When Tanzanian company ARTI Energy brought solar lights to Kiromo village in the eastern district of Bagamoyo eight years ago, local people were excited but found them expensive. “I really liked those lamps, but I could not imagine then that I would ever own one,” recalled Kiromo resident Salum Ali. The company realised the upfront investment needed to buy modern lighting devices was beyond the means of the average rural Tanzanian. Guided by the belief…