Heat Pipe Technology has been in use in Europe and is more efficient in areas where diffuse radiations are more as compared to direct radiations climates. The selective coating on the copper absorber absorbs the heat energy from solar radiation. The liquid in copper tubes gets heated. the liquid rises in the tube and gives energy to the manifold. Thus heating the water in the tank.
Heat Pipe Technology is best for industrial use for temp. application up to 90 C and for Air conditioning application.