How much area would be required to power the world (with solar panels alone)

I came across this particular pic which really made me think. I don’t know if they did the math right, but if they did, with a surface as big as the plastic island floating around in the Pacific covered with solar panels, the whole world could be powered. If we consider other sources of clean energy (hydro plants for example), I’m guessing the surface would go down to half. This is do-able. Probably not by 2030, but then again, why not? This type of technology is developing all the time, and it could be complemented by other methods (wind farms, etc), so the required surface could really go down, and this could also be an economic solution. Or maybe I’m just delusional. I honestly don’t know.

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