Feasibility And Optimization Analysis Of Distributed Photovoltaic Power Generation In Buildings With Phase Change Materials

Net Zero Energy Building(NZEB)is considered as a way to meet energy demand using renewable energy to solve the worsening energy consumption problem of buildings.Distributed photovoltaic power generation is one of the important technologies in NZEB design.Its application in buildings will effectively relieve the pressure of power supply caused by the development.At present,the development of distributed PV in Hunan Province is relatively slow.More in-depth research on system performance and economic and environmental assessment is needed.Phase Change Material(PCM)is an environmentally friendly material with excellent energy storage characteristics.Its application in buildings is a research hotspot,which is able to homogenize the time-by-time load of buildings.The introduction of PCM in photovoltaic power generation system,using PCM to reduce the indoor load of the building and delay the peak load,is expected to alleviate the contradiction between the intermittent supply of solar energy and the air conditioning load of the building in terms of time and demand,and achieve the purpose of energy saving and emission reduction.This paper proposes a coupled application of phase change energy storage technology and distributed photovoltaic(PV)power generation technology for building energy efficiency.Firstly,an experimental platform for a building with PCM and PV system is constructed to collect hourly meteorological data,system power generation and building thermal performance parameters.EnergyPlus software is used to simulate the air conditioning electric load characteristics of buildings.System Advisor Model software is used to simulate PV power generation characteristics.The reliability of building model and PV power generation model are verified by experimental data.Secondly,we simulated the load and power generation of the integrated phase change-PV system with PCM volume fraction of 0 vol.%,2.6 vol.%,3.9 vol.%and 5.2 vol.%,respectively.The results showed that the phase change energy storage technology reduces the building electric load demand by about 0.015 kW per hour,and the peak electric load is delayed by 1 h on average.The greater the PCM usage,the smaller the impact of load change on the grid.However,the integrated system has the problems of supply and demand imbalance and peak mismatch.Unavoidable interactions between the PV system and the grid are observed.Therefore,the system is optimized with three strategies:adding batteries to match the peak supply and demand with the aim of a higher self-generation and self-balancing rate;adding PV panels to make the supply meet the demand at all times;and using battery charging and discharging control strategies to increase system independence and battery safety.The self-generation and self-use rate of the optimized building with PCM is 0.41%higher than that of the reference building,which indicates its higher economic performance.By simulating and analyzing the battery charge states of buildings,it is concluded that distributed PV systems in buildings with PCM need to be equipped with larger capacity batteries.Finally,the economic feasibility and environmental performance of PV power system in buildings with PCM are explored.The dynamic payback period of the integrated system with 5.2 vol.%PCM is calculated to be 18.57 years,which is about 0.5 years longer than the payback period of the reference building.The kilowatt cost is about 0.03 Yuan/kWh higher.However,the use of PCM reduces 0.1584 kg/m2 of carbon emission and improve the sustainable competitiveness of the system.