PV Panel Backsheets: Design and Performance

If you’ve looked into solar PV, you’ve probably heard words like “all-black”, “bifacial”, or “all glass”. These terms refer to what’s on the back of your PV panel. Backsheets matter because they affect the appearance and performance of your PV system. Read on to learn about the four types of solar panel backsheets.

White EVA

EVA (ethylene vinyl acetate) is a plastic material that goes on the back of your PV panel to seal against the elements. White is a good choice of colour in some settings because white surfaces reflect light. This reflected light gives your panels a slight boost in power output. White EVA was the most common option in the past but other options are now becoming more popular.

Black EVA

“All-black” solar panels use black EVA backsheets. These panels also come with black frames. The advantage of all-black panels is great aesthetics, which makes them popular for residential rooftop systems. The trade-off is that all-black panels produce a few percent less power than other kinds of panels. However, you can easily make up for this by adding one extra panel or using high-efficiency panels.

House with all-black solar PV panels on the roof.
Many people prefer the appearance of “all-black” solar PV panels, as shown above. Image credit: Vivint Solar on Pexels.

Transparent EVA (Bifacial)

Transparent backsheets are becoming ever more popular for two main reasons. The first is good aesthetics: Only your roofing material will be viable through the gaps between the cells. Secondly, transparent backsheets make it possible to generate extra power using the light that reaches the back of your solar panels.

To produce power from both sides, your solar PV panel needs to be made with special cells. In the past, these “bifacial” cells were much more expensive than standard cells. Fortunately, the technology has matured and bifacial panels are now highly cost-competitive. Bifacial panels are taking a bigger share of the market every year and may soon be standard.

All-Glass

All-glass have a second sheet of glass on the back in instead of EVA plastic. High-quality all-glass panels provide the best-possible seal against the elements. For this reason, all-glass panels are used in extremely demanding applications like maritime solar PV. All-glass panels also benefit from increased power output due to the bifacial effect and have excellent aesthetics. All-glass panels generally come with a moderate price premium compared to other types.

Conclusion

There are four types of PV module backsheet to choose from. Each one comes with its own pros and cons in terms of price, appearance, performance. Bifacial panels (whether all-glass or glass-EVA) have excellent all-round performance and might eventually become the standard option.

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