Solar Irradiation = 1365MegaWatt/km² =91 MegaWatt per human on earth today ...

Taken into account that 71% of earth is ocean water, there is a lot of sun shining into the ocean water.

But 100%-71%=29% of 91MegaWatt is still 26MegaWatt solar radiation per human on continental land shining on the average 12 hours out of 24 leaving us with 13MegaWattHour per day per human and if we cover all continental land with solar panels with 20% power-efficiency then we get 2,6MegaWattHour per day per human.

An average family in modern society would need less than 5kiloWattHour per day so 2,6MegaWattHour per day would serve 5 thousand families in a modern society.

So to serve all electricity needs for all people world wide, we need to cover per km² about 100m² with solar panels ?

Or did I make a mistake in the arithmetic ?