Nairobi-based off-grid solar firm Sun King has obtained a $5 million Series D equity investment from Acumen to support its entry into the Zambian market.
The funding was delivered through Acumen’s Hardest-to-Reach (H2R) Catalyze programme and placed directly into Sun King’s Zambian subsidiary, representing Acumen’s first country-level equity stake in the company.
Sandra Halilovic, head of H2R Catalyze at Acumen, said the investment will speed Sun King’s scaling in Zambia, close the energy-access gap and help attract local-currency debt from Zambian financial institutions.
Acumen’s H2R initiative has mobilised nearly $250 million across 17 sub-Saharan countries, with $60 million available for equity, debt, grants and technical assistance.
The new equity is intended to act as growth capital and a catalyst for larger local-currency financing, complementing Sun King’s model of using instalment-based payments to fund solar home systems.
In Kenya, Sun King completed a $156 million local-currency securitisation in 2025, backed by Kenyan banks and development finance institutions, to package future customer repayments into tradable assets.
Acumen estimates the Zambian rollout could reach almost 5.6 million people over the next five years, with up to 4.5 million gaining electricity for the first time.
The expansion aligns with Zambia’s Presidential Solar Initiative, which targets the addition of 1,000 MW of solar capacity to the national grid, while Sun King focuses on households and businesses not served by the grid through its pay-as-you-go scheme.
Founded in 2007, Sun King now operates in 11 African and Asian markets and previously raised $40 million from Lightrock in December 2025 and $260 million in a 2022 Series D round led by BeyondNetZero.
To date the company reports having secured $547 million across 20 funding rounds, issued $1.3 billion in solar loans and served nearly 10 million customers across Africa.
