Solar panels do not produce nameplate capacity because of clouds, rain, snow, and nighttime. So, we have to build significantly more 'capacity' (GW) in order to produce the amount of energy we actually consume over time (GWh). Naturally, this is why energy storage is so important.

Your math is wrong in other ways too, because you are assuming that in the future we will be consuming the same amount of electricity as we are consuming today. That's pretty silly, since today we are only beginning to electrify buildings, manufacturing, and transportation. In order to do that, we will need additions of 3,000 GW of capacity each year.