These images from NASA show the average solar insolation, or rate of incoming sunlight at the Earth’s surface, over the entire globe for the months of January and April. Such images are particularly useful to engineers and entrepreneurs who develop new technologies for converting solar energy into electricity. To attain best results, most devices for harvesting sunlight require an insolation of greater than 3 to 4 kilowatt hours per square meter per day.
NASA’s Surface Meteorology and Solar Energy website contains global solar energy data for 1195 ground sites, including Greensboro and Raleigh NC. You can also retrieve meteorological and solar energy data for your location -choosing from a variety of parameters.