As you can see from the map below solar insolation variation can be as much as 225 Watts per meter squared from the lowest to highest levels on land in the world. This large disparity means solar power is much more effective in certain areas. It may be that in the future one of our most “useless” biomes, the desert, will be providing the bulk of the world’s energy supply. The black dots on the map below are the amount of land we would need to harness solar energy from to fulfill worldwide energy demand of 18TW.
The reason insolation varies so muich is due to a variety of factors. Look at the image below to see how solar energy gets from space to solid ground and back again. As you can see 174 PW of energy enter the atmosphere. We lose 10 PW immediately due to reflection off the upper atmosphere, another 35 to clouds, and an additional 33 absorbed as heat into the atmosphere. This is a 78 PW or 45% loss before the solar energy has even reached the ground. These factors are why some areas get more solar energy than others.
One futuristic idea for maximizing insolation for solar power is using satellite solar collectors. Being outside the atmosphere means maximum solar exposure resulting in higher levels of electricity generated. Solar energy converted to electricity using photovoltaics could then be beamed down to power stations on Earth using microwave technology. In a geosynchronous orbit these satellites could provide a continuous energy source and at much higher efficiency than similar Earth based solar power plants. Although it sounds like science fiction the technology already exists to make solar power satellites a reality but they are still cost prohibitive at this point.Sponsors: