热泵热水器，又被称为“空气能热水器”，就是利用逆卡诺原理，通过介质，把热量从低温物体传递到高温的水里的设备。热泵装置，可以使介质（冷媒）相变，变成比低温热源更低，从而自发吸收低温热源热量；回到压缩机后的介质，又被压缩成高温（比高温的水还高）高压气体，从而自发放热到高温热源；实现从将低温热源“搬运”热量到高温热源。热泵工作的原理与空调完全一样。避免了传统太阳能产品在阴雨天气、夜晚不能工作的缺陷，外界温度在5-25℃时，能效比高达300-500%。
Heat pump water heater, also known as "air energy water heater", is a device that uses the inverse Carnot principle to transfer heat from low-temperature objects to high-temperature water through medium. The heat pump device can make the medium (refrigerant) phase change into a lower heat source than the low-temperature heat source, so as to spontaneously absorb the heat of the low-temperature heat source; the medium after returning to the compressor is compressed into a high-temperature (higher than the high-temperature water) high-pressure gas, so as to automatically release the heat to the high-temperature heat source; realize the "transfer" of heat from the low-temperature heat source to the high-temperature heat source. The working principle of heat pump is exactly the same as that of air conditioner. It avoids the defect that the traditional solar products can not work in rainy days and at night. When the external temperature is 5-25 ℃, the energy efficiency ratio is as high as 300-500%.