The current US plants are all getting extensions to 80 years of operation, and experts see no problems with going to 100.
How many times do you have to fully replace the panels in that timeframe?
How many times the batteries?
And what about seasonal storage?
3 times, assuming current panel lifetimes. The panels will be even cheaper by then and will likely be robotically installed.
> How many times the batteries?
Maybe 4 times? Same as the panels; they'll be cheaper and easier to replace.
Maintaining and upgrading nuclear plants also has a cost. They don't last 100 years for free.
> And what about seasonal storage?
Might be unnecessary with enough overbuilding and grid interconnections. Or there might be cheaper storage technologies. Or batteries might become cheap enough that fewer duty cycles for season storage become economical.
You don't have to replace them. After 30 years the panels will still be producing >80% of their initial output.
Of course it might be economical to replace them with newer panels, since solar tech is getting better every year. 30 years ago solar cost roughly $8/W of peak capacity (adjusted for inflation), and today were somewhere around $0.1 to $0.3 per watt. Assuming $0.25, that's a 32x increase.
Imagine in 30 years we replace them with solar panels 32x as cost-effective as today's (and same for batteries, whatever the factor might be). How competitive does the nuclear plant look?