A solar-powered device (SPD) relay node is coupled to a remotely-located “leaf” node in order to provide the leaf node with network access. The SPD relay node routes network traffic to and from the leaf node via one or more different paths that traverse other SPD relay nodes that reside upstream of the SPD relay node. The SPD relay node determines a specific path across which to route the network traffic based on several different factors associated with the upstream SPD relay nodes, including battery level, solar generation rate, and link quality. The SPD relay node generates a routing metric for each upstream SPD relay node based on these different factors and then routes traffic across the upstream SPD relay nodes based on the routing metric and based on a priority level associated with the network traffic.