There is no way of making a small nuclear power plant - it's got to be big. Which means that the present centralized power systems will become even more so. The power lines and the power plants - and, of course, the users. Now, in the case of nuclear power, there is a very large economy of scale, because of the large cost of controls. So the introduction of nuclear power fits the present centralized power system, and in fact would make it even more centralized.
Solar electricity has to be decentralized.
You produce the electricity on the roof of the building that is going to use it. What that means is that you have to transform the present, centralized power system into a decentralized one. The wires would be used largely as a way of shifting electricity from one place to another, and most of the electricity would be produced locally where it is needed and if you produced more than you need you might shift it through the wires somewhere else. If you have an industry, let's say a factory, that has a certain requirement for electricity, you put in enough photovoltaic cells to take care of that factory. Of course, this cannot be done in every case.