Search

• Electrical-thermal modeling of power converter as part of a BIPV library in Modelica. • Power converter integration in BIPV module frame in a 'plug and play' configuration. • Experimental validation using a converter prototype tested in a climate chamber. • Improved accuracy compared to TRNSYS power conditioner across all KPIs. • Converter placement inside the frame strongly a?ects the components temperature. European legislation on building performance and energy efficiency pushes the shift towards minimizing the environmental footprint of buildings. Building-integrated photovoltaics (BIPV) is a promising technology that can accelerate the transition to energy-neutral buildings. Quantifying the potential of BIPV is crucial and one means of obtaining those results is through simulation. The state-of-the-art tools offer either thermal or electrical specialization; in particular, balance of system components (BOS) such as power converters have not been studied in detail within the building simulations BIPV domain. In this paper, a multi-physics model of a BIPV integrated DC/DC converter is developed in the Modelica language, taking into account the thermal and electrical couplings inherent to power electronic systems. The model has been validated using representative outdoor BIPV measurements and a DC/DC converter prototype. It has been found that the proposed model provides reasonable accuracy and outperforms an equivalent power conditioning model in TRNSYS. To demonstrate the model's functionality, two case studies are performed. First, the temperature-dependence of the converter's efficiency and losses is quantified and analyzed and, second, the prominent contributors to the converter losses are identified and discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Rh/v is defined to estimate the potential of solar energy on the vertical area. • Sun-tracking PV shading elements integrated with windows are modeled and analyzed. • Novel optimum sun-tracking methods and cell layout are first proposed. • Annual energy generation and average efficiency are improved by 27.40% and 19.17%. • Optimum sun-tracking methods reveal great ability to protect glare from the sun. Abstract Vertical space bears great potential of solar energy especially for congested urban areas, where photovoltaic (PV) windows in high-rise buildings can contribute to both power generation and daylight harvest. Previous studies on sun-tracking PV windows strayed into the trade-off between tracking performance and mutual shading, failing to achieve the maximum energy generation. Here we first build integrated models which couple the performance of sun-tracking PV windows to the rotation angles. Secondly, one-degree-of-freedom (DOF) and two-DOF sun tracking are mathematically proven to be not able to gain either maximum power generation or non-glare daylighting under reasonable assumptions. Then we derive the optimum rotation angles of the variable-pivot-three-degree-of-freedom (VP-3-DOF) sun-tracking elements and demonstrate that the optimum VP-3-DOF sun tracking can achieve the aforementioned goals. When the restriction of the proposed model is relaxed, the same performance can be achieved by the optimum one-DOF sun tracking with extended PV slats and particular design of cell layout, requiring less complicated mechanical structures. Simulation results of nine global cities show that the annual energy generation and average module efficiency are improved respectively by 27.40% and 19.17% via the optimum VP-3-DOF sun tracking over the conventional perpendicular sun tracking. The proposed optimum sun-tracking methods also reveal better protection against sun glare. The optimum VP-3-DOF sun tracking is also demonstrated to be applicable to horizontal PV windows, as those applied in the sun roof of a glass greenhouse. [ABSTRACT FROM AUTHOR]

This paper presents an integrated bottom-up approach aimed at helping those dealing with strategical analysis of installation of Building Integrated Photo Voltaic (BIPV) to estimate the electricity production potential along with the energy needs of urban buildings at the district scale. On the demand side, hourly energy profiles are generated using dynamic building simulation taking into account actual urban morphologies. On the supply side, electricity generated from the system is predicted considering both the direct and indirect components of solar radiation as well as local climate variables. Python-based Algorithm editor Grasshopper is used to interlink four types of modelling and simulation tools as 1) generation of 3-D model, 2) solar radiation analysis, 3) formatting weather files (TMY data set) and 4) dynamic energy demand. The method has been demonstrated for a cluster of 20 buildings located in the Yasar University in Izmir (Turkey), for which it is found the BIPV system could achieve an annual renewable share of 23%, in line with the Renewable Energy Directive target of 20%. Quantitatively-compared demand and supply information at hourly time step shows that only some energy needs can be met by BIPV, so there is a need for an appropriate matching strategy to better exploit the renewable energy potential. [ABSTRACT FROM AUTHOR]

This study investigates a naturally-ventilated photovoltaic (PV) façade for high-rise buildings by conducting simulation study. Computational fluid dynamics (CFD) approach was adopted for modelling the temperature and airflow distributions around the naturally-ventilated and conventional PV facades of a case building. The simulation results show that the surface temperature of the naturally-ventilated PV façade is obviously lower than that of the conventional PV facade. The PV cell efficiency of the naturally-ventilated PV facade with different tilt angles was calculated by using simulation results and was found to be higher than conventional PV façade. This paper proved that in comparison with conventional PV facade, the naturally-ventilated PV facade can achieve lower surface temperature of the PV module and thus improving its power generation efficiency. However, experimental study and economic analysis still need to be carried out in future for wider application of the naturally-ventilated PV facade. [ABSTRACT FROM AUTHOR]

China's building stock of more or less uniform residential blocks requires energy-, comfort and not at least architectural upgrade, if future demands are to be met and if demolition and thereby loss of valuable resources is to be prevented. Replacement of these buildings is not an option since affordable housing continues to be required in Chinese cities. Comfort requirements are currently increasing from previously undemanding behaviour to more energy-demanding comfort expectations. Retrofit of conditioning equipment in old buildings will lead to a significant increase in energy consumption, if the buildings are not upgraded (insulated, air tightened, etc.). Furthermore, although China is leading in the production of photovoltaic modules, the utilization of building integrated photovoltaic systems (BIPV) is not yet implemented at a significant scale. However, the prevailing building typology is characterized by a southerly orientation, a favourable floor-to-roof ratio, a rather simple building envelope, appropriate floor plans and not at least a roof structure able to carry PV systems. Climates in many areas in China are more favourable for solar energy generation than in other countries, such as Germany, where BIPV is already widely utilized. This paper investigates the potentials of energy upgrade of a building typology representative for a large percentage of the existing Chinese building stock for 26 climates in China. Strategies of “efficiency” (energy-upgrade measures), “consistency” (renewable energy generation and revitalisation of existing structures) as well as “sufficiency” (reduced comfort requirements) are discussed as the pillars of a strong concept for sustainable upgrade of China's existing building stock. [ABSTRACT FROM AUTHOR]

To ensure the cost effectiveness of photovoltaic power plants (PVPPs) it is needed to keep the level of yearly energy production as high as possible. In this context, efficiency and availability of a PVPP have to be checked continuously. The section of a PVPP which deserves more attention is surely the PV array, where many fault conditions can happen (shading, by-pass diode faults, cable interruptions, and so on). A diagnostic tool to detect faults in the PV array is desirable, even if its implementation is critical owing to: the fluctuation of the operating conditions (mainly irradiance), which complicates the instantaneous response investigation and costs and implementation constraints to implement a distributed (at PV module level) or semi-distributed (at string level) monitoring/diagnostic system. Particularly, for BIPV systems, further constraints related to the regular access for inspection and maintenance operations have to be considered. In this paper, the procedure adopted to develop and validate a diagnostic tool can be summarized in four steps: (1) using real data to model the PV array; (2) introducing several fault scenarios on the real PV string and analyzing the relative modifications of the I – V curves; (3) assessment of the meaningful parameters useful to discern the different faults by means of a PV generator (PVG) simulator based on a metaheuristic technique denominated ABC-DE ; (4) proposition of several fault signing tables to assess the PV plant fault diagnostic. [ABSTRACT FROM AUTHOR]

Due to global climate change, building-integrated photovoltaics (BIPV) have been recognized as an effective solution to reduce the dependence on fossil fuels and achieve nearly zero-energy buildings. Nevertheless, BIPV implementation remains a niche development. Various studies have discussed the barriers to BIPV implementation. However, very few studies have endeavoured to investigate the complex interrelationships among the barriers to BIPV implementation in Singapore. In this study, the barriers to BIPV implementation in Singapore are first addressed by a literature review and then verified by local academics and industry experts. Additionally, the interpretive structural modelling (ISM) approach is deployed to investigate the contextual interrelationships among the identified barriers. Then, a hierarchical structure of the barriers is developed through the ISM method, and the barriers are categorized by clusters, with cross-impact matrix multiplication applied to the classification technique. In addition to the economic-related issues proposed by previous research, which has concentrated on nonspecific BIPV implementation barriers, the findings show that the lack of professionals and the absence of cost-effective BIPV products and design tools should be given specific attention for BIPV implementation in Singapore. The findings offer valuable information on the overall structure and interrelationships among the barriers to Singapore's BIPV industry, and a three-step plan for unlocking the potential of BIPV implementation is proposed. The findings also have implications for future research and for obtaining effective scientific and administrative solutions to facilitate BIPV deployment in Singapore. [ABSTRACT FROM AUTHOR]

Progress in development of building-integrated photovoltaic systems is still hindered by the complexity of the physics and materials properties of the photovoltaic (PV) modules and its effect on the thermal behavior of the building. This affects not only the energy generation, as its active function and linked to economic feasibility, but also the thermal insulation of the building as part of the structure's skin. Traditional modeling methods currently presents limitations, including the fact that they do not account for material thermal inertia and that the proposed semi-empirical coefficients do not define all types of technologies, mounting configuration, or climatic conditions. This article presents an artificial intelligence-based approach for predicting the temperature of a poly-crystalline silicon PV module based on local outdoor weather conditions (ambient temperature, solar irradiation, relative outdoor humidity and wind speed) and indoor comfort parameters (indoor temperature and indoor relative humidity) as inputs. A combination of two algorithms (Grammatical Evolution and Differential Evolution) guides to the creation of a customized expression based on the Sandia model. Different data-sets for a fully integrated PV system were tested to demonstrate its performance on three different types of days: sunny, cloudy and diffuse, showing relative errors of less than 4% in all cases and including night time. In comparison to Sandia model, this method reduces the error by up to 11% in conditions of variability of sky over short time intervals (cloudy days). • An AI-based approach is proposed for predicting PV module temperature for BIPV. • The obtained models show relative errors of less than 4% in all cases. • In comparison to Sandia model, this method reduces the error by up to 11%. • GE+DE is a reliable tool easily applicable to non-conventional PV applications. [ABSTRACT FROM AUTHOR]

Dirt accumulation ("soiling") on the surface of photovoltaic (PV) modules may cause significant energy output reductions ("soiling losses"). The adoption of suitable soiling mitigation strategies can make PV deployment more attractive, but it requires the assessment of the magnitude and the seasonal evolution of the soiling losses at local scale, as they are highly dependent on the regional climate, the meteorological conditions and the surrounding environment. For the purpose of estimating them for building integrated and building applied PV systems in Madrid city, Spain (i.e. under Mediterranean climate conditions), a systematic optical analysis was performed during a 15-month experimental campaign using a rooftop soiling test bench which allowed the exposure of multiple glass coupons at two tilt angles of interest (8° and 35°) in a semiurban environment. There was no cleaning schedule so that the exposed glass coupons were simply washed away by the rain. Broadband transmittance reductions (T loss) indicated the occurrence of low soiling losses with yearly-averaged T loss values of 1.49% at 8° and 1.04% at 35°. Regarding the soiling evolution, the local precipitation regime played a fundamental role. Soiling losses were negligible during frequent-rainfall periods, experienced a moderate increment in spring (March–April), and increased notably during the dry summer season, reaching annual maxima in July (5.13% at 8° and 3.89% at 35°). In order to minimize the local soiling losses, performing module cleaning operations at least during these two times of the year is encouraged. Concerning the soiling spectral effects, the optical loss increased towards shorter wavelengths, making wide-bandgap PV technologies more sensitive to local soiling. Finally, when applying PV performance prediction models which include soiling, the recommended local values for the daily soiling rate and the rain threshold are 0.11%/day and 5.3 mm at a tilt angle of 8° and 0.09%/day and 3.3 mm at a tilt angle of 35°. • BIPV-/BAPV-oriented soiling experiment. • Soiling test bench for the long-term exposure of glass coupons. • Assessment of the soiling optical losses on a yearly and a seasonal basis. • The annual rainfall regime played a fundamental role on soiling. • Daily soiling rates and rain thresholds estimated for PV yield prediction tools. [ABSTRACT FROM AUTHOR]

[Display omitted] In this manuscript we review research on the feedback mechanisms between photovoltaic energy production and the urban environment, with an emphasis on synthesizing what is known, while drawing attention to limitations, and indeed errors in, the literature on this topic. We include in our analysis studies on photovoltaic (PV) systems in urban settings – on buildings, as shade structures, or as stand-alone arrays within an urban environment. We further limit the review to studies that investigate how the urban setting affects the performance of PV systems or how PV systems affect their surrounding urban environment. Our review is based on a systematic search of the literature, which revealed 116 unique articles that addressed the underlying questions in a meaningful way. While there are conflicting results reported across this body of literature, our review and synthesis reveal two key findings: (1) PV can significantly warm the city during the day, provide some cooling at night, and potentially increase energy use for air conditioning of buildings in some climates and building types; and (2) placing PV in an urban setting can adversely affect PV efficiency, reducing overall power production up to 20% in comparison to PV applications in rural settings. It is recommended that future developments of PV technologies focus both on increased efficiency and the need to increase reflection of wavelengths of energy not converted to electricity by the PV cells. Furthermore, designs for urban PV systems should explicitly consider the effects of elevated urban temperatures, pollution, and shading on system performance. [ABSTRACT FROM AUTHOR]

Abstract: The shading-type BIPV claddings can act as power generators as well as external shading devices and insulation panels. There is little available information about the impacts of orientations and inclinations on the combined energy effects of the shading-type BIPV claddings, including the power output of PV modules, the cooling load reduction of windows and concrete walls. It is worth studying the effects of different shading-type BIPV cladding designs on the total energy saving in order to maximize the system’s energy performance. By considering the meteorological conditions in Hong Kong, the energy effect of the shading-type BIPV claddings with different surface azimuth angles, in terms of electricity generation and cooling energy consumption reduction is analyzed in this paper. Based on the investigations, the optimum design of the shading-type BIPV claddings for different orientations can be achieved. [Copyright &y& Elsevier]

Abstract: Building integrated photovoltaic is an art and trend using PV module to replace building material on the outer wall. The semi-transparent c-Si PV module is installed to replace the tiled roof in this study. PV power generation prediction is follow with module performance, installation site and meteorological data. A simple model is created to simulate the power output using PV module thermal model. PV module thermal model is the relation of the module temperature, ambient temperature and solar radiation. In the present study, two parameter linearly regression model is to simulate the power generation in BIPV system. The monthly root-mean -square error (RMSE) is about 4.7%. [Copyright &y& Elsevier]

Compared with traditional photovoltaic (PV) cells, bifacial PV cells can generate electricity on both sides. The study aims to research the electricity generation improvement of bifacial PV module as building envelope, and to find factors affecting its power generation performance in order to optimize it. A prefabricated building was renovated with two facades and the roof installed with bifacial PV modules. A test rig was established to monitor the electricity generation of the bifacial PV facades and roof, as well the indoor illuminance. It was found that the roof had the highest power generation per unit area. The electricity generation of bifacial PV module was simulated and validated. Through the simulation, the electricity improvement of the bifacial PV module was about 4.7%–18.8%. Then the simulation model was used to research the important factors to improve bifacial PV modules. The correlation between indoor light environment and bifacial PV power generation improvement is found. With the increase of reflectivity of the inner surface properly, the improvement of electricity was increased until the reflectivity of the ceiling reaches 0.8. In addition, the best coverage of bifacial PV was found. This study will provide optimization guidance for the application of bifacial PV modules in buildings envelope. [ABSTRACT FROM AUTHOR]

This paper reviews and analyzes technological design options, which have become available to date for BIPV systems on roofs and facades, independently of specific products or building projects. This means that this survey does not analyze existing products or realized buildings, but provides an overview of the technologies for BIPV. The starting point is an analysis of the relevance of BIPV technologies for the decarbonization of energy systems, providing energy for direct use of electricity and sector coupling together with an analysis of the German BIPV market. The paper presents the wide range of technical design options for BIPV systems and categorizes and analyzes them to provide a structured overview. This comprises a detailed analysis of the design options for BIPV modules, in which not only the design options for the PV cell layer were comprehensively investigated, but also the different variants of embedding materials, front and rear cover materials, additional interlayers and electrical module layout. Two fundamental module-level design options were investigated in particular detail: The use of PV cells as basic elements of patterns and the use of color to conceal the PV cells. Subsequently, options for the design of complete electrical systems are reviewed, ranging from sub-module level design parameters to building energy systems. Design options for the constructional integration of BIPV modules in the building envelope complete the review of technological design possibilities. [ABSTRACT FROM AUTHOR]

• Rooftop PV key driver in the PV market, thus modelled in IMAGE IAM. • Global estimated potential 8.3 PWh y−1: 1.5 times residential electricity demand. • Scenarios show key role for rooftop PV but regional characteristics crucial. • Income levels and grid electricity prices dominate regional deployment. • Low-irradiation western Europe better than high-irradiation Middle East. The use of solar photovoltaic has strongly increased in the last decade. A significant part of this growth comes from home owners installing rooftop photovoltaic. Despite this key role, most long-term model-based scenarios do not consider decentralized supply of rooftop photovoltaic but concentrate on utility-scale photovoltaic instead. In this paper, we implement rooftop photovoltaic in the Integrated Assessment Model IMAGE to study its possible role in energy and climate scenarios. We first calculated the global technical and economic potential to derive regional cost-supply curves for rooftop photovoltaic. Next, we have added a new decision in the IMAGE model allowing household investment in rooftop photovoltaic based on the comparison of the whole-sale electricity price with the price of rooftop photovoltaic. The global suitable roof surface area was assessed at 36 billion m2, or 4.7 m2 capita−1, leading to a potential for rooftop photovoltaic of 8.3 PWh y−1, roughly 1.5 times the 2015 global residential electricity demand. In the baseline scenario, adding rooftop photovoltaic could lead to a 80–280% increased share of photovoltaic electricity production in 2050 (i.e. from 6% to 17% in total power production). This increase depends on regional characteristics that are essential to the deployment of rooftop photovoltaic: differences in social-economic and policy factors (capital costs, household income, and electricity prices) are considerably more important than physical factors, such as solar irradiance. [ABSTRACT FROM AUTHOR]