Grid Based Backsheets

Transparent Backsheet With Grid Enhances The Efficiency Of Bifacial Modules By Providing Optical Gains Similar To Monofacial Modules

Grid Based Backsheets

Optical illusion: Applying grid on a backsheet leads to an optical illusion – a white reflective grid (left) on a transparent backsheet mimics the monofacial appearance of the modules, while a black grid on a white backsheet offers an all-black look. (Source: Hangzhou First)

  • Transparent backsheet with grid is an innovative solution to enhance bifacial module efficiency by incorporating a printed white reflector grid on inter-cell spacing areas
  • Custom made backsheets tailored to different cell sizes and modules designs, with an additional cost of approximately 10% compared to transparent backsheets
  • Leading backsheet companies offer transparent backsheets with grids, which are widely accepted but face challenges with cell alignment.

 

In our previous article we discussed about the growing interest of transparent backsheet and shares of leading backsheet suppliers in the market (see Technology Trends In Backsheet Segment). In this article we look into further grid based backsheet structures and challenges and opinions from several market leaders.

Bifacial as a technology comes with one inherent limitation – the front power of the bifacial module is less than that of its monofacial variant. The inter-cell spaces of a monofacial module are white, which reflect the light hitting these spaces onto the active surface, enhancing optical gains. Bifacial, with its transparent rear cover, lets the incident light on these inactive areas to simply pass through, thus missing out on any such gains. To overcome this hurdle, backsheet makers borrowed an idea that was initially introduced by the solar glass segment.

Backsheet makers are offering a tailored product that remains transparent in those areas where the cell will be placed and the inter-cell spacing area is printed with a white reflector. Such backsheets are referred as “grid” and/ or “patterned”. This way, a bifacial module looks like a monofacial panel from both the sides and the white reflector assumes the role of reflecting incident light on the inter-cell spacing. All major companies are offering such custom-made backsheets tailored to match the different cell sizes and module designs of individual manufacturers. The additional costs for applying the grid are about 2 RMB/m2 to 3 RMB/ m2, or about a 10% premium over the price of transparent backsheet.

While several backsheet suppliers say that such products are widely accepted, there are some concerns too. Alignment of cells into the predefined areas is not easy. The main issue here is that the backsheet is typically moving or shifting, which has to be avoided to retain the alignment of cells into the predefined areas. The backsheet cutting machine also needs to be modified in order to cut the backsheet with very high precision. To put it simply, it requires a high level of automation, meaning it is difficult to attain reasonable production yield with semi-automatic or manual lines.

Thus, the approach has not taken root in places like India, according to Cybrid’s International Marketing Director Eric Yang, while a few Chinese producers are in mass production with the technology. It also comes with the risk of scratches on the grid during transportation, according to Lucky Film. On the other hand, companies like Crown and Jolywood say the transparent backsheet with grid has higher acceptance than the standard one; the former even says that up to 80% of the transparent backsheet sales are with grid.

The article is an excerpt from the TaiyangNews Market Survey on Backsheets and Encapsulation 2022-23, which can be accessed free of charge here.

About The Author

Shravan Chunduri

HEAD OF TECHNOLOGY Shravan is a name to reckon with in the solar industry. Having caught the solar bug very early in his career, he began his journey 20 years ago in research, followed by stints in solar manufacturing. He then moved on to write and eventually ventured into Consulting. At TaiyangNews, he is responsible for drafting the technology reports and articles that are regularly published in TaiyangNews, apart from hosting the Conferences and Webinars that TaiyangNews conducts. [email protected]

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