Every night, something unusual happens in Samuel Kimani’s home on the outskirts of Nairobi, Kenya. Samuel, 48, lives with his wife Mary and their three children. Their family supports itself day-to-day through their main source of income, their cow Baraka, whose milk is collected daily and sold directly to customers for about $1.80 a day. Their township has few amenities and grid electricity is available only to the few who can afford it. But at Samuel’s house, two bright lights shine all through the evening.

Samuel used to light his home with a single kerosene lamp, which filled the rooms with smoke and poor-quality light and cost $3 a week. With his low income, Samuel could support his family, but he