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What is Bus Ribbon?

Bus ribbon is a very specialized interconnect for photovoltaic modules.  Much like tabbing ribbon, bus ribbon is made of a copper ribbon or flat wire which is coated in solder.  The solder protects the surface of the copper from oxidation and provides a layer of solder to form a solder joint.  These solder-coated copper strips are used to channel current from the top and bottom of solar cells (tabbing/stringing) or to collect the electricity from these strings (bussing).

 

 

 

 

 

The main difference: bus ribbon is a bit wider, and sometimes thicker than tabbing ribbon.  You can think of tabbing ribbon as roads which travel across a solar cell, and bus ribbon as the highways that connect and tie them together.  Bus ribbon is larger in cross-section because it has more electrical current to carry.  To give you an idea of the size, bus ribbon is generally anywhere from 5mm-6mm wide, although some applications require bus ribbon more than twice as wide.

 

 

 

 

 

As bus ribbon becomes larger and larger, it is only natural to ask: "When will things need to change?"  When efficiencies and currents outgrow the physical constraints of bus ribbon, will module design change to meet the requirements?  Perhaps there will be a shift in the materials which are used instead – which would likely be even more expensive than a design change.  Either way, solder-coated copper bus ribbon has a long life ahead of it as the solar panel interconnection material of choice.