I came to admit I can't imagine how the small solar power "field" shown on top of the balloon could possible push that shape through the air - either at a reasonable speed for transport or to counteract wind. If lift isn't a problem as you pointed out above, what might work is a tethered version that basically replaced the need for a tower crane. You could develop a tethered, active mooring that was much like the four-point active anchor system the navy uses to accurately maintain position during submarine rescue.
