responds to the signal by switching on the light 5 it must be noted that the light source 5 can be of any type provided that it generates luminous energy that will be converted into electric power by the solar cell 7 for instance the light 5 could be a lamp a light bulb a tungsten halogen lamp etc fig2 shows another example of architecture for implementing the invention the device 1 solar cell 7 battery 4 switch 2 and light 5 are similar to the ones of fig1 however the system of fig2 comprises a coordination device 8 which coordinates the exchanges between the device 1 and the switch 2 possibly as well as other nodes of a network if any this architecture is well adapted to the networked applications where a plurality of sensors actors may communicate with each other in order to achieve predefined tasks upon detection that the remaining load in the battery 4 is less than the first threshold the device 1 sends a signal to the coordination device 8 reference 3 a the coordination device 8 interprets the received signal and sends a command signal to the switch 2 so that the light 5 is switched on the command signal sent to the switch 2 by the coordination device 8 can possibly incorporate the initial signal sent by the device 1 for instance this mode of operation implies that both the device 1 and the switch 2 are arranged for communicating with the coordination device 8 such communication can use wireless means such as radio means operating in accordance with the above mentioned zigbee specification 053474r06 for instance therefore the device 1 can operate as long as the associated battery 4 stores enough electric power when the electric power stored in.