Heat pump hot water systems use a heat exchange system that absorbs the heat from the surrounding air and uses it to heat your water.
Essentially, the system’s heat pump pulls air outside the pump into its evaporator with a fan. The evaporator’s piping contains a special refrigerant, which the warm outside air turns into gas. The refrigerant gas is then pumped through a valve by a compressor. This compression process generates heat, which a heat exchanger then moves from the gas pipes to the water storage tank.
These processes can be powered by the energy generated from solar panels, although regular electricity will work too.