The energy efficiency of the Wireless Sensor Network (WSN) deployed in a Smart Grid facility is a key criterion for the performance of a WSN integrated supporting system. Since small form factor sensors used in the Smart Grid have limited battery capacity, the energy saving for sensor nodes is a major design goal for WSN protocols. In the past, our strategy is to install a large number of core nodes with backhaul connections to ensure the reliable connectivity for low power sensor nodes. This strategy leads to a high overall cost for WSN deployment. In this paper, we propose a lightweight mesh networking solution to reduce the WSN core network deployment cost while keeping the same level of energy consumption for sensor nodes. We have developed a prototype system in our lab to demonstrate the feasibility of our proposed mesh solution using BLE chipsets. Comparing with the BLE-Mesh solution, our solution can save 40-70% energy for low power sensors and increase the channel capacity between 100-200% depending on the size of sensor data.