Building-integrated Photovoltaic Array Research Articles

Towards a high resolution simulation framework for building integrated photovoltaics under partial shading in urban environments

This paper presents a framework for modeling the performance of photovoltaic (PV) systems, which is intended to be used in the design, optimization, and deployment of PV systems in urban environments. Urban PV and building integrated PVs (BIPV) are a crucial component of the transition to a low-carbon society. However, existing frameworks for simulating PV systems accurately characterize PV under partial shading, leading to performance gaps with systems deployed in environments such as cities where shading is more common than in large open fields. In this paper, we extend a framework from literature for modeling parametric BIPV arrays using a power model that characterizes IV-curves at the PV cell. We describe the framework and perform a validation against a measured rooftop PV array dataset. We then evaluate the extended framework to other PV modeling and simulation frameworks found in the literature through the simulation of a simplified facade under various levels of shading. Results show that the extended framework is necessary to account for partial shading, but there may be use cases when lower resolution frameworks may be just as accurate. Amongst the frameworks a range of predicted power outputs under the shading conditions was observed; from 6% to 846% with a mean of 162% from the other frameworks relative to the proposed framework. The range is due to the extensive set of conditions tested, where it was observed that in conditions where shading is present but sparse, there is a larger range of predicted output from the various frameworks. Whereas in conditions where shading coverage is high this range is lower. Lastly, we demonstrate the use of the framework on three arrays. Again it was observed that homogeneous shading conditions may not require the level of resolution provided by the proposed framework, while heterogeneous could benefit the most from the approach. This indicates, and is discussed in the paper, that modelers should consider the shading conditions present when deciding on which framework to apply.

Critical Comprehensive Performance Analysis of Static BIPV Array Configurations to Reduce Mismatch Loss and Enhance Maximum Power Under Partial Shading

On-grid and off-grid building integrated photovoltaic (BIPV) systems require a large size BIPV array (LSBA) as their major renewable energy generator. Partial Shading (PS) significantly contributes to power loss in LSBA. One effective solution to mitigate the adverse effect of PS in LSBA is the application of fixed or static BIPV array configurations (BIPV-ACs). This research article critically compares the different fixed BIPV-ACs for modelling, designing and critical analysis of LSBA. Different existing and proposed fixed BIPV-ACs are modelled and simulated in MATLAB/Simulink under six dissimilar cases of PS patterns. Further, the performance is investigated in terms of global maximum power point (G-M-PP), mismatch loss (ML), fill factor (FF), efficiency (η), relative power loss (RPL) and relative power gained (RPG) to identify the best BIPV-AC. Experimental justification of simulation results under two PS pattern cases is reported. The best BIPV-ACs with high G-M-PP and low ML are Total-Cross-Tied (TCT), Triple-Tied (TT), Modified Triple-Tied (M-TT) and Hybrid Bridge-Linked Total-Cross-Tied (H-BL-TCT). Finally, the comprehensive critical analysis reveals that the H-BL-TCT array is the best performing array with low ML, high FF and η, and high G-M-PP with low wiring requirements than the TCT array. The simulation results conclude that the H-BL-TCT array improves G-M-PP by 6.40 %, reduces ML by 4.23 %, and improves FF & η by 4.58 % and 0.54 %. The experimental results infer that the H-BL-TCT array improves G-M-PP by 0.83 %, reduces ML by 0.75 %, and improves FF & η by 0.88 % and 0.09 %.

A new hybrid BIPV array for enhancing maximum power with reduced mismatch losses under extreme partial shading scenarios

ABSTRACT Building integrated photovoltaic (BIPV) systems are gaining major attention in modern cities due to the absence of free space to install ground-mounted photovoltaic (PV) plants. A large interconnected BIPV array (liBA) is essential for standalone and grid-connected BIPV systems. The major problem with liBA is the partial shading (PS) phenomenon that increases the mismatch losses (MmLs) and reduces the maximum power (MP) output. Modelling, simulation, and performance analysis of a novel 7 × 5 and 7 × 8 hybrid triple-tied total-cross-tied (TrTd-TtCrTd) fixed BIPV array for increasing MP with reduced MmLs under extreme PS conditions are the main goals of this research paper. In addition, existing hybrid arrays such as series-parallel total-cross-tied (SePl-TtCrTd), bridge-linked total-cross-tied (BdLk-TtCrTd), and honey-combed total-cross-tied (HnCb-TtCrTd), as well as conventional triple-tied (TrTd) and total-cross-tied (TtCrTd), are compared. The simulation results are also validated experimentally using two PS situations. Finally, the global maximum power point (GlMxPoPt), MmLs, fill factor (FiFa), and efficiency (Effy) are used to evaluate the performance. Under six different extreme PS scenarios, the simulation results show that the proposed 7 × 5 hybrid TrTd-TtCrTd array increases GlMxPoPt by 4.84 %, decreases MmLs by 3.46 %, and increases FiFa and Effy by 2.20 % and 0.34 %, respectively. Under two severe PS scenarios, simulation results show that the proposed 7 × 8 large size hybrid TrTd-TtCrTd array increases GlMxPoPt by 3.43 %, decreases MmLs by 2.29 %, and increases FiFa and Effy by 1.26 % and 0.23 %, respectively. Under two extreme PS scenarios, experimental results indicate that the proposed 7 × 8 hybrid TrTd-TtCrTd solar array increases GlMxPoPt by 2.84 %, decreases MmLs by 2.12 %, and increases FiFa and Effy by 1.82 % and 0.22 %, respectively. The proposed hybrid TrTd-TtCrTd array improves GlMxPoPt, reduces MmLs and improves FiFa and Effy with low wiring requirements under different PS cases.

A Novel Fixed BIPV Array for Improving Maximum Power with Low Mismatch Losses Under Partial Shading

Partial shading is a significant limitation that decreases the maximum power output of large photovoltaic (PV), and building integrated photovoltaic (BIPV) arrays installed in modern buildings. One of the optimum solutions to mitigate the difficulty related to partial shading is applying different interconnected fixed BIPV array configurations. This research article aims to modelling, simulation, and performance analysis of a novel conventional 7 × 8 Quarter-Tied (QrTd) fixed BIPV array configuration under the centre, left staircase, frame, left corner, diagonal, and left side shading pattern cases in Matlab/Simulink. Moreover, a comprehensive study with existing conventional fixed BIPV array configurations such as Series-Parallel (SePl), Bridge-Linked (BdLk), Honey-Combed (HnCb), Triple-Tied (TrTd), Total-Cross-Tied (TtCrTd) array interconnections is also executed. The variable parameters for performance evaluation include global maximum power point (GlMxPoPt), mismatch losses (MmLs), fill factor (FiFa), efficiency (Effy), relative power loss (RlPwLs) and relative power gained (RlPwGn). Experimental validation under two partial shading cases is also reported for the justification of simulation results. The simulation results infer that the proposed QrTd configuration improves GlMxPoPt by 4.31%, reduces MmLs by 3.54%, and improves FiFa & Effy by 2.44% and 0.34%, respectively, under six different shading cases. The experimental results conclude that the proposed QrTd configuration improves GlMxPoPt by 1.62%, reduces MmLs by 1.15%, and improves FiFa & Effy by 0.65% and 0.14%, respectively, under two shading cases. Moreover, the wiring requirement and the wiring losses are also lower in the proposed QrTd configuration than in the TtCrTd configuration.

Analysis of Optimal Configuration of Building Integrated Photovoltaic (BIPV) Array under Moving Partial Shade

Influenced by partial shade, there are power losses induced by irradiation reduction, photovoltaic (PV) modules mismatch and maximum power point tracking (MPPT) failure. In order to raise power generation efficiency of building integrated PV (BIPV) power station, typical series-parallel PV array controlled with centralized MPPT is taken into consideration. Simulation model is constructed to describe the output characteristic of PV array under complex partial shade conditions. Due to bypass/blocking diodes, there are multiple peaks on P-V characteristic curve under partial shade. Potential power losses under partial shade are analyzed and divided into three parts respectively. Simulation results demonstrate that there are considerable power losses induced by PV module mismatch under determined tangible partial shade lasting for long time. Optimal configuration of BIPV array are brought forward to minimize PV module mismatch power loss for moving shade conditions, and it is also suitable to large desert or hillside PV power stations.

Performance optimization of the BIPV powered electrolyser and fuel cells installation

A practical multipurpose implementation of hybrid renewable energy system completely located within the building and including building integrated photovoltaic (BIPV) solar power energy source is presented. The system uses solar photovoltaic electricity generated by the building skin to produce hydrogen for fuel-cells, which in turn, when converted to energy in fuel cells, may be used to supply additional power to the building (or fuel cell vehicles) when solar power is not sufficient, for example at night or in periods of low insolation. Electricity generated from 8.2kWp BIPV array optimally supplies the electrolyser near the maximum power point level of the BIPV array. To further optimize hydrogen production, the electrolyser is connected to the local electrical utility, and DC power is provided to the electrolyser through a custom on-board DC power supply that supplements the BIPV array. Performance of the complete installation is optimized to provide continual production at the optimal efficiency level of hydrogen production at constant power. The results obtained from the system operation have shown excellent voltage and current regulation during operation of the electrolyser. The project shows the potential for development of similar building integrated hybrid systems elsewhere with possibilities for inclusion of additional renewable energy sources and added functionality.

Façade–integrated photovoltaics: a life cycle and performance assessment case study

ABSTRACTThe Solaire Building has the first façade building‐integrated photovoltaic (BIPV) array in New York City. This paper presents the life cycle impacts of the Solaire BIPV and extrapolates its performance to other façade systems. Engineering diagrams, detailed material inventories and 5 years of irradiation and actual performance data in 15‐min intervals offer insights into current BIPV construction and performance. The Solaire BIPV employs waste‐stream monocrystalline silicon wafers. Correspondingly, zero energy input was allocated to this BIPV from wafer production, resulting to a very low energy payback time (EPBT) and global warming potential burden (0.8 years and −10.2 g CO2/kWh, respectively). A negative EPBT results from subtracting the impact of the thermally and structurally equivalent concrete and brick wall that the BIPV array replaced. Data from current photovoltaic‐dedicated Si wafer supply were also used; these resulted with an EPBT of 3.8 years and a global warming potential of 61 g CO2/kWh. The performance ratio and EPBT of the Solaire system were compared with those in the International Energy Agency Photovoltaic Power Systems Task 2 inventory database. The drawback of façade BIPV is its vertical orientation, receiving lower incident irradiation than rooftop and ground installations. Nevertheless, BIPV offers two main advantages over such installations: it does not require any ‘virgin’ land for its operation, and it replaces structural units, thus avoiding the cost, embodied energy and corresponding emissions related to those. We detail herein how the replacement of traditional cladding materials can offset the performance drawback of BIPV, in terms of environmental burden and EPBT. Copyright © 2012 John Wiley & Sons, Ltd.

Low light conditions modelling for building integrated photovoltaic (BIPV) systems

The low irradiance efficiency of photovoltaic modules is important to the optimization of BIPV systems. When photovoltaic modules are integrated into a building, architectural design considerations compete with maximizing photovoltaic energy production. As a result, BIPV arrays are often not facing south and are frequently mounted vertically. Under these conditions, a greater portion of the total sunlight striking the array is diffuse or at high angles of incidence. In northern latitudes a significant amount of the total yearly energy is produced at low light levels. A grid-connected array of BIPV modules integrated into the BCIT Technology Centre building in Burnaby, B.C. was used for assessing the accuracy of an energy performance model developed for BIPV systems. The BIPV system uses AC modules and a computerized data acquisition system for monitoring the performance of modules and inverters. The performance model was developed from analysis of the open circuit voltage, maximum power point voltage and maximum power point current of the individual modules comprising the BIPV array. The algorithm for calculating power output of the photovoltaic array is derived from the ideal diode equation using the single diode model of a photovoltaic cell. An empirically derived parameter modifies the equation. Once the parameters for different module technologies are established, it is possible to compare their annual performance in a BIPV system.

A modelling method for building-integrated photovoltaic power supply

Models of photovoltaic (PV) module electrical characteristics are well developed, because of the precise knowledge of the physics of semiconductor behaviour. The PV cell current-voltage characteristic is well known, and used in many models of array output. However, in many practical cases such as building-integrated photovoltaics, a model of power output only is required. Current-voltage revious researchers on which particular model should be used. This contrasts with the case of the diode model for I-V characteristics. In this work, an ef. ciency model of power output will be developed based on an adaptation of the established PV. fill factor method, and attempts are made to ground the irradiance and temperature characteristics in established theory in order to make a general PV power ef. ciency model. The model is validated using measured data from a 39.5-kW building-integrated PV array.