Energy Saving And Emission Reduction Analysis Based On A Rural Residential BIPV/T System

For the cold rural areas in the north,the electricity is dependent on the power grid,and most areas still use traditional fossil energy for heating.In the process of heating or electricity use,certain emissions will be generated directly or indirectly,causing pollution to the environment.The country has been exploring alternative clean energy.As a clean renewable energy,solar energy can be directly converted into electric energy and heat energy for people to use when it shines on PV/T modules,which has its unique advantages.Therefore,from the perspective of building energy conservation and emissions reduction,a ground source heat pump system combined with building integration Photovoltaic/Thermal（BIPV/T）is proposed in this paper.The electricity generated in the system will meet users’own needs.At the same time,combined with auxiliary equipment such as ground source heat pump,photovoltaic waste heat is used for heating and domestic hot water production,which is the focus of the research.Firstly,the ground source heat pump composite BIPV/T system is established and different operating modes are proposed for heating season and non-heating season to ensure the normal operation of heat supplement and heat extraction.The system is applied to a ordinary building to form a new photovoltaic building（later called photovoltaic building）,and a new heat transfer model of photovoltaic building envelope is established.At the same time,the hourly heat load,natural room temperature and other parameters of the photovoltaic building and the ordinary building are calculated by De ST software.It is found that compared with ordinary buildings,the average hourly heat load and the maximum hourly heat load in the heating season of photovoltaic buildings are reduced by14.2%and 11.3%respectively,while the average natural room temperature in January is increased by 1.39℃,indicating significant energy saving effect.Secondly,the TRNSYS model of the system is established,and the system was optimized according to the volume of the water tank and the cooling flow.Then,the annual power generation and power consumption of the system were simulated.Compared with a single photovoltaic power generation system,the ground source heat pump composite BIPV/T system can generate 3271.2kwh more electricity in the whole non-heating season by means of buried pipes and water tank cooling,which obtains a net generation income of 1947.2kwh.The hourly temperature changes of soil after one year and 20 years were simulated to ensure the thermal balance of soil.After cooling,the temperature of PV/T modules on the envelope are mostly controlled between 20℃and 40℃,and the temperature is relatively ideal.The results show that the system can extend the life of PV/T modules by cooling,but also could generate more electricity.Finally,through the detailed calculation of power generation and power consumption of several systems.It is found that compared with ordinary household electric heating system,the ground source heat pump composite BIPV/T system can reduce the energy consumption of heating and domestic hot water by 65.6%and 17.2%respectively,while photovoltaic+electric heating system can only reduce the energy consumption of heating by 6.8%.According to the calculation and simulation results,compared with electric heating system,the two systems can save 29453.2kwh and 19444.1kwh of electricity per year respectively.In the whole life cycle,the ground source heat pump composite BIPV/T system and photovoltaic+electric heating system can reduce the coal consumption of179.61t and 118.57t respectively.Meanwhile,dust,NO_x,SO₂,CO₂ and other pollutants can be reduced by 2.87t,1.80t,3.05t,441.83t and 1.90t,1.19t,2.02t,291.68t respectively.The initial investment of ground source heat pump composite BIPV/T system and photovoltaic+electric heating system is 125527 yuan and 69466 yuan respectively.The investment recovery period is 8.8 years and 7.5 years respectively,and the total life cycle income is 159605 yuan and 114720 yuan respectively.From the point of view of the payback period,the ground source heat pump-BIPV/T system is slightly inferior,but from the point of view of the whole life cycle,the ground source heat pump composite BIPV/T system brings higher income and has better environmental benefits,so it has better system superiority.The proposed system relives the pressure of the power grid without producing any emissions,and provides a new reference and choice for the spontaneous power supply and heating for the cold rural areas in the north.