Vertical Ground Source Heat Pump
It uses solar energy stored in the ground for heating and hot water production. An installation can be made on a very small area, in different locations. Such heat pumps can be operated exceptionally efficiently all year long through employing the constantly high temperature level of the ground (approx. 10 °C) and they can be scaled up to commercial and industrial applications (which is easier than for air-air heat pumps). COP = 4