"Solar power potential in countries around and near to Europe. The “economic potential” is the power that could be generated in suitable places where the direct normal irradiance is more than 2000 kWh/m2/y.
The “coastal potential” is the power that could be generated within 20 m (vertical) of sea level; such power is especially promising because of the potential combination with desalination.
For comparison, the total power required to give 125 kWh per day to 1 billion people is 46 000 TWh/y (5 200 GW). 6000 TWh/y (650 GW) is 16 kWh per day per person for 1 billion people."
(de MacKay 2008)