In energy-harvesting wireless sensor networks (WSNs), not only energy savings but also efficient energy utilization is required. This study suggests a scheme that indicates when to send data decided by predicting the remaining energy of a node, and aggregates sensed data to increase the amount of data arrived at the sink node. With this method, if the estimated remaining energy of a node is expected to run over the capacity, it transmits aggregated data or else it turns off its radio and only stores sensed data to decrease the blackout time of nodes. Simulation results show that the proposed scheme decreases the blackout time of nodes and increases the data collecting rate efficiently compared to both normal data sending and the specific amount of aggregated data sending cases.