Tracking and back‐tracking

Lorenzo, E.; Narvarte, Luís; Muñoz, Javier

doi:10.1002/pip.1085

Cited by 67 publications

(38 citation statements)

References 7 publications

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“…One control strategy used for tracking PV plants is the so‐called back‐tracking method, for which shading is completely avoided and losses due to small angle of incidence are minimized. Solutions of back‐tracking for one and two‐axis tracking systems exist , however, the parametric 3D modeling framework developed in this work may help to find solutions for complex system geometries. In addition to back‐tracking, strategies with motion control of individual modules (or module clusters) and their impact on electricity generation can be evaluated.…”

Section: Discussionmentioning

confidence: 99%

“…Module shading can lead to electrical mismatch losses and overheating effects, thereby affecting power output and system reliability . Possible proposed solutions to reduce these adverse effects include optimized PV module distribution and tracker control to circumvent shading or electrical configurations of a PV array to minimize power losses, such as the inclusion of bypass diodes or series/parallel circuit designs .…”

Section: Introductionmentioning

confidence: 99%

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Parametric analysis and systems design of dynamic photovoltaic shading modules

Hofer

Groenewolt

Jayathissa

et al. 2016

Energy Science & Engineering

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Energy Science and Engineering AbstractShading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading systems opens new opportunities for BIPV (building integrated photovoltaics) on façades. A key problem of such systems is mutual shading among PV modules as it can lead to electrical mismatch losses and overheating effects. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film PV modules to simulate electric energy yield of geometrically complex PV applications. The developed method is able to predict the shading pattern for individual PV modules with high spatio-temporal resolution, which is of great importance for electrical system design. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement. The analysis shows, that there is a trade-off between tracking performance and mutual shading of modules. Distance between modules is a critical parameter influencing the amount of mutual shading and hence limiting solar irradiation and electricity generation of PV shading systems using solar tracking. Planning of module string configuration, PV cell orientation, and location of bypass diodes according to partial shading conditions, reduces electrical mismatch losses and results in significantly higher electricity generation. The integration of parametric 3D and electrical modeling opens new possibilities for PV system design and dynamic control optimization. Though the analysis focuses on BIPV, the method is useful for the planning and operation of solar tracking systems in general. 135

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Parametric analysis and systems design of dynamic photovoltaic shading modules

Hofer

Groenewolt

Jayathissa

et al. 2016

Energy Science & Engineering

View full text Add to dashboard Cite

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“…We translated POA irradiance to GHI by assuming the isotropic sky model for the sky diffuse irradiance and using concurrent measurements of diffuse horizontal irradiance (DHI) and direct normal irradiance (DNI) from a nearby rotating shadowband radiometer (RSR) operated by the National Renewable Energy Laboratory. Because tracker rotations are not measured we estimated the angle of incidence on the modules using a generic algorithm for singleaxis tracking (Lorenzo et al, 2011). Even with the use of measured DHI and DNI, the estimated GHI profiles were not well-matched with the output of available clear-sky models, and the clear sky models performed poorly in removing the trend.…”

Section: Application and Discussionmentioning

confidence: 99%

A semiparametric spatio-temporal model for solar irradiance data

2016

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Design and operation of a utility scale photovoltaic (PV) power plant depends on accurate modeling of the power generated, which is highly correlated with aggregate solar irradiance on the plant's PV modules. At present, aggregate solar irradiance over the area of a typical PV power plant cannot be measured directly. Rather, irradiance measurements are typically available from a few, relatively small sensors and thus aggregate solar irradiance must be estimated from these data. As a step towards finding more accurate methods for estimating aggregate irradiance from avaialble measurements, we evaluate semiparametric spatio-temporal models for global horizontal irradiance. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple intepolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure.

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“…These shadows cannot be avoided because the distance between trackers cannot be too large due to wiring and land-use requirements. Moreover, back-tracking techniques [1] cannot be used in these kinds of plants as they are in conventional flat-plate photovoltaic tracking systems because HCPV modules must be always pointing to the sun. These shadows cause distortions in the electrical behavior of the system.…”

Section: Introductionmentioning

confidence: 98%

Shading in High-Concentrator Photovoltaic Power Plants

Rodrigo

Gutiérrez

Guerrero

2015

High Concentrator Photovoltaics

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The electrical behavior of high concentrator photovoltaic power plants is affected by self-shading between solar trackers. Partial shading of the concentrator modules on a tracker causes complex effects in the output I-V characteristics. Shadows affect the behavior of the basic component of a concentrator photovoltaic generator, the solar receiver integrated with primary optics, and the electrical connection of receivers with different behavior distortions the system output. In this chapter, measurements of concentrator receivers integrated with partially shaded primary optics are analyzed to understand their electrical behavior and a methodology for characterizing the I-V curve of shaded high concentrator photovoltaic generators under given environmental conditions is described and compared with experimental data. This methodology can be used for carrying out different studies on shading in high concentrator photovoltaic power plants. For instance, time domain simulations that calculate the I-V characteristic curve of a concentrator photovoltaic generator at small time steps can be implemented. These simulations can be used for calculating shading energy losses in grid-connected high concentrator photovoltaic systems or for analyzing important aspects in the design of these plants, such as optimum trackers allocation or inverters configuration. The problem of optimizing trackers allocation is also approached in this chapter with a simplified method based on balancing irradiation losses with energy losses in wires and costs of the land.

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Tracking and back‐tracking

Cited by 67 publications

References 7 publications

Parametric analysis and systems design of dynamic photovoltaic shading modules

Parametric analysis and systems design of dynamic photovoltaic shading modules

A semiparametric spatio-temporal model for solar irradiance data

Shading in High-Concentrator Photovoltaic Power Plants

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