The amount of light (irradiance) radiated to the Earth is measure in kWh/m^2/(day/year). From the National Research Energy Lab (NREL) image(1) below you will see that Germany (1,000-1,500 kWh/m^2/Year) produces the same amount as Alaska, and Germany is producing 50% of their electrical needs from solar. Here in the Inland Empire we produce between 1,700-1,800 kWh/m^2/Year.