That's the key number this article should have found out and quoted. They should have compared it to grow-lamps and other closed-environment food production methods. If the numbers didn't look good, they should have also quoted an engineer saying "this is what we can do now, but we hope to get it down to X, and it theoretically can go as low as Y".

Those numbers could have been brought into context by saying "with current solar technology, that means the whole world population could be fed with solar panels the size of Ethiopia".

https://factorio.com/