A thin strip of copper and aluminium in solar panel called a busbar is an integral element of photovoltaic module.
Conducting the current
Solar cell busbar conducts electricity from solar photons to the solar inverter. Then the current gets converted from direct into alternate one.
Busbars are usually flat which allows to dissipate heat more efficiently due to high surface area to cross-sectional area ratio. The size of the busbar is determined based on the maximum amount of current that can be safely carried.
How it’s done?
Busbars are connected by welded connections. Usually they are contained inside switchgear or busways. They are typically contained in busways with long busbars contained in protective coverings. This arrangement allows new circuits to branch off anywhere along the route of the bus way, creating multiple points along of transmission along the solar array.
Why modules have 2 or 3 busbars?
Some modules have 2 and some 3 busbars per solar cell. Three solar cell busbars increase the module’s effficiency since they can collect more charges since the resistance is lower. At the same time they produce shading and reduce active surface to convert photons. There is no exact anwer whether modules should have 2 or 3 busbars.