Suppose 10 million new solar panels will be installed in some country this year, and there are two options:
A: the solar panels go onto the roofs of 1 million individual houses
B: the solar panels go into 1 thousand large solar farms
With option A, there is a great deal of expense dispatching workers to all the houses, doing all the electrical hookups at each house, advertising to the individual buyers, etc. Then many of the panels will be installed at sub-optimal angles, be partially blocked by trees, go in cloudy locations, etc.
With option B, it is presumably much cheaper and faster to install and maintain the solar panels. It does require some extra land; does option A have any other economic advantages besides that? (Of course, there may be advantages such as people signalling their support of solar power by displaying the panels, but I'd like to focus on direct economic advantages.)