Thin rectangular shaped strips printed on the front and back of a solar cell are used to metallize crystalline silicon solar cells. Busbars are the name given to these front and rear contact strips. Conducting the direct current generated by the solar cell from the incoming photons is an important function of solar busbars.
Busbars are slender wires or ribbons that go down each cell of the solar module and carry the electrons (current) through it. On the front and back of a silicon solar cell, tiny strips are printed to metalize it. Busbars are the name given to these front and rear contact strips.
Busbars in solar cells are used to transfer the electric DC power produced by the cell when photons strike it. The busbars and fingers that make up these contacts are printed onto the surface using a process known as screen printing.
How are Busbars made?
Busbars for solar cells are typically constructed from high conductivity materials like silver paste. The front side’s current conductivity must be improved through silver plating in order to prevent oxidation (rear side).
The metallic, ultra-thin grid fingers that are perpendicular to the busbars are joined by the busbar. In essence, the fingers gather the produced DC current and send it to the busbars.
String and tab wires are soldered to the busbars during the module manufacturing process to link solar cells in a series and parallel configuration. The solar junction box is next attached to the collection of strings.
Finding the ideal balance between shading and reflection losses, which are caused by using too many contacts on the cell surface and essentially blocking light from entering the solar cell, and busbar and finger resistance losses, which are caused by using too few metallic contacts and resulting in greater distances between them, is crucial in the design and production of solar cells.
The height and width of the busbars, the width of the fingers, the distances between the fingers and the busbars, the type and quality of the metal, and other factors are crucial in this respect.
How many busbars were used in solar cells previously?
A previous standard called for solar cells to contain two busbars, on average. However, the busbar count in the majority of solar cells was increased to three busbars as technology advanced and the industry went toward higher efficiencies. The most recent trend is to include 4 busbars, and occasionally even 5 busbars, to reach even better efficiency.
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Due to the closer spacing between the busbars, the increased busbar count minimizes internal resistance losses. Additionally, they have improved the cell efficiency, which in turn has improved the module efficiency.
Even though there are more busbars, the solar cell is shaded more, yet multi-busbar cells still perform far better overall than traditional 2BB or 3BB cells. This is due to factors including the shorter effective finger distance between busbars, which lowers finger resistance losses.
In conclusion, a multi busbar (such as 4BB or 5BB) cell has even superior long-term dependability and performance compared to ordinary 2BB and 3BB cells.