All the fresnel lenses i've seen have the focus in the center of the panel, because they only expect you to use one at a time. I would imagine it wouldn't be t

All the fresnel lenses i've seen have the focus in the center of the panel, because they only expect you to use one at a time. I would imagine it wouldn't be too hard to make an array of n^2 (9?) fresnel lenses where they each have the appropriate pattern for their position in the array. I think you might be able to get away with three molds for a 9-array (middle, side, corner). The resulting lenses would be much cheaper to manufacture and ship because shipping a stack of 9 6-ft squares is much easier logistically than shipping an 18ft square.