Solar PV technology trends: Trends on cell geometry

Over the past decade, the solar industry has undergone significant changes, driven by technological advancements and innovations. One such trend is the evolution of solar cells’ geometric structure, which has resulted in the production of more efficient and powerful solar modules.

In this article, we’ll explore the drivers and benefits of the changing cell geometry and the potential risks associated with these trends.

Drivers and Benefits

Increasing Number of Busbars: One of the significant drivers of the changing cell geometry is the increasing number of busbars. Busbars are thin, flat metal strips used to connect solar cells. By increasing the number of busbars, the cross-sectional ribbon area can be reduced, allowing for a greater active cell area. This, in turn, leads to higher efficiency and reduced resistive losses. Additionally, the reduced ribbon area also means less silver metallization, resulting in cost savings.

Low-Temperature Approaches: Another driver is the increasing use of low-temperature approaches in solar cell manufacturing. These low-temperature processes future-proof for new cell technologies such as SHJ (Silicon Heterojunction) cells. By using low-temperature approaches, manufacturers can improve efficiency, reduce energy consumption during production, and decrease material costs.

Increased Efficiency: Changing the cell geometry also increases efficiency by increasing the active cell area and light reflection on wires. The reduced gap between cells or overlapping cells can also increase the efficiency of modules.

Potential Risks

Geometry Changes: One potential risk associated with changing cell geometry is the potential for mechanical stress or damage to the solar module. For instance, a module that uses a multiwire design may need a thicker encapsulant, increasing the risk of failure or damage to the module.

Process Changes: As the solar industry moves toward new components, such as structured foils, new reliability tests may be necessary to ensure their efficacy and durability. The use of these new components also requires process changes, which may increase manufacturing costs.

Shingled/Overlapping Cells: Shingled or overlapping cells are another potential risk associated with changing cell geometry. While these designs increase efficiency, they can also lead to higher stresses at the overlapping cell edge, increasing the risk of cell fracture or failure.

Cell Geometry Trends

To summarize the trends in cell geometry over the past decade, we can look at the National Renewable Energy Laboratory (NREL) reports. One significant trend is the increasing number of busbars in solar cells. According to the 2021 NREL report, cells with ten or more busbars have a global market share of 30%, which is expected to increase to 70% by 2032. Additionally, the report predicts that the use of busbars will extend to cells with a width of over 210mm by 2026.

Another trend highlighted in the NREL report is the increasing use of shingled cells or overlapping cells. In 2021, the market share of shingled cells was 9-10% for cells with a width of 161-166mm, but this is expected to increase to 80-90% by 2032.

The changing cell geometry is driving solar PV technology trends, resulting in more efficient, powerful, and cost-effective solar modules. The increasing number of busbars, low-temperature approaches, and overlapping cells are some of the significant drivers of this trend. However, changing cell geometry also presents potential risks, such as increased mechanical stress or damage to solar modules. As the solar industry continues to evolve, manufacturers must balance the benefits of new technologies with potential risks.