An MBB solar cell is a type of photovoltaic cell that utilizes multi-busbars on its surface to improve efficiency and reliability compared to traditional designs.
Understanding Multi-Busbar (MBB) Technology
Traditional solar cells typically have 2 to 5 thick busbars running across their surface. These busbars collect the current generated by the cell's active area, which is initially gathered by thin "fingers."
The Multi-Busbar (MBB) approach is an advancement where the number of busbars is significantly increased, often ranging from 9 to 16 or even more, while making them thinner.
According to the reference, the multi-busbars (MBB) approach aims to reduce resistive losses by reducing the amount of current that flows in both the fingers and the busbars.
How MBB Reduces Resistive Losses
- Shorter Current Path in Fingers: With more busbars spaced closer together, the generated current collected by the fingers has a shorter distance to travel before being picked up by a busbar. Shorter travel distance means less resistance and therefore lower energy loss (I²R loss) in the fingers.
- Lower Current per Busbar: With the total generated current distributed among a larger number of busbars, the amount of current flowing through each individual busbar is reduced. Lower current also contributes to reduced resistive losses (I²R loss) in the busbars themselves.
This reduction in resistive losses leads to a higher power output for the solar cell and the resulting module.
Key Differences: MBB vs. Traditional Cells
Here's a simple comparison:
| Feature | Traditional Solar Cell (e.g., 5BB) | MBB Solar Cell (e.g., 9BB+) |
|---|---|---|
| Number of Busbars | Fewer (2 to 5) | More (9 to 16+) |
| Busbar Thickness | Thicker | Thinner |
| Resistive Losses | Higher | Lower |
| Finger Length | Longer between busbars | Shorter between busbars |
| Silver Usage | More silver paste per busbar | Less silver paste per busbar |
| Efficiency | Standard | Improved |
Benefits of MBB Technology
The adoption of multi-busbar technology offers several advantages for solar cell and module manufacturers and consumers:
- Increased Power Output: By minimizing resistive losses, MBB cells can generate more power from the same amount of sunlight, leading to higher module efficiency.
- Reduced Silver Consumption: Although there are more busbars, their reduced width often results in a net decrease in the amount of expensive silver paste required per cell, lowering manufacturing costs.
- Improved Reliability: With more busbars, if one or a few busbars are damaged or break, the current can still be collected by the remaining busbars, reducing the impact on cell performance.
- Enhanced Shade Tolerance: In partial shading conditions, the current flow paths are more distributed, which can help mitigate efficiency losses compared to cells with fewer busbars.
- Aesthetic Appeal: The thinner, more numerous busbars can sometimes appear less visually intrusive than thick busbars, which is a consideration for rooftop installations.
Practical Implementation
MBB technology requires precise soldering or connecting techniques due to the thinner busbars and the increased number of connections needed during module assembly. Advanced interconnection technologies like multi-wire soldering or conductive adhesives are often employed.
This technology has become a standard feature in modern high-efficiency solar panels across various cell types, including PERC, TOPCon, and HJT.
