How Mirrors Could Solve our Energy Problem

Here how much space they have used minimum 2km^2 in my opinion that's a lot of area and what if sun is not shining. Solar panels have lead inside them so after 20-25 which is their life expectancy where they're going to dump it.
It is highly unsustainable an avg thorium nuclear power can be constructed within 0.5 km^2 area.
Nuclear is the only way to go as it is cheap, highly efficient, zero emissions, no waste like uranium.