Electricity products as small as solar lanterns or as large as mini-grids connecting many households play a significant role in electricity access across Africa and Asia. These ‘decentralised energy systems’ complement grid extension, but need public and private investment of over US$20 billion annually to meet the ambition of the SDGs. It has taken a decade to reach about US$2 billion worth of investments into private companies. Looking to 2030, IIED has identified aggregation as a promising accelerant to energy access, one that should interest impact investors, institutional financiers, foundations and others. As well as ‘crowding in’ more investment, aggregation can nurture sustainable markets with further support, including technical assistance and quality assurance. Importantly, aggregation can focus resources on those people most at risk of being left behind by established approaches.