Design considerations for solar energy harvesting wireless embedded systems

Abstract

Abstract-Sustainable operation of battery powered wireless embedded systems (such as sensor nodes) is a key challenge, and considerable research effort has been devoted to energy optimization of such systems. Environmental energy harvesting, in particular solar based, has emerged as a viable technique to supplement battery supplies. However, designing an efficient solar harvesting system to realize the potential benefits of energy harvesting requires an in-depth understanding of several factors. For example, solar energy supply is highly time varying and may not always be sufficient to power the embedded system. Harvesting components, such as solar panels, and energy storage elements, such as batteries or ultracapacitors, have different voltage-current characteristics, which must be matched to each other as well as the energy requirements of the system to maximize harvesting efficiency. Further, battery nonidealities, such as self-discharge and round trip efficiency, directly affect energy usage and storage decisions. The ability of the system to modulate its power consumption by selectively deactivating its sub-components also impacts the overall power management architecture. This paper describes key issues and tradeoffs which arise in the design of solar energy harvesting, wireless embedded systems and presents the design, implementation, and performance evaluation of Heliomote, our prototype that addresses several of these issues. Experimental results demonstrate that Heliomote, which behaves as a plug-in to the Berkeley/Crossbow motes and autonomously manages energy harvesting and storage, enables near-perpetual, harvesting aware operation of the sensor node.

Rechargeable sensor activation under temporally correlated events

“…[4] considers a restrictive sensor energy model, wherein a sensor node could be activated only upon complete recharge of its battery, and shows that a simple threshold based node activation policy achieves performance more than 3 4 times the maximum achievable performance. Here the spatial correlation is modeled by introducing correlation in the discharge and recharge intervals of the various sensors, and the performance bound of 3 4 is shown to hold both in the presence as well as absence of spatial correlation.…”

“…[4] considers a restrictive sensor energy model, wherein a sensor node could be activated only upon complete recharge of its battery, and shows that a simple threshold based node activation policy achieves performance more than 3 4 times the maximum achievable performance. Here the spatial correlation is modeled by introducing correlation in the discharge and recharge intervals of the various sensors, and the performance bound of 3 4 is shown to hold both in the presence as well as absence of spatial correlation. [5], [6] consider sensor systems where a sensor could be activated even if it is N. Jaggi and K. Kar recharged only partially, and show that a threshold based node activation policy achieves asymptotically optimal performance with respect to the sensor energy bucket size, under various spatial correlation based sensor system models.…”

Towards Autonomous Energy-Wise RObjects

“…The small robot Alice has been powered using only thin film amorphous silicon cells and a 3000 lumens projector, with an achieved power density of 27.8 W m −2 [4]. Finally, wireless sensor nodes can use efficiently the power of small solar cells [11,27].…”

A Self-powered Module with Localization and Tracking System for Paintball

“…The next three wireless sensor platforms with energy scavenging technology, namely Heliomote [3], Prometheus [4] and Trio [5], contain off-the-shelf modules Mica2 [9] for the first one, and Telos [7] for Prometheus and Trio. In contrast to VIBES, Heliomote has solely NiMH rechargeable batteries as energy buffer.…”

“…However, the availability of heterogeneous WSN platforms has resulted in a problem of inflexibility: it is difficult to exploit a wireless sensor node and a harvesting component together. Basically, WSN platforms are being developed for particular cases [3,5] or have already been integrated with a harvesting component [2].…”