Efficient solar energy harvester for wireless sensor nodes

An efficient solar energy harvester for low power wireless sensor node is proposed in this paper. In the proposed harvester, maximum power point tracking (MPPT) is achieved by using constant voltage tracking principle. The implementation of the MPPT control circuit is carried out using analog discrete components. This is to minimize the energy consumption in the electronic circuits. Experimental test results obtained from a Polycrystalline solar panel of 45 mm × 76 mm in the laboratory environment shows an average power harvesting of 400 mW under 1 sun solar insolation. The proposed harvester is used to power a battery which subsequently feeds a sensor node. The harvester system provides an overall efficiency of around 93%. The efficiency calculation takes care of power losses in the power management circuit. The solar energy harvester is also tested with a crossbow wireless sensor node (WSN) to monitor temperature in the actual outdoor field environment. The harvester is able to extend the lifetime of the wireless sensor node to almost indefinite period whereas the battery powered WSN becomes inactive after 150 hours of operation.