Lack of access to modern forms of energy hampers eforts to reduce poverty. The provision of electricity to of-grid communities is therefore a long-standing developmental goal. Yet, many of-grid electrifcation projects neglect mid- and long-term operation and maintenance costs. When this is the case, electricity services are unlikely to be afordable to the communities that are the project’s primary target. Here we show that, compared with diesel-powered electricity generation systems, solar photovoltaic systems are more afordable to no less than 36% of the unelectrifed populations in East Asia, South Asia, and sub-Saharan Africa. We do so by developing geo-referenced estimates of afordability at a high level of resolution (1 km2 ). The analysis illustrates the diferences in afordability that may be found at the subnational level, which underscores that electrifcation investments should be informed by subnational data.