Nairobi-based off-grid solar company Sun King has secured a $5 million Series D equity investment from Acumen, a global impact investor. The investment, made through Acumen's Hardest-to-Reach (H2R) Catalyze initiative, will be used to expand Sun King's operations in Zambia. This marks Acumen's first country-level equity investment in Sun King. The funding will support the company's pay-as-you-go solar business in Zambia.
The investment will enable Sun King to scale its operations in Zambia and attract funding from local financial institutions. According to Sandra Halilovic, head of H2R Catalyze at Acumen, the investment will help close the energy access gap in Zambia. Acumen's H2R initiative has raised nearly $250 million to expand access to off-grid solar across 17 sub-Saharan African countries. The initiative has $60 million available for equity, debt, grants, and technical assistance.
Sun King's expansion into Zambia is part of its strategy to replicate a financing model used in other African markets. The company completed a $156 million local-currency securitisation in Kenya in 2025, backed by Kenyan banks and international development finance institutions. This financing model allows Sun King to package future customer repayments into financial assets that can be funded by banks and other investors.
Zambia offers a large off-grid market, with limited electricity access, particularly in rural areas. Acumen estimates that its support could enable Sun King to reach nearly 5.6 million people in Zambia over the next five years. As many as 4.5 million people could gain access to electricity for the first time. The expansion aligns with Zambia's broader push to increase solar power generation.
The Zambian government has targeted the addition of 1,000MW of solar capacity to the national grid through its Presidential Solar Initiative. Sun King's business addresses a different part of the market, providing distributed solar systems to households and businesses that are not connected to reliable grid electricity. The company uses a pay-as-you-go model that allows customers to acquire solar home systems and repay the cost through smaller, recurring payments.
Sun King was founded in 2007 and operates across 11 African and Asian markets. The company raised $40 million in equity from Lightrock in December 2025 to support the expansion of its decentralised energy business. In 2022, Sun King raised $260 million in a Series D round led by BeyondNetZero, the climate investing platform of General Atlantic.
Sun King has raised $547 million across 20 funding rounds, including nine debt rounds, and has issued $1.3 billion in solar loans to nearly 10 million customers across Africa. The company's expansion into Zambia will depend on its ability to build a distribution network, acquire and retain customers, and secure sufficient local financing to support its PAYG model.
Key points
- Sun King secures $5 million from Acumen to expand off-grid solar operations in Zambia.
- The investment aims to help Sun King scale its pay-as-you-go solar business and attract local-currency debt.
- The expansion could enable Sun King to reach nearly 5.6 million people in Zambia over the next five years.
