Heat Pump Hot Water Systems will heat water using Solar Energy (without the need for Solar Panels) by extracting ambient heat from the environment and using this to heat the water.
But how specifically does a Heat Pump work?
Refrigerant runs through a fan coil (the evaporator) and because the refrigerant is colder than the surrounding air, it collects heat energy from it. This Heat Energy then vaporises the refrigerant, turning it into a Gas. This vapour (gas) is then compressed, resulting in an increase in pressure and temperature. This high temperature vapour (gas) is then passed through coils of copper tube immersed in the water heater tank and as it condenses back into its liquid form, it gives off its heat to the stored water.
Essentially, they operate like a Fridge in reverse, whereby a refrigerant is heated up and turned into gas. This is then compressed into a liquid, resulting in the release of Heat Energy.