As dusk descends in Sagar island in the Sunderban delta of West Bengal the unique mangrove system also home to the royal Bengal tiger, life no longer plunges into darkness. In more than half of the 16 villages in Sagar island, inhabited by 150,000 people who make a living from farming and fishing, five solar power plants help activities continue well after sun-set - a boon for an island too far from the mainland to have conventionl power facilities.