The world’s first full-size interdigitated back contact (IBC) bifacial solar module has been developed and fabricated in Singapore by the Solar Energy Research Institute of Singapore (SERIS) at the National University of Singapore (NUS) in collaboration with the International Solar Energy Research Center Konstanz, Germany (ISC Konstanz).
The module technology’s first prototype was produced using bifacial ZEBRA IBC solar cells from ISC Konstanz with efficiencies as high as 22%. The cells were fabricated using industrially proven process equipment and standard industrial 6-inch n-type Cz monocrystalline silicon wafers. The module’s structural reliability is ensured by using a double-glass insulation technique perfected by SERIS since 2009. Encapsulated using the double-glass structure, IBC bifacial solar modules could offer a longer warranty period of 30 years or more. Furthermore, by utilising the bifacial nature of the solar cells, as much as 30% extra power is generated by the double-glass module due to reflection of sunlight from the ground (‘albedo’) towards the module’s rear surface.
Dr Wang Yan, Director of SERIS’ PV Module Cluster, is ecstatic about this new product. “With SERIS’ new module design, panels with 350 Watts front-side power can be made with sixty 23% efficient screen-printed IBC cells. Considering an additional 20% of power via the panel’s transparent rear surface, each 60-cell IBC bifacial solar module will produce a stunning 400 Watts of power in the real world.”
The world’s first full-size IBC bifacial module has several unique features:
- All back contact: This eliminates metal shading losses from the cells’ front surface. As a result, the module can achieve higher current and efficiency outputs.
- Bifacial nature: The module is able to absorb light from both its front and rear surface, with a bifaciality of 75%. This enables the module to convert sunlight that enters via its rear surface, as a result of reflection from the ground and the surroundings.
- Double-glass structure: The cells are encapsulated between two glass panes using polyolefin elastomer (POE), which guarantees a long module lifetime in the field.
- Low-temperature interconnections: This prevents warping of the IBC cells due to heating.
- Specially designed & customized electrical junction box: This prevents shading of the rear surface of the bifacial IBC cells.
- Industrially feasible solar cell and module fabrication process and equipment: This enables the module to achieve high efficiency at lower cost and means that the technology is ready for industrial production.
Dr Radovan Kopecek, founder of ISC Konstanz, Director of Advanced Solar Cells and Lead Scientist for ZEBRA development since 2009, has ambitious future plans for this technology: “Many people now might think that putting highly efficient IBC cells into bifacial modules does not make sense – but our consortium will prove them wrong. The ZEBRA process is extremely simple and cost-effective and so is the module manufacturing process. In large bifacial systems, this technology will lead to the lowest LCOEs ever. Bifaciality is quickly gaining popularity and, since a few weeks ago, one can also simulate the bifacial advantage using PVsyst – such developments will give many bifacial technologies the breakthrough in the PV systems arena”.
Prof Armin Aberle, SERIS CEO, is also enthusiastic about the development. “IBC cells are famous for their efficiency, reliability and durability in the field. The newly developed IBC bifacial module is a testimony of SERIS’ R&D capabilities in the PV module technology sector. The module technology offers world-class front side power while providing free extra power from the rear side. As a result, it has excellent LCOE potential” he explained. “The prototype module made at SERIS serves as a proof of concept for mass production. The next step will be to transfer the technology to industrial partners.” He believes that such a high-power product could be available in the market within two years.