Abstract The present study aims to address the sustainability of power resources and environmental conditions for heterogeneous cellular networks. To this end, this study examined an autonomous solar power system to supply heterogeneous cellular networks with their required energy sources. Optimal criteria, system architecture, energy production, and cost analysis are discussed based on the characteristics of solar radiation exposure in South Korea. However, the analysis can be generalized to other cases with a slight difference in daily peak solar hours per case. Additionally, this study compares the feasibility of using an autonomous solar power system to feed heterogeneous cellular networks versus a conventional energy source—i.e., the public electric grid. This study shows that the deployment of the solar power system can satisfactorily meet the energy needs of the base stations (BSs) in heterogeneous cellular networks cost effectively, efficiently, sustainably, and reliably and can improve planning by providing cleaner energy.