If it all comes together, solar will provide 27pc of the world’s power by 2050, with the fastest catch-up in the Middle East, Africa, and Asia. The biggest gains will be in off-grid regions covering 1.3 billion people, which will leapfrog the 20th century model of grid infrastructure just as mobile telephones have swept regions with no fixed lines. The agency said the best zones for capturing solar rays is between latitudes of 15 to 40 degrees on either side of the equator, and best at higher elevations. Tropical regions tend to be cloudier.