Abstract: The subject disclosure provides for harvesting energy and converting the harvested energy with high efficiency for multiple power rails to a system load. For example, harvested energy is converted to a regulated output for a first power rail when the harvested energy satisfies a maximum power point tracking (MPPT) threshold, where the MPPT threshold corresponds to a high conversion efficiency. When the harvested energy drops below the MPPT threshold, the regulated output can be driven with stored energy associated with a second power rail from a super capacitor charged with the harvested energy during a high efficiency phase. This helps maintain the high conversion efficiency at the regulated output. In the event that the super capacitor does not have sufficient stored energy, a backup battery may drive the regulated output associated with a third power rail while still maintaining the high conversion efficiency at the regulated output.