content: Placing the cells on private property opens up an enormous number of issues and would undoubtedly result in an exponentially slower rollout. The whole point of placing them on roads is that they're on public land and countries can begin rapidly transitioning away from fossil fuels. You're vastly underestimating the efficiency of solar cells. Setting up a solar cell is not like setting up, for instance, satellite TV where if a slight cloud cover comes in or if you're pointed a few degrees off then everything falls to pieces.  Solar technology is already productive to the point that even a less than optimal layout can provide enormous levels of power. NASA for instance commissioned a study from MIT to determine what would be the optimal power source for a new Mars colony. They compared a number of alternatives and solar ended up coming out on top in power/volume (critical for the trip over there where there is limited cargo room available), and power/weight compared even to nuclear! And that was obviously accounting as well for inclimate weather on that planet such as major dust storms. For instance one of the benefits of these cells is that they've already been shown to be capable of using some of their energy to melt snow. Not only does this provide a benefit for the cells themselves, it also provides a huge benefit for any roadways made of these cells. Here is an image of the top layer that the company that's testing out similar technology in the US will be using.