Heat pumps (HPs) with the help of electricity use a renewable energy source to supply heat for homes or industrial buildings and to heat tap water. HP is a heating unit that will provide us with heat for our home for some 20 to 30 years to come and has a potential to replace traditional heating systems powered by gas, oil or coal. At this time, there is no other heating system that supplies clean heat with the help of up to 80 per cent of the renewable solar energy during all year.