NASA is considering the use of a nuclear plant to power their lunar outpost. The main benefit that nuclear has over solar is the ability to generate power during the long lunar night (~14 days). Unless based in orbit, solar power would require the outpost to be designed with both:
- enough extra generating capacity to provide power during the two week long night
- massive, bulky batteries to store energy during the night
The length of day can addressed by siting the outpost near the poles but there is are trade offs to doing that. The terrain is much, much rougher in the terrae (highlands) that covers the poles. Placing an outpost near the poles limits the terrain easily available for exploration. The poles are covered almost exclusively by lunar terrae. The maria are located on the near side in the lower latitudes. The maria has the mineral that most easily provides oxygen: ilmenite. It also contains the highest concentration of KREEP, a source of potassium and phosphorus. But building an outpost near a polar mountain that has access to nearly continuous light also has benefits. High mountains give larger larger line of sight communication range, which is important because there is no lunar ionosphere to bounce radio waves. There are craters that are likely to be permanently shaded, from which we can postulate the very rare and necessary volatile might be found because they wouldn't have evaporated.
If there is manufacturing base established on the Moon, the solar option might be the easiest to implement. Thorium based nuclear power can be done using lunar materials, but it is orders of magnitude more complicated.
The most likely possibility is the there is no manufacturing capability on site, so everything has to be lifted directly from Earth, which is a Very Bad Thing in terms of cost. Silicon solar panels have none of the political stigma that a uranium nuclear power plant has in the case of a catastrophic explosion. Solar panels are also much lighter. Add in the fact that NASA's outpost is likely going to placed near the poles and solar seems to be the best short term option for the lunar base. NASA may be showing some long term strategic planning in its desire to explore the nuclear option. Good news all around.