Actually its not. The TFA makes the same comparison so many do with solar. That is per watt installed. Which is total bullshit. That watt of installed power will only produce 1 watt, for about 30min on just one perfectly fine day in the summer, if its in space. I like to call them brochure watts. Since real installations are probably never ever going to get that claimed watt in any real life conditions.
The average power you get out of 1GW of solar panels is at best 32% of the peak (in practice it is quite a bit lower, like 25%), and only in summer. It is much lower in the winter months, and you will often need to "time shift" all that energy.