What is Busbar (MBB)?
Thin metal lines on a solar cell that collect and carry the current it generates; more busbars means lower losses.
Quick Answer
Most mainstream panels sold in the UK now use multi-busbar (MBB) cells for a small efficiency gain. Premium back-contact panels from Maxeon, Aiko and LONGi remove front busbars altogether, which is why they look uniformly black with no visible gridlines.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
Busbar (MBB) Explained
Busbars are the thin metallic strips printed across a solar cell that collect the electrical current and carry it to the panel's wiring. Older cells used 3 to 5 busbars; modern multi-busbar (MBB) cells use 9, 12, 16 or more, sometimes as fine round wires. More busbars shorten the path electrons travel, cutting resistive losses and improving efficiency, and they add redundancy if a cell develops a microcrack. Back-contact cells (IBC, ABC, HPBC) remove front busbars entirely by moving the contacts to the rear.
How Does Busbar (MBB) Work in the UK?
Most mainstream panels sold in the UK now use multi-busbar (MBB) cells for a small efficiency gain. Premium back-contact panels from Maxeon, Aiko and LONGi remove front busbars altogether, which is why they look uniformly black with no visible gridlines.
Frequently Asked Questions
What is a multi-busbar (MBB) solar panel?
A multi-busbar panel uses cells with many busbars (often 9 to 16 or fine round wires) rather than the older 3 to 5. More busbars reduce resistive losses and add redundancy against microcracks, giving a small efficiency and reliability gain.
Why do back-contact panels have no busbars on the front?
Back-contact technologies (IBC, ABC, HPBC) move all the electrical contacts to the rear of the cell. With no busbars shading the front, more of the surface captures light, which lifts efficiency and gives the clean all-black look.
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John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.