Improved fuel cell secondary interconnect

A fuel cell system comprises (i) a plurality of stacked tubular substrates 1030, each with a plurality of series-connected fuel cells (340, fig 3; 640, fig 6) on at least a first major surface, and first and second sheet conductors 1034 providing an electrical path between major surfaces of the tubular substrates, located proximate each end of the substrates, and (ii) a secondary interconnect 1066 providing an electrical path between the tubular substrates via the first electrical conductors, possibly via a secondary interconnect layer 1058. The substrate has a pair of opposing major surfaces, which are preferably planar and parallel each other, with a plurality of parallel channels between the major surfaces extending between first and second ends of substrates. The fuel cells are preferably solid oxide fuel cells. A plurality of series-connected fuel cells may also be located on each of the second major surfaces. The sheet conductors may comprise a conductive ink trace. The secondary interconnect may comprise a corrugated resilient member positioned between adjacent fuel cell tubes (as shown), wires, a ceramic wedge (960, fig 9A) or shim (962, fig 9B) or a resilient members (964, figs 9C-D) which is frictionally fit over the first sheet conductors.