The increasing demand for high efficiency PV modules at lower costs of production leads to new designs of solar cells. For enhanced module efficiency, the cell efficiency must be optimized first to guarantee later operation under module conditions.
The number of busbars can be varied so as to decrease the total series resistance of the interconnected Solar cells. Also, a device with multiple busbars has a high cost saving potential due to the reduction in the metal consumption for front side metallization process. This led to the development of Multi Busbars for the PV module industry.
What is Solar cell busbar:
Silicon solar cells are metalized with thin rectangular-shape strips printed on the front and back sides of a solar photovoltaic cell. These metallic contacts are called busbars and have a significant purpose: they conduct the direct current generated by the solar photovoltaic cell. Frequently, solar cell busbars are constructed from copper, coated with silver. The silver coating is necessary to enhance current conductivity (front side) as well as to lower oxidization (rear side).
How Solar busbar works:
The fingers collect the generated current and deliver it to the busbars. Tab wires are soldered to the busbars to connect a string of cells and thus to collect the electric current of one cell string. Clusters of tab wired cell strings are connected in parallel by bus wires which then delivers the cumulative power from all the cells to the junction box.
Basically, the surface of a conventional solar cell is characterized by a grid of these fine, current-collecting and delivering fingers, and the current-conducting busbars. These contacts – the busbars and the fingers – are printed onto the surface via a technology called screen printing, a process which we introduced in an earlier article about solar cell production.
Solar busbar – development trends and future:
The most common solar cell design involves 2 or 3 full-line busbars printed onto the cell. You will nowadays still find the majority of all PV modules using such 3 busbar (3BB) cells as they are commonly abbreviated.
Since work on the improvement of existing solar cell technologies is becoming increasingly harder as researchers struggle to squeeze out more from conventional cells, and breathtaking, stable new solar cell technologies are still not in mainstream sight, an increasing trend in the industry is to re-think cell design and manufacturing to further increase efficiency and reliability.
What is Multi busbar cells:
Multi busbar cells, noticably 5 busbar (5BB) cells, are currently one of the major trends in solar cell and module design. This increased number of busbars reduces the internal resistance losses, which is due to the lesser distance between the busbars.
Different busbars in solar cell
Even though the higher quantity of busbars increases the shading of the solar cell, yet overall performance of multi busbar cells is much better than that of conventional 2BB or 3BB cells, because reduction of the effective finger length between the busbars, which reduces finger resistance losses, as well as the lesser impacts of micro cracks. As micro cracks typically occur between busbars, the impact of such cracks is thus reduced towards smaller affected cell slices between two busbars. Thus, as compared to conventional 2BB and 3BB cells, the long-term reliability of a multi busbar cell even in the event of micro cracks is higher.
With the advancement of the solar technology, EverExceed Solar Panels are also equipped with the advanced Multi BusBars technology to provide unparalleled efficiency along with greater performance warranty.
