Despite recent improvements to electricity access in lower-income countries, reliability remains low for many. Local renewable energy infrastructure supplementing the national grid offers a promising route to improved reliability for rural communities. However, improvements in the reliability of national grids create risks for investors including the possibility of “stranded” renewable assets. We use energy-system modelling to explore ways in which solar PV-based mini-grids could be interconnected with national grids. We explore the impact of reduced demand to quantify the investment risks of losing customers. Our results indicate that national grid-connected mini-grids can reduce the unit electricity costs for communities whilst also increasing reliability and reducing the carbon intensity of electricity in line with SDG 7 goals. Reductions in demand have a minimal impact at lower levels but at moderate levels are likely to undermine economic viability. Finally, we discuss policy interventions to facilitate and protect investing in national grid-connected mini-grids.