The lithium battery is charged with a variable current during the day by a PV panel and is discharged with a controlled power during the night to light LEDs block. The battery module is positioned directly below the PV panel protected with the circuit board in a hard and sealed casing. During daylight, the PV panel charges the battery with an average current during a day of 100mA. The charge is cut when high voltage cut-off is reached: 3.6V.During the night, LEDs blocks are switched on and the batteries are discharged.