Abstract: A planar conductor is cut along first, second, and third cutting lines. The first cutting lines extend in a direction orthogonal to the longitudinal direction of the planar conductor and cut the planar conductor into a plurality of busbars. The second cutting lines extend in the longitudinal direction of the planar conductor and along which every other joint portion of a plurality of joint portions is cut out at which the busbars are joined to the first linear conductors with an insulating cover material. The third cutting lines extend in the longitudinal direction of the planar conductor and along which a plurality of joint portions are cut out at which busbars other than the busbars to which the second cutting lines are set are joined to the second linear conductors with the insulating cover material.