In the practical application of PV modules, shading is a common issue. The resulting revenue losses and safety hazards have long plagued the industry, casting a shadow over the development of PV. Thanks to its unique design, BC cells have innovatively addressed this industry pain point, achieving a balance between PV safety and power generation efficiency.
Drawbacks of Conventional Cells
The power reduction and localized overheating under shading are caused by the inherent structure of conventional cells. Most conventional cells adopt a double-sided structure, with positive and negative electrodes on opposite sides, forming fixed current transmission paths.
When part of a cell is shaded, the shaded area cannot absorb light energy to generate current normally. At this point, the current produced by other normally operating areas in the string is forced to pass through the shaded region—a high-resistance zone with no photo-generated carriers or internal electric field. This converts substantial energy into heat, triggering localized overheating. Meanwhile, the current transmission path of the entire string is disrupted, leading to a sharp drop in power or even a complete shutdown.
Soft Breakdown in BC: The Perfect Solution
BC cells possess inherent structural advantages. Their back-contact design fundamentally changes the current transmission path. By uniformly integrating soft breakdown structure into BC cells, they gain core strengths in shading resistance and anti-localized overheating, becoming a technical highlight different from for conventional cells to replicate
Simply put, soft breakdown provides each BC cell with a flexible current bypass channel. This design ensures that the BC cell consumes no power and does not interfere with normal generation when the cell is fully illuminated. When shading occurs, it activates immediately to divert current and prevent energy accumulation and overheating.
The small amount of heat generated by shading does not concentrate or accumulate locally; instead, it dissipates across the uniformly distributed soft breakdown structures. This reduces overall heating power and achieves uniform heat dissipation, suppressing localized overheating at the source.
As a result, BC modules show significant advantages over conventional modules under shading:
Localized overheating: Conventional modules concentrate heat in the shaded area, with local temperatures soaring to 100–200°C, easily causing burnout or fire. In BC modules, heat does not accumulate at shaded spots, and measured peak overheating temperatures are reduced by more than 30% compared to conventional modules.
Power performance: Shading on a single conventional cell causes a drastic power drop for the module. The soft breakdown structure in BC cells prevents current interruption, resulting in a much lower power loss from shading compared to conventional modules such as TOPCon.
In summary, targeting the pain points of shading and localized overheating in conventional cells, BC cells innovatively integrate a soft breakdown structure. This not only fundamentally resolves localized overheating but also significantly reduces power losses caused by shading.
BC cells completely eliminate the safety risks of burnout and fire associated with localized overheating in conventional cells, ensuring stable power generation of power stations even under complex shading conditions. This technological breakthrough delivers dual guarantees of safety and efficiency, aligning with the core demands of large-scale, high-quality development of PV power plants. It points the way for the sustainable upgrading of the PV industry and facilitates a sound development pathway that is safe, efficient, and profitable.
