Korean researchers build vertical solar panels with low reflection losses

A group of researchers from Korean conglomerate Hyundai Motor Group and Kyung Hee University developed a new vertical solar module concept for applications in existing outdoor structures or in urban areas where land availability is limited.

“This concept is a technology that increases the amount of sunlight incident without internal change of solar cell,” the research's lead author, Byunghong Lee, told pv magazine. “The biggest advantage of this technology is that it's not expensive because it can be applied to commercialized polyethylene terephthalate (PET) films.”

The panels are equipped with microprism-imprinted polyethylene terephthalate (PET) sheets that reportedly reduce reflection losses while upholding a transmittance exceeding 99%. The microprism array is imprinted onto a PET sheet using the roll-to-roll embossing technique.

“This method allows for the scalability of microprism sheets to larger dimensions, even up to meters, while maintaining accurate replication of the microprism morphology,” the scientists explained, adding that the sheet was then attached to the module via an adhesive index-matching gel.

The group built an experimental module with solar cells from Singapore-based manufacturer Maxeon and simulated its performance in real-world conditions in Uiwang, South Korea. The device was exposed to direct sunlight, which follows a straight path from the sun to the cells, and scattered sunlight, which is diffused by atmospheric particles and clouds.

The analysis showed that the module can achieve higher power generation levels compared to conventional modules mounted vertically, attributed to the omnidirectional antireflection characteristics of the microprism sheet.

“The measured results revealed a consistent trend of enhanced energy generation with the microprism sheet during the extended testing period,” the academics said. “The developed microprism sheet shows promise for preserving pristine PV performance against the influence of weather-related factors. During the testing period, we did not observe any degradation related to soiling.”

According to the research team, the microprism sheet has a reflectance below 0.01, which shows it has better omnidirectional antireflective properties compared to traditional single-layer and multilayer antireflective coatings. “Indoor and outdoor testing confirmed that the microprism sheet can contribute to the energy harvesting of upright SPs in any installation location throughout the year,” it concluded.

The novel concept was introduced in the paper “High-efficiency upright solar panels with antireflective microprism-imprinted sheets,” published in Cell Reports – Physical Science. “To further validate the impact, long-term outdoor testing across various locations at distinct latitudes is required,” the scientists said, referring to future work they want to undertake to improve the proposed technology.