It is not that simple. If the market was left to sort it out then solar and wind would rarely be used where there is a grid because because they are not baseload or disapatchable which makes them implicitly less useful than other power sources.
True, wind/solar power is not dispatchable and solar panels can't handle baseload. However, there are a couple of things to keep in mind:
- One advantage to solar panels is that its peak production happens to coincide with times of higher energy demand. It can't provide energy at night (not without some sort of storage mechanism), but demand will be lower at night anyways. So, use Nuclear/wind/hydro/etc. for the base load, and solar for the 'extra' energy requirements n the day
- There are some solar technologies that may actually be able to provide baseline power generation. Solar thermal energy (using molten salts for thermal energy storage) could be used instead of solar panels
- One of the plans for wind is to have wind farms in multiple areas of the country, so that even if the wind is not blowing in one area, other wind farms on the grid can make up for it.
I have spent a lot of effort here to promote nuclear, and I do think nuclear should be given a higher priority by governments than it is. But, I'm not necessarily opposed to the use of renewables; I just think that there are a lot of problems and that optimism regarding wind/solar should be tempered. But if they can be added to the energy mix, then great.