Simpa sells solar power systems on financing to households and shops in rural India. Customers make a small initial payment to have the solar PV system installed, then it’s simply pay-as-you-go for the electricity. Simpa mimics the compelling pricing model of pre-paid mobile phones. But there’s an important twist: These small payments for energy service also add up towards the total purchase price and, once fully paid, the customer owns the system, enjoying clean, reliable, electricity for free.