Renewable energy technology is a viable and promising solution toward achieving self-sustainable low power wireless sensor networks. However, the uncertainty and fluctuations in energy availability require a sophisticated energy management scheme, i.e., energy demand of each sensor node at any time does not exceed its available energy. In this paper, we propose to continuously adapt the energy requirements of sensor nodes based on availability of renewable energy sources, network routing needs and application quality constraints - addressing these trade-offs is our distinctive contribution in this paper. We present a novel algorithm to find the optimal uniform data quality for approximated data collection in a multihop energy-harvesting wireless sensor network (EH-WSN). Our approach guarantees routing sustainability in the network and has significantly less failed data queries (<;2%) as compared to a state-of-the-art energy-harvesting-aware routing protocol [10][11] which is not aware of data quality.