African Infrastructure Investment Managers (AIIM) has invested US$31 million for a 28 percent stake in the East Africa operations of U.K.-based, Africa-focused off-grid energy solutions provider BBOXX. The company sells solar systems, billing users on a pay-as-you-go basis, and will partner with AIIM to accelerate the rollout of its products in the region. AIIM invested through African Infrastructure Investment Fund 3.