Abstract: A solar-cell piece and a solar-cell assembly, wherein the solar-cell piece includes a plurality of sub-cell-piece units and solder strips, wherein neighboring sub-cell-piece units are superposed, and are connected by the solder strips to form a cell string; and each of the sub-cell-piece units is provided with solder-strip containing slots in positions where the solder strips are located in superposed areas of a front face and a back face, and supporting structures are provided between neighboring solder-strip containing slots. The superposition between the supporting structures at the front face and the back face of the two neighboring sub-cell-piece units can reduce the height difference at the overlapping position, to disperse and release the stress between the neighboring cell pieces generated by the solder strip.