Transporting life-saving medicines in mountain villages and areas with high temperatures will be easier with the invention of 'solar rucksack'. According to Wolfgang Wasserthal who designed the device along with members of the Agrarian Sciences department of Berlin's Technical University, the 6.5 kg invention which resembles a thermos flask contains a panel which can be attached to a rucksack carried on the back of the user. The panel is imprinted with 75 watt solar reflectors. The solar energy is conducted into the housing of the 60 cm device and powers a cold storage unit which keeps the contents in the unit at a constant temperature of zero degrees. The device has been the result of a three-year research .