A ribbon for connecting back contact cells, the ribbon comprising: an elongated body; and a plurality of first extensions and a plurality of second extensions, respectively located on two longitudinal sides of the body in a width direction, wherein each first extensions is suitable to form a solder joint with one of the back contact cells and each second extensions is suitable to form a solder joint with an adjacent back contact cell; wherein each of the plurality of first extensions extends outward from a first longitudinal side of the body; each of the plurality of second extensions extends outward from a second longitudinal side of the body; and the plurality of first extensions and the plurality of second extensions adjacent to each other are staggered from each other in a width direction of the body; characterized in that: the body comprises a plurality of sets of slits, wherein: an end of each slit in each set of slits forms an opening on a longitudinal side of the body, and each slit extends in parallel to a width direction of the body; the plurality of sets of slits comprises a plurality of first set of slits and a plurality of second set of slits; each first set of slits is disposed on the second side of the body and opposite to one first extension, wherein the distance in a width direction between each slit in the each first set of slits and the one first extension is increased as the distance in a length direction between the slit in the each first set of slits and the one first extension is larger; and each second set of slits is disposed on the first side of the body and opposite to one second extension, wherein the distance in a width direction between each slit in the each second set of slits and the one second extension is increased as the distance in a length direction between the slit in the each second set of slits and the one second extension is larger. an elongated body; and a plurality of first extensions and a plurality of second extensions, respectively located on two longitudinal sides of the body in a width direction, wherein each first extensions is suitable to form a solder joint with one of the back contact cells and each second extensions is suitable to form a solder joint with an adjacent back contact cell; each of the plurality of first extensions extends outward from a first longitudinal side of the body; each of the plurality of second extensions extends outward from a second longitudinal side of the body; and the plurality of first extensions and the plurality of second extensions adjacent to each other are staggered from each other in a width direction of the body; an end of each slit in each set of slits forms an opening on a longitudinal side of the body, and each slit extends in parallel to a width direction of the body; the plurality of sets of slits comprises a plurality of first set of slits and a plurality of second set of slits; each first set of slits is disposed on the second side of the body and opposite to one first extension, wherein the distance in a width direction between each slit in the each first set of slits and the one first extension is increased as the distance in a length direction between the slit in the each first set of slits and the one first extension is larger; and each second set of slits is disposed on the first side of the body and opposite to one second extension, wherein the distance in a width direction between each slit in the each second set of slits and the one second extension is increased as the distance in a length direction between the slit in the each second set of slits and the one second extension is larger.