Optimal Power Management with Guaranteed Minimum Energy Utilization for Solar Energy Harvesting Systems

In this work we present the first formal study on optimizing the energy utilization of energy harvesting embedded systems while giving bounds on the minimum energy usage. Furthermore, to deal with the uncertainty inherent to solar energy harvesting we propose to use (i) a finite horizon scheme, and (ii) anon-uniformly scaled energy estimation based on an astronomical model. Under certain realistic assumptions, the finite horizon scheme can provide guarantees on minimum energy utilization, and therefore minimum utility. We show that a single non-uniform scaling function is applicable to solar energy traces from diverse locations. We further propose and evaluate a piece-wise linear approximation for efficient implementation as a small look-up table for resource constrained embedded systems. With extensive experimental evaluation for eight publicly available datasets and two datasets collected with our own deployments, we quantitatively establish that the proposed solution is highly effective at providing a guaranteed minimum utilization, and significantly out-performs four previously proposed solutions.