Does that account as well for the longevity of it? The current nuclear reactors lasted around 40 years already without much issues, I wouldn't bet the solar installations to last that long.
Almost no one cares if your desktop computer can last 40 years. And PV is improving so fast that making it last 40 years would be nearly as pointless.
And nuclear does not improve in a "slow paced", I don't know where you got that impression, there's been a lot of innovations on the last 10 years.
£100+ billion in 2013 https://www.theguardian.com/environment/2013/jun/23/britain-...
£161 billion in 2017 https://web.archive.org/web/20170516093449/https://www.gov.u...
£234 billion in 2018 https://www.gov.uk/government/publications/nuclear-provision...
... and counting.