After the popularization of sensor networks, the size of the monitoring region and the number of sensor nodes will grow to an enormous scale. In such large-scale sensor networks, multi-hop communications between sensor nodes will be necessary to cover the whole monitoring region. Moreover, sensor nodes should be grouped into clusters to enhance scalability and robustness. Therefore, we believe that multi-hop communication between clusters is preferable for large-scale sensor networks. To clarify the fundamental characteristics of this form of communication, we analytically derive the network's power consumption and compare it with other routing methods using TDMA communication and an interference-free transmission schedule. The results show multi-hop communication between clusters is preferable in large-scale sensor networks because it can alleviate heavy relaying loads near the sink node and it has a shorter data collection time compared with simple multi-hop communications without clusters. Knowing how much performance degradation arises when interference is unavoidable is essential for multi-hop communications in clustered sensor networks. Therefore, we compare interference-free TDMA communication with CSMA/CA communication which can cause interference in clustered sensor networks. Consequently, we show that although the data collection time is about 3.7 times longer when using CSMA/CA, the power consumption can be suppressed to 12%.