A drilldown on Micro-Solar Energy Harvesting
Friday, August 8th, 2008Today’s typical sensor nodes run on batteries, thus have a limited lifetime. Solar energy harvesting is an interesting complement or alternative. There are several systems built with unique set of requirements. However, not much has been done to formalize application driven constrains, model and systematize micro-solar design of energy subsystems.
We just stumbled over some neat research from Jaein Jeong et al, from UC Berkeley, that shed some light on this topic.
The authors develop a taxonomy of the micro-solar design space identifying key components, design choices, interactions, challenges, and trade-offs. Based on the analysis of two different systems (Heliomote and Trio) they propose design guidelines for future micro-solar powered systems (see paper, talk).
Furthermore, they present a systematic approach that composes models of the relevant pieces to appropriately select and size the components. The approach is demonstrated through the design of the HydroWatch weather node, micro-solar subsystem and network, in the context of a microclimate monitoring project in a deep forest setting (paper, talk).
Interestingly, they have found the speckled nature of the illumination in the forest environment dramatically affects the solar current in the panel which wouldn’t be improved by its larger size, but instead, by the arrangement of more and smaller cells connected in parallel. Also, the useful range of voltages from these panels is very limited and therefore proper coupling of the electronics to profit on these constrains is as relevant as other optimizations.
Enjoy your readings.
