Usually wireless devices require autonomous power supply. They are equipped with radio frequency transceiver modules with relatively high energy consumption especially in data transmission mode. This also means that autonomous power supply of wireless device requires relatively large energy storage. Rechargeable battery in this case is a good solution, but the charging process of a battery takes a long time. In this paper the use of supercapacitor as energy storage for autonomous power supply of wireless node is further elaborated on the example of light sensor for illumination measurement test bench.