because 1 - 1gw of solar capacity isn't the same as nuclear, even 3gw of solar isn't the same as 1gw of nuclear (to get a proper perspective, look at germany's grid yesterday& how much overcapacity of solar/wind they have and how much was actually generated/imported). 2 - vogtle unit 4 was 30% cheaper than unit 3, proving positive learning curve, meaning (in theory, according to https://liftoff.energy.gov/advanced-nuclear/ ) new builds should be significantly cheaper