"FIG. 18A is a plan view of the photovoltaic element as seen from its light-receiving surface side, andFIG. 18B is a sectional view of the photovoltaic element shown in FIG. 18A, which is taken along the line 18B--18B in FIG. 18A;FIG. 19A is a plan view of two series-connected photovoltaic elements, each of which is shown in FIGS. 18A and 18B, as seen from their light-receiving surface side.FIG. 19" . . . .