My knee jerk thought is that you have to work significantly harder to secure land for windmills. They have to be distributed such that you require huge tracts of land and/or to secure rights to install a tower on someone else's property. Each of those towers then need additional transmission lines.

While solar might generate less energy per unit area, it is at least condensed so that you could get away with buying a plot and fully exploit the area. You can add additional (unconnected) plots as cheap land becomes available.

I could also see the advantage that solar has quite limited opex after installation. A fleet of windmills may require significantly more resources to keep operating after years of service.