So You Want to Combine Solar Energy with Air Source Heat Pump?

Air source heat pump is the safest, most reliable & energy-saving hot water system, while solar water heating is a traditional way with such advantages as eco-friendliness and low cost. Air source heat pump water heaters make full use of air energy. In a broad sense, it is also a form of solar energy utilization. The air source hot water heat pump has the following advantages:

• Hot water supply is of low cost, energy storage and energy saving;

• Safe and reliable with a long service life;

• Meet the requirements of environmental protection and emission reduction;

• Compared with water source heat pump, it has the advantages of easier installation with less land occupation, flexible use and thus low initial investment.

Solar hot water supply is the most traditional and economical way in the new energy field. The energy that the sun radiates to the earth, in a sense, is inexhaustible. However, due to the great influence of climate conditions and sunshine changes on the operations of solar collectors, solar collectors can not work effectively on rainy, snowy or cloudy days. In a day, it can only collect heat in the day between sunrise and sunset, so heat collection can not be applied at night. The combination of solar energy and heat pump is a new trend in the development of heat source equipment of central hot water projects in recent years, which can not only achieve energy saving and emission reduction, but can also ensure continuous heating throughout the year. There are two modes to consider for the integration of solar energy and heat pump.

One is that solar panels are allowed to be placed in the building, and there is enough area so that solar energy is applied as the main heat source while the heat pump heating is regarded as the auxiliary heat source. For example, on cloudy or rainy days, the solar water heating system only relies on direct electric heating. However, with the backup of air source heat pump, the solar + air source hot water system can save 60%-75% of the power consumption; when the heat storage at night is insufficient, the heat pump can be turned on to supplement energy.

The second mode is mainly based on heat pump heating while supplemented by solar energy. In order to make the air source heat pump operate efficiently, stably and reliably in the low temperature environment, solar energy is used as its auxiliary heat source (boosting effect), directly heating the water or preheating the water in the water tank. The hot water heating system combining solar energy with heat pump can save energy by 85% (80% of the total load is directly heated by solar energy, and 20% - 40% is borne by the heat pump. In this part of heat load, if the COP of the heat pump is 3, the annual power consumption by heat pump is actually 7% - 14%). Of course, in the heating system with solar energy and heat pump, the type of heat pump can be air source, water source, or ground source heat pump.

So, is the combination of solar energy and air source heat pump the best solution? It can be predicted that, regardless of the initial investment, the energy consumption will definitely be less than that of the heat source equipment with electric heating, fuel oil or gas, and also less than that with air source heat pump water heater only. But if we consider that solar energy and heat pump are two sets of equipment after all, the one-time initial investment is definitely higher, which is more than that of a heat pump unit alone. If the excess investment can be quickly compensated in the annual operation cost savings (for example, within three years), it can be considered that the average life cost of the project is expected to be reduced to a reasonable level.

The combination of solar energy and air source heat pump can overcome the disadvantages in the hot water project by using solar energy or air source energy alone. It can guarantee all year hot water supply, and the energy saving effect is obvious, together with excellent environmental protection and emission reduction. If meeting the limitation of placing solar panels on the roof of the building, the project can adopt heat pump as the main part and solar energy is the driving force. That is, when the solar energy is not enough to heat the water to 55℃, warm up the water with solar energy, and then use heat pump to heat it to 55℃; when enough solar energy is available to heat the water to 55℃, the water is heated directly by solar energy for supply.

In fact, the combination of solar energy and air source heat pump is not necessarily the best scheme, which needs to be calculated according to the specific situation of hot water usage, and also needs to be comprehensively considered according to the environment of the building itself.