Solar Inexhaustible Power Source for Wireless Sensor Node

Currently the appearance of really low power wireless transceivers is motivating the use of renewable energies to power embedded wireless sensor nodes in many applications. Nevertheless, energy storage and its degradation still keep on being the main issues in the design of any battery powered device. We present an autonomous power source based on a new system architecture, which uses the energy scavenging to replenish two different rechargeable energy buffers instead of the conventional single one. Combining appropriately a degradable large backup battery (Lithium-Ion) and a shorter but non degradable storage element (Supercapacitor), the lifetime of the group can be widely extended to what we can call near perpetual operation, for such a changing technology. This paper analyses and describes the keys of the design and the optimal hardware selection to implement an inexhaustible power source. Finally we implement a real one that takes advantage of the sunlight energy and intelligently manages both energy buffers, without the human intervention and without depending on any programmable device like microcontrollers.