Driven by the need to improve energy efficiency and reduce environmental impact, we observe a thrust towards enabling a Smart Grid. It is envisaged that to achieve these goals, the Smart Grid will be equipped with communications infrastructure and mechanisms which will enable near real time control of the grid components. One of the key elements of the Smart Grid is the Automated Metering Infrastructure (AMI) which is expected to facilitate the transport of meter readings from a smart electricity meter at the customer premises to the utility provider, and control data in the other direction. These communications can be realised by deploying a self-organising mesh network composed of smart metering nodes connected to concentrator nodes which in turn are connected to the utility provider data management systems. This paper explores a cooperative communications approach to improve reliability of such mesh networks. The proposed opportunistic forwarding protocol called 'ORPL' has been realised as an enhancement on top of the Routing Protocol for Low Power and Lossy Networks (RPL), a connectivity enabling mechanism in AMI mesh networks. In ORPL, smart meter nodes select multiple candidate relays to facilitate reliable transport of smart metering data to the concentrator node. Moreover, it is designed to work in a distributed manner thereby ensuring scalability.