Research And Optimization Of Indoor Light Environment Of Cadmium Telluride Photovoltaic Window Buildings

The application of renewable energy is one of the popular ways to solve the current energy crisis.Energy consumption in building operation phase accounts for about 21% of the total energy consumption in China.Building energy consumption is directly affected by thermal performance of building envelope.Because the exterior window is the weak link of thermal performance of building envelope,the energy saving of exterior window becomes the key point of building energy saving.Translucent photovoltaic exterior Windows are one of the integrated technologies of photovoltaic buildings.By combining solar cell modules with transparent envelope,they can not only generate clean electricity by using solar energy,but also provide better lighting quality for the interior and reduce the possibility of glare.Therefore,translucent photovoltaic Windows have certain energy saving potential and advantages,is an effective way to achieve building energy saving.Most of the existing studies focus on the power generation performance,thermal performance and energy consumption of photovoltaic Windows,and relatively few studies on indoor natural lighting.Even if there is research on natural lighting of photovoltaic Windows,the research content is still insufficient.On the one hand,the use of light environment index is too single,the index of the vast majority of scholars only through illumination study on natural daylighting,and considering the characteristic of semi-transparent pv window structure,its indoor light environment is different from the common room window,for indoor occupants visual comfort on the intensity of illumination of threshold value needs to be more accurate to determine the lower limit;On the other hand,the evaluation of indoor light environment should not only focus on visual effects,but also consider non-visual effects such as human circadian rhythm.Therefore,this paper takes cadmium telluride photovoltaic Windows as an example to study the natural lighting of translucent photovoltaic window rooms through visual effects and non-visual effects.This paper will analyze and solve the above problems through experiment and simulation.In the experimental part,an experimental platform was built to carry out visual comfort experiments,and the illumination thresholds of the two rooms were optimized through subjective questionnaire survey.Then,the light environment evaluation indexes under typical meteorological conditions were tested,including horizontal illumination of working surface,vertical illumination of human eye,color temperature and color rendering index,and the uniformity of horizontal working surface and glare probability were calculated according to the illumination value.Finally,using the actual test data and fuzzy algorithm to compare the indoor light environment quality of cadmium telluride photovoltaic window and ordinary window room.Ectoect and Daysim software were used for numerical simulation.The reliability of the daylighting model was verified by using water plane illuminance data under typical meteorological conditions.On this basis,for cold areas,ordinary Windows with different structures and cadmium telluride photovoltaic Windows with different transmittances are selected to simulate and optimize indoor lighting performance from the design parameters such as building depth and window-wall ratio,so as to maximize lighting quality.The research conclusions are as follows:(1)Due to the selective absorption of solar radiation by cadmium telluride photovoltaic Windows and ordinary glass Windows in the visible band,the natural lighting threshold of ordinary Windows cannot be completely applicable to Cadmium telluride photovoltaic Windows.According to the subjective questionnaire,the lower limit and upper limit of natural lighting illumination of Cadmium telluride photovoltaic Windows are determined to be 500 lx and2200lx,respectively.The threshold value of ordinary window illuminance is300-2000 lx.(2)Based on the measured data and combined with fuzzy comprehensive evaluation method,the indoor light environment evaluation of cadmium telluride photovoltaic window and common window room was carried out.The results showed that the light environment evaluation of cadmium telluride photovoltaic room was "excellent",and that of common glass window room was "good".In contrast,the cadmium telluride photovoltaic room has a more comfortable natural light environment.(3)The variation trend of non-visual effects is similar to that of vertical illuminance at the eye,which means that the working plane of cadmium telluride photovoltaic window room which is far away from the window can hardly meet the minimum requirements of non-visual in some time periods,while the non-visual requirements can be better met in ordinary window room due to the high glass transmittance.(4)In order to improve the quality of indoor lighting,the depth to window wall ratio of cadmium telluride photovoltaic window building in cold climate was simulated and optimized.The results show that the indoor light environment is the best when 40% transmittance cadmium telluride photovoltaic Windows are used at depths of 3m,4m,5m and 6m,respectively,and 40%,50%,50% and60% window to wall ratio are used.10% and 20% transmittance Cadmium telluride photovoltaic Windows at 3m,4m,5m and 6m depth,60% of the window wall ratio,the best indoor light environment.