Analysis And Optimization Of Photovoltaic Greenhouse Lighting Environment

Facility agriculture is one of the main jobs in agricultural extension,in which photovoltaic greenhouse has the contradiction between solar power generation and photosynthesis of plants.Different purposes of PV greenhouse have different construction standards,cautiousless investment can cause waste.Combined national policies and economic benefits,this thesis starts on the basis of the formation of photovoltaic greenhouse.It shows that the photovoltaic greenhouse built on farmland should be used for agricultural cultivation.The construction of photovoltaic greenhouse from non-farmland could be used for photovoltaic power generation.The study presented in this thesis is the photovoltaic greenhouse lighting environment based on the above-mentioned viewpoints.At present,photovoltaic greenhouse often adopts the method of laying photovoltaic panels on the roof intermittently to balance the contradiction between photovoltaic power generation and agricultural planting.The ratio of areas to be used as the photovoltaic power generation to those as agricultural planting is different from each other.The invalid areas due to the building construction itself were not appropriately considered.The way of intermittent lay-out would cause different light zones in the greenhouse.It is not known to what extent this shading will affect the growth of plants.This thesis investigated the photovoltaic greenhouse lighting environment based on the idea of building a photovoltaic greenhouse on new land to ensure the return on investment by guaranteeing PV power generation,considering the agricultural production to increase income,designing specialized photovoltaic greenhouse,and assuming that only the roof lights up.DIALux was used to simulate a number of common kinds of photovoltaic panel lay-outs.Simulation was conducted in a sunny day in summer.We obtained the light intensity data and used the average light intensity to determine whether the light conditions is able to meet the growing demand.Then we used the minimum intensity to determine whether there exits an insufficient lighting and the maximum intensity to determine whether there is a light inhibition phenomenun.Based on such analysis,we selected the most representative laying method.The simulation for the conditions of the light intensity in winter and cloundy days was also carried out In order to obtain the data under adverse lighting conditions.The effects of the changing light intensity on the plant growth were also studied.By analyzing and testing the moving velocity of the shadow of the sun on the ground,we found that the size of the PV panels on the roof and the height of the roof could affect the plant growth.We then proposed an optimized model of using the hollowed PV panels and inlaid scattered glass for the PV greenhouse.A new layout of PV panel was then designed.By using this new kind of PV greenhouse structure,it is hope that it can not only guarantee the stable income of PV power generation,but also provide agricultural benefits so as to maintain the healthy development of PV greenhouses.