a solar photovoltaic (PV) module's performance and ability to withstand weather stresses, thereby reducing risk and adding confidence for those developing products, designing incentive programs, and determining private investments.
