White EVA For Higher Module Output

• Replacing transparent EVA with white EVA results with an estimated power gain of about 1% to 2% is is the major trend in EVA segment
• White EVA is estimated to have a market share of 70% in monofacial module segment
• HIUV has developed a multilayered encapsulation with transparent and white EVA to have a softer product to be suitable for thin wafers

While EVA has been traditionally used in a transparent form for solar modules, a white variant was brought to the market to be used as the bottom encapsulation layer. The white EVA increases the light reflection from the cell gaps in a finished module, resulting in power gains. Replacing transparent EVA with the white variant on the module's rear side boosts the power output by up to 1%, whereas it could be up to 2% when using bifacial cells. Half-cell based modules can benefit even more due to a relatively lower packing density of cells in a module.

All this is not new, but white EVA is now becoming a mainstream product. About 70% monofacial modules today use white EVA on the rear side, according to Cybrid's Marketing Director Xinjun Li. However, in terms of sales and shipments, it has a market share of only 30%, because a solar module requires two films of EVA – one for the front and one for the rear; and transparent products are always the choice for the front side. Making white EVA has its implications on costs, thus also the price is higher – about 20% more expensive than the transparent variant (see Excerpts Of Trends In Encapsulation).

China's HIUV, claiming to be the inventor of white EVA, has made a few improvements in regard to processing thinner wafers. HIUV's Vice President Colin Quan explains the problem: The white EVA is slightly different from transparent EVA, in that it is a little harder, which creates stress at the cell edges and busbars during lamination. To counter this, HIUV has come out with a softer multi-layer structure called EWE or EW, where E stands for transparent EVA and W for white EVA. Simply put, the harder white layer is covered on one side or both by the softer transparent EVA to reduce the stress. "We are evaluating it with big module companies to optimize the composition and structure," said Quan (see A Few Lead The Encapsulation Segment)

The Text is an excerpt from TaiyangNews' recent Market Survey on Backsheet and Encapsulation Materials 2021, which can be downloaded for free here.

An overview of the survey was presented during TaiyangNews Conference on Reliable PV Module Design. To learn more about the conference and view the presentations click here.