Model Optimization And Application Simulation Of Chinese Solar Greenhouse Integrated With Photovoltaic Panels

The integrated application of agriculture and PV is an important direction for the development of horticultural agriculture,but the structure of energy-saving solar greenhouse limits the installation of large-size photovoltaic panels on it,for the prominent contradiction between PV generation and crop photosynthesis.In order to solve the problem,this paper optimized the form of PV panels based on the demand of facility agriculture production from the perspective of model analysis and application simulation:1.Construct the sky illumination model.The relationship among‘weather type’,‘dome height（cloud base height）’and‘sky background brightness’is excavated from literates.When the weather is particularly clear,the cloud base height H=8000m,the sky background brightness of the solar area E_SUNis 20 times of the sky background brightness of the non-solar area E_sky;in normal weather conditions,the cloud base height H=3000m and E_SUN/E_SKY=7;and in cloudy weather conditions,the height of the cloud base is H=1000m and E_SUN=E_SKY.By judging the range of the visible sky and integrating the amount of incoming light,the daylighting at any point in the greenhouse can be compared.2.Size and layout optimization of PV panels for integrated application with energy-saving solar greenhouse.Based on the sky illumination model,a grid composed of 9mm wide PV panels（GPV panels）is installed on the relatively flat part of the energy-saving solar greenhouse’s front roof above 2m height,the intervals are controlled between 0-20cm,and the light transmittance on the bottom can be controlled from 0 to more than 90%and relatively uniform（the difference of the light transmittance between the areas corresponding to the panel and to the interval is less than 4%）.Such a PV grid can meet the lighting needs of different crops,and will not block the sun and its surrounding sky for a large area and a long time.3.Simulation verification with CFD to the integrated application of GPV with energy-saving solar greenhouse.A geometric model including the interior space of the greenhouse,the back wall and 1m deep topsoil is constructed in Fluent,setting continuous large-size PV panels（1m wide）and GPV panels（9mm wide and 0.15m interval）on the front roof,the external atmospheric temperature of the greenhouse and the daily constant temperature layer temperature of the soil（1m below the surface）are selected as the main boundary conditions,and the S2S model is used for simulation verification,the feasibility and superiority of GPV panels are verified.4.Imitate the micro-grid scheduling in greenhouse integrated with PV.With the theory of‘smart grid’,this paper studies the power generation,energy scheduling and benefits of PV system integrated onto greenhouse.Combined with the actual production of greenhouse,the demand side load is divided into non-time-shifting power and time-shifting power,the energy is dispatched according to the principle of‘local consumption and sharing the surplus’,the battery capacity is configured according to the assumption of‘self-sufficiency in peak power consumption at night’,with the start-up time of time-shifting powers as optimization factors,PSO optimization algorithm is used to seek the maximum benefit of the system under certain policy conditions.On this basis,the prediction and guidance of micro grid system operation can be realized by selecting typical weather data in specific areas and formulating micro-grid operation schemes under different weather conditions.The results show that replacing large-size PV panels with GPV panels can effectively resolve the contradiction between power generation and crop photosynthesis in energy-saving solar greenhouse,it can also provide beneficial support for the development of horticultural agriculture in the direction of modernization and electrification.