Other technologies might have some improvements from miniaturization, but I don't think the principle applies for solar cells. You obviously can't just shrink a cell and keep the same output[1]. What you can do is learn how to shave costs and improve efficiency, and also amortize R&D. Eventually you reach somewhere with very good efficiency and costs close to the raw material cost.
[1] That said, maybe you can shrink the thickness of a cell? That being the case, at one point just the cost of the frame for keeping the cell integrity (specially under wind loads etc.) would start dominating costs, and also the (copper) wiring outputting power from cells. I wonder how far we are from this being the case?
Wind power is interesting because it's mostly a mechanical problem (or at least there's a significant mechanical component). You have to transport the forces on a moving blade, or some kind of moving part (it has to be moving due to P=F.v), so all those parts have a minimum thickness necessary to offload those forces to the ground. It would increase mechanical efficiency (by requiring less load for a given power) if you could increase the velocity of the moving parts, but wind speed itself is limited. You could try funneling the wind, but that introduces structures which themselves suffer stresses (and also induce drag lowering efficiency). There's a limit (at material/W) given by wind speed, and specific strength of the structural material.
This very long exponential improvement (miniaturization) march is a somewhat unique effect to information processing[2], because information can in principle be represented at any scale. That's not to say that all those technologies can't be significantly improved. Generally automation, mass production, along with (limited) efficiency improvements and general cleverness can go a very long way.
[2] I don't mean to be taken as law: there are probably also applications (outside information processing) that you can only do well with the benefit of certain scales. For example, the cells of our bodies are wonderful mechanisms whose magic really works because they can each play tiny mechanisms and deploy molecular-scale objects to act on such tiny scales, and the billions of them make machines that have no parallels in terms of large-scale fabrication (including self-repair, filtration of compounds, ...).