5.1 Solar Energy Harvesting (SEH) System5.2 Composite Solar, Wind (S+W) Energy Sources5.2.1 Wind Energy Harvesting Subsystem5.2.2 SEH Subsystem5.2.2.1 Characterisation of a Solar Panel5.2.2.2 Boost Converter with Constant-Volage-Based Maximum Power Point Tracking (MPPT)5.2.2.3 Performance of SEH Subsystem5.2.3 Hybrid Solar and Wind Energy Harvesting System5.2.4 Experimental Results5.2.4.1 Performance of the Hybrid Energy Harvesting (HEH) System5.2.4.2 Power Conversion Efficiency of the HEH System5.2.5 Summary5.3 Composite Solar, Thermal (S+T) Energy Sources5.3.1 Overview of Indoor Energy Sources5.3.2 Indoor SEH Subsystem5.3.3 Thermal Energy Harvesting Subsystem5.3.4 HEH from Solar and Thermal Energy Sources5.3.4.1 Characteristics of a Solar Panel and Thermal Energy Harvester Connected in Parallel5.3.4.2 Design and Implementation of an Ultralow-Power Management Circuit5.3.5 Experimental Results5.3.5.1 Performance of a Parallel HEH Configuration5.3.5.2 Power Conversion Efficiency of the HEH System5.3.5.3 Performance of the Designed HEH System for an Indoor Wireless Sensor Node5.3.6 Summary