Hybrid Solar-Wind Energy Harvesting for Embedded Applications: Supercapacitor-Based System Architectures and Design Tradeoffs
To enable off-grid deployments of autonomous systems for extended operational durations, robust energy harvesting in the medium power range (1-10 W) is essential. Supercapacitor-based solar energy harvesters have emerged as a popular alternative due to their long lifetime under repeated charge-discharge cycles, low maintenance, environmental friendliness, and energy predictability and scalability. Despite their advantages, such systems are not well matched with applications that require power continuously over their operational lifetime because solar power is unavailable during nights and severely reduced on cloudy days. For such applications, it is beneficial to combine solar power with another power source-such as wind-that exhibits complementary availability. In this paper, we present multiple solar/wind (hybrid) supercapacitor-based harvesters, leveraging existing open-source solar-only harvester designs. Our designs center around three main categories that i) add wind harvesting capability to create a wind-only harvesting system, ii) use multiple harvesters for utilizing hybrid sources of power and for providing fault tolerance, or iii) use a single harvester in a time multiplexed configuration to simultaneously harvest from multiple power sources. We provide extensive experimental results to document the functionality and operational performance of a representative set of these designs.