The impact of building-integrated photovoltaics on the energy demand of multi-family dwellings in Brazil

Brazil faces a continuous increase of energy demand and a decrease of available resources to expand the generation system. Residential buildings are responsible for 23% of the national electricity demand. Thus, it is necessary to search for new energy sources to both diversify and complement the energy mix. Building-integrated photovoltaic (BIPV) is building momentum worldwide and can be an interesting alternative for Brazil due its solar radiation characteristics. This work analyses the potential of seven BIPV technologies implemented in a residential prototype simulated in three different cities in Brazil (Natal, Brasília and Florianópolis). Simulations were performed using the software tool EnergyPlus to integrate PV power supply with building energy demand (domestic equipment and HVAC systems). The building model is a typical low-cost residential building for middle-class families, as massively constructed all over the country. Architectural input and heat gain schedules are defined from statistical data (Instituto Brasileiro de Geografia e Estatística—Brazilian Institute for Geography and Statistics (IBGE) and Sistema de Informações de Posses de Eletrodomésticos e Hábitos de Consumo—Consumer Habits and Appliance Ownership Information System (SIMPHA)). BIPV is considered in all opaque surfaces of the envelope. Results present an interesting potential for decentralized PV power supply even for vertical surfaces at low-latitude sites. In each façade, BIPV power supply can be directly linked to local climatic conditions. In general, for 30% of the year photovoltaic systems generate more energy than building demand, i.e., during this period it could be supplying the energy excess to the public electricity grid. Contrary to the common belief that vertical integration of PV is only suitable for high latitude countries, we show that there is a considerable amount of energy to be harvested from vertical façades at the sites investigated.     

Compromises between form and function in grid-connected,building-integrated photovoltaics (BIPV) at low-latitude sites

The integration of photovoltaic (PV) modules on building façades and rooftops is an ideal application of solar electricity generators in the urban environment. Maximum annual performance of grid-connected PV is usually obtained with modules tilted at an angle equal to the site latitude, facing the equator. The performance of PV systems not tilted and oriented ideally can drop considerably, depending on site latitude. With grid parity – when the cost of solar electricity becomes competitive with conventional electricity – expected in many countries in the present decade, a more widespread application of PV on buildings is expected, and in this context the main goal of this paper is to demonstrate that good compromises between form and function are possible. In this work we compare the annual energy generation of a curved BIPV system installed as a car port rooftop, with an ideally-oriented and tilted, flat BIPV system installed as a building’s rooftop cover at a low-latitude site (27°S). For the one-year period analysed, the curved-shape BIPV system annual yield was 12% lower than that of the reference BIPV system, and during the summer months (November to February), the curved BIPV installation presented a higher energy yield than the latitude-tilted generator. With these results we show that a good compromise can be reached between form and function in BIPV systems.     

关于光伏建筑一体化的几点思考

通过案例对光伏建筑一体化的形式进行分析比较,认为光伏建筑一体化的形式应均衡功能、经济、技术和美观等各方面的因素,而并非结合的程度越高越好。根据光伏产品的市场发展,判断光伏构件的设计重点应放在光伏电池组件的维修和更换上,而不是注重延长光伏电池组件的寿命。为解决现有PV构件的弊端,设计了一种便于维修和更换的建筑光伏构件。     

Techno-economic performance analysis of the smart solar photovoltaic blinds considering the photovoltaic panel type and the solar tracking method

In urban areas with dense buildings,it is expected that the building-integrated photovoltaic( BIPV) system,will become widespread. Especially,the solar photovoltaic blinds( SPB),which can block the sunlight coming into the room and produce electricity,is emerging as a new technology trend. To facilitate the installation of the SPB,this study analyzed the techno-economic performance of the smart SPB considering the PV panel type and solar tracking method used. Towards this end,this study conducted experiments using the developed smart SPB,as well as a comparative analysis in terms of the techno-economic aspects based on the experiment results. The analysis results of this study were as follows: at the same cost,( i) the monocrystalline silicon( mono-Si) PV panel generated 350. 5% more electricity than the amorphous silicon( a-Si) PV panel; and( ii) the direct solar tracking system generated 12. 9% more electricity than the indirect solar tracking method.Accordingly,the mono-Si PV panel and the direct solar tracking method were selected for the optimal smart SPB. The installation of the smart SPB with the proposed optimal design on the south-facing window of buildings can be helpful for raising the electricity selfsufficiency rate of buildings by up to 20. 3%.     

A heat pipe photovoltaic/thermal (PV/T) hybrid system and its performance evaluation

Building-integrated photovoltaic/thermal (BIPV/T) system has been considered as an attractive technology for building integration. The main part of a BIPV/T system is PV/T collector. In order to solve the non-uniform cooling of solar PV cells and control the operating temperature of solar PV cells conveniently, a heat pipe photovoltaic/thermal (PV/T) hybrid system (collector) has been proposed and described by selecting a wick heat pipe to absorb isothermally the excessive heat from solar PV cells. A theoretical model in terms of heat transfer process analysis in PV module panel and introducing the effectiveness-number of transfer unit (?-NTU) method in heat exchanger design was developed to predict the overall thermal-electrical conversion performances of the heat pipe PV/T system. A detailed parametric investigation by varying relevant parameters, i.e., inlet water temperature, water mass flow rate, packing factor of solar cell and heat loss coefficient has been carried out on the basis of the first and second laws of thermodynamics. Results show that the overall thermal, electrical and exergy efficiencies of the heat pipe PV/T hybrid system corresponding to 63.65%, 8.45% and 10.26%, respectively can be achieved under the operating conditions presented in this paper. The varying range of operating temperature for solar cell on the absorber plate is less than 2.5 °C. The heat pipe PV/T hybrid system is viable and exhibits the potential and competitiveness over the other conventional BIPV/T systems.     

武汉国际博览中心屋面太阳能光伏发电应用研究

武汉国际博览中心项目为武汉市最大的公共建筑.以武汉国际博览中心项目为背景,进行了屋面太阳能光伏发电技术难点分析,并介绍太阳能光伏系统关键技术,包括光伏组件铺设场地选择、光伏建筑一体化设计、并网系统设计、BIM技术等相关保障技术,最后对项目节能效果进行分析.武汉国际博览中心屋面太阳能光伏发电系统达到了发电、保温节能、装饰的目的,也对其他相关大型项目起到示范作用.     

The financials of constructing a solar PV for net-zero energy operations on college campuses

The LACCD has a goal of establishing net-zero energy operations across its nine campuses. The project faces many challenges, including limited open areas for installing solar PV, increasing energy consumption challenges associated with campus energy growth and the high cost of installing solar PV. A previous study by Kwan and Hoffmann (2010) found that the LACCD would need to install a 9.5 MW solar PV array in order to meet total campus energy demand on a college campus through the year 2020. This paper attempts to evaluate the financial feasibility of such a project, taking into account the current local, state and federal renewable energy incentives available. We find that despite the availability of financial incentives by local municipal utility companies including installation rebates and net metering, the cost of electricity generated by solar PV still remains approximately 30% higher than electricity generated by fossil fuels. We also find that the optimal solar PV array size from a financial standpoint is one that is sized to generate and meet all electrical demand during sunlight hours. Any array larger than this yields diminishing returns. Finally our analysis examined the influence of per kW installation cost and found that only when prices dropped to $3.00 per installed watt did a net-zero energy solar PV array have an NPV of 0.     

光伏建筑一体化(BIPV)的应用

光伏建筑一体化(BIPV)是光伏技术的热点,具有许多优势。本文介绍了光伏建筑一体化的几种方式:太阳能瓦、晶体硅光伏玻璃、非晶硅薄膜光伏玻璃,及其应用范围。阐述了太阳能光伏电池板、控制器、逆变器等的设计原则和光伏发电系统的两种运行方式:独立运行和并网运行,最后给出了某光伏玻璃发电系统年发电量的统计。     

光伏遮阳板与建筑一体化的综合节能效果分析

以长沙地区典型办公建筑为对象,耦合建筑负荷计算,建立了光伏遮阳板的传热和发电模型,模拟了全年建筑能耗和系统产电量.分析了光伏遮阳板在建筑不同朝向以不同倾角和宽度安装时,系统的遮阳和产电的综合节能效果.研究结果表明:光伏遮阳极倾角从0°～40°变化时建筑节能量增加幅度较大,而倾角大于40°时变幅趋缓;系统东、西向安装时的单位面积光伏板的建筑节能效果优于南向安装,倾角小于45°时南向安装的系统产电量最大.研究结果为光伏遮阳板与建筑一体化技术的优化和推广应用提供了有益的参考.     

重庆地区建筑一体化太阳能发电系统经济性浅析

太阳能作为迄今人类所认识的最清洁的可再生能源,与建筑一体化将在建筑节能中起到十分重要的作用。重庆位于四川盆地,由于日照较少,全年太阳总辐射也少,因此,在重庆地区利用太阳能发电的经济性有待研究。本文介绍了太阳能光伏屋顶系统,分析了重庆地区太阳辐射情况,并利用Hybrid2仿真软件对重庆地区光伏发电系统的经济性进行了研究。     

Study on thermal performance of semi-transparent building-integrated photovoltaic glazings

This paper presents a one-dimensional transient heat transfer model, the Semi-transparent Photovoltaic module Heat Gain (SPVHG) model, for evaluating the heat gain of semi-transparent photovoltaic modules for building-integrated applications. The energy that is transmitted, absorbed and reflected in each element of the building-integrated photovoltaic (BIPV) modules such as solar cells and glass layers were considered in detail in the SPVHG model. Solar radiation model for inclined surface has been incorporated into the SPVHG model. The model is applicable to photovoltaic (PV) modules that have different orientations and inclinations. The annual total heat gain was evaluated by using the SPVHG model. The impacts of different parameters of the PV module were investigated. It was found that solar heat gain is the major component of the total heat gain. The area of solar cell in the PV module has significant effect on the total heat gain. However, the solar cell energy efficiency and the PV module's thickness have only a little influence on the total heat gain. The model was also validated by laboratory tests by using a calorimeter box apparatus and an adjustable solar simulator. The test results showed that the simulation model predicts the actual situation well.     

Effect of building integrated photovoltaics on microclimate of urban canopy layer

Building integrated photovoltaics (BIPV) has potential of becoming the mainstream of renewable energy in the urban environment. BIPV has significant influence on the thermal performance of building envelope and changes radiation energy balance by adding or replacing conventional building elements in urban areas. PTEBU model was developed to evaluate the effect of photovoltaic (PV) system on the microclimate of urban canopy layer. PTEBU model consists of four sub-models: PV thermal model, PV electrical performance model, building energy consumption model, and urban canyon energy budget model. PTEBU model is forced with temperature, wind speed, and solar radiation above the roof level and incorporates detailed data of PV system and urban canyon in Tianjin, China. The simulation results show that PV roof and PV façade with ventilated air gap significantly change the building surface temperature and sensible heat flux density, but the air temperature of urban canyon with PV module varies little compared with the urban canyon of no PV. The PV module also changes the magnitude and pattern of diurnal variation of the storage heat flux and the net radiation for the urban canyon with PV increase slightly. The increase in the PV conversion efficiency not only improves the PV power output, but also reduces the urban canyon air temperature.     

建筑一体化电热冷联产光伏组件能量特性研究

传统太阳能光伏或光热建筑一体化只能为建筑提供单一电能或热能。通过研究一种集成发电、集热、制冷3种功能的建筑一体化电热冷联产光伏组件,对其夏季工况下能量特性进行了实际检测。结果表明:白天,组件集热同时能有效降低光伏电池温度,组件工作温度高于环境温度约8~16℃,发电和集热效率分别为14.1%~13.7%和40.1%~15.7%;晴朗夜间,组件通过对流和辐射两种传热方式进行散热制冷,总制冷功率为26.0~268.5 W/m~2。电热冷联产光伏组件适合与热泵结合,为建筑提供所需能源。     

太阳能光伏技术与应用

本文从太阳能光伏技术应用的现实意义出发,论述了光伏技术的基本原理、系统组成、应用方式、安装要求等,分析了光伏技术与绿色照明在建筑领域的应用现状及前景,旨在对太阳能光伏技术的应用、发展起到积极的推动作用。     

Building-integrated photovoltaics (BIPV) in architectural design in China

Building-Integrated Photovoltaics (BIPV) are one of the best ways to harness solar power, which is the most abundant, inexhaustible and clean of all the available energy resources. This paper discusses issues concerning BIPV in architectural design in China, including how to choose between BIPV and building-attached photovoltaics (BAPV), whether it is necessary for photovoltaic components to last as long as buildings and how to design BIPV structures. The paper shows that we should consider the function, cost, technology and aesthetics of BIPV, rather than solely the high integrations. According to developments in technology and markets, photovoltaic structures and design should be focused on the maintenance and replacement of photovoltaic cell modules, rather than simply prolonging their lives. To solve problems associated with the existing photovoltaic structures in China, we design a building photovoltaic structure that allows convenient maintenance and replacement of photovoltaic components.     

Modeling of energy performance of a house with three configurations of building-integrated photovoltaic/thermal systems

A theoretical and experimental study of energy performance of three different open loop air heating building-integrated photovoltaic/thermal (BIPV/T) systems that utilize recovered heat for home heating is presented. The configurations are: Configuration 1: base case of unglazed BIPV with airflow under it; Configuration 2: addition of 1.5 m vertical glazed solar air collector in series with Configuration 1; Configuration 3: addition of a glazing over the PV. The model developed has been verified against experimental data from a solar research house for Configuration 1. Obtained relationships for BIPV/T system exiting air temperature as function of solar irradiance and air speed in PV cavity may be used for developing fan airflow control strategies to achieve desired outlet air temperature suitable for different applications. For Configuration 1, preheated air is suitable for HVAC system and domestic hot water (DHW) preheating. Higher outlet air temperatures of the PV cavity suitable for DHW might be achieved by utilizing Configurations 2 or 3. With Configuration 2, significant outlet air temperatures are achieved in winter along with enhanced thermal efficiency making it suitable for coupling with a rockbed heat storage. Finally, Configuration 3 significantly reduces electricity production and may lead to excessively high PV panel temperatures.     

深圳火车北站太阳能光伏发电系统设计

分析深圳市的太阳能资源状况．介绍深圳火车北站太阳能光伏发电系统采用的光伏建筑一体化（BIPV）形式,光伏组件的选择,与建筑屋面配套的安装方式与安全性考虑,光伏电气系统的安装、控制、保护、防雷与并网方式．分析阴影遮挡对光伏器件的影响,竣工以来的发电量情况。     

光伏建筑一体化建筑空调负荷特点及节能对策分析

认为光伏建筑一体化和并网发电将是人口密集的城市利用太阳能的主要形式。分析了光伏一体化建筑中光伏器件对空调系统的影响、此类建筑空调负荷的特点及计算方法问题,从复合能量系统的角度提出了有利于空调通风系统节能发展的新策略。     

杭州东站10MWp光伏建筑一体化示范项目简介

通过介绍杭州东站10MWp光伏建筑一体化项目,推广太阳能发电用户侧并网或高压上网并网等成熟可靠的先进技术;利用现有、新建或改扩建公共项目屋顶,建设太阳能光电建筑,同时与建筑风格有效结合,实现建筑与太阳能一体化。     

太阳能光电建筑设计中的日照分析

随着太阳能光伏发电技术的进步,光伏发电与建筑一体化（简称BIPV）成为太阳能发电的主要利用形式之一。本文运用Ecotect生态大师展开BIPV前期方案设计,通过对建筑自身特点、地理环境、气候条件等进行计算机模拟计算,为建筑、机电等后期专业深化设计提供科学依据。本文以某市博物馆BIPV方案设计为例,通过分析太阳能辐射和阴影,对系统装机容量、光伏方阵设计等统筹优化,指导工程师在方案阶段的决策。