The Effect of Flat Panel Reflectors on Photovoltaic Energy Harvesting in Wireless Sensor Nodes Under Low Illumination Levels

This paper discusses the application of flat panel reflectors in conjunction with photovoltaic cell used to power wireless sensor node. The aim of the reflectors is to increase the indoor ambient light energy harvesting efficiency, especially under low illumination levels (<;200 lx). The benefit of the reflectors usage is in the reduction of the node cold boot time and increase of the data transmission frequency. In addition, the physical placement and orientation of nodes in a wireless sensor network is less dependent on the illumination conditions. This paper presents a simple theoretical model suitable for the calculation of the optimal inclination angle for the reflectors. Experimental data show that the cold boot time can be reduced up to 30% and data transmission frequency increased almost twice by using two reflectors of the same size as the photovoltaic cell. The reflectors are produced in the conventional printed circuit board technology, so they can be incorporated into the node design with negligible costs.