Jakobsen, Michael Linde

Poulsen, Peter Behrensdorff

Rødder, Kristin

Rødder, Peter Melchior

Thorsteinsson, Sune

Bifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose a reflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, we investigate the impact of the reflector volume being filled with a refractive medium, and shows the refractive medium improves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel

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Ray Tracing Modelling of Reflector for Vertical Bifacial Panel - DTU Orbit (09/11/2017) Ray Tracing Modelling of Reflector for Vertical Bifacial PanelBifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose areflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, weinvestigate the impact of the reflector volume being filled with a refractive medium, and shows the refractive mediumimproves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel. General informationState: PublishedOrganisations: Department of Photonics Engineering, Optical Sensor Technology, Diode Lasers and LED Systems,SolarLab ApSAuthors: Jakobsen, M. L. (Intern), Thorsteinsson, S. (Intern), Poulsen, P. B. (Intern), Rødder, P. M. (Ekstern), Rødder, K.(Ekstern)Number of pages: 3Publication date: 2016 Host publication informationTitle of host publication: Proceedings of the 2016 European Photovoltaic Solar Energy Conference and Exhibition 2016ISBN (Electronic): 3-936338-41-8Main Research Area: Technical/natural sciencesConference: 32nd European Photovoltaic Solar Energy Conference and Exhibition, Munich, Germany, 20/06/2016 -20/06/2016Solar cells, Ray tracing, PV applications, Reflector, Energy systemsSource: PublicationPreSubmissionSource-ID: 124998415Publication: Research - peer-review › Article in proceedings – Annual report year: 2016 

Ray Tracing Modelling of Reflector for Vertical Bifacial Panel

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Downloaded from orbit.dtu.dk on: Nov 09, 2017Ray Tracing modelling of reflector for vertical bifacial panelJakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff; Rødder, Peter Melchior;Rødder, KristinPublication date:2016Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Jakobsen, M. L., Thorsteinsson, S., Poulsen, P. B., Rødder, P. M., & Rødder, K. (2016). Ray Tracing modellingof reflector for vertical bifacial panel. Poster session presented at 32nd European Photovoltaic Solar EnergyConference and Exhibition, Munich, Germany.Ray Tracing modelling of reflector for vertical bifacial panelM. L. Jacobsen1, S. Thorsteinsson1, P. B. Poulsen1*, P. M. Rødder2, K. Rødder2    1 Department of Photonics Engineering, Technical University of Denmark, Frederiksborgvej 399, Building 130, 4000 Roskilde, Denmark2 SolarLab, 8260 Viby J., Denmark* Contact: Phone +45 21325110; E-mail: ppou@fotonik.dtu.dkThis research is funded by the Danish Energy Agency within the EUDP programme with the project journal number  64014-0508 “SENSORPOWER – Bifacial PV Energy Reflector Tower”.Fig.1 (a). The bifacial solar cell and its two reflectors are illustrated in a 3D plot. The corresponding horizontal profile is illus-trated in (b). In (c) the three ray models, which are included in the model, are illus-trated. The three colors mark the same con-tributions in Fig.3. In (d) the experimental solar device is illustrated.MotivationBifacial solar cell modules can pro-vide a price advantage in production relative to normal solar cell modules if the effective light collecting area can become twice the area of a normal single-sided solar cell module of the same size. This can only be achieved by designing  an adequate reflector. Particularly, a design which is opti-mized for local winter conditions has our highest priority. We use ray-tracing models to opti-mize the interaction between the ver-tical bifacial solar cell module and vertical reflector designs and com-pare its performance with a almost reaches our ultimate goal of 2. single-sided PV-cell of same size. In case the bifacial PV cell could be un-folded the light collecting area and the power gain would be twice the reference. In this work, we investigate the impact of the reflector volume, being filled with a refractive medium, and shows that the relative power gain Fig. 3. The simulated relative irradiance the bifacial PV-cell and reflector when filled with acrylic (nr = 1.49), obtained on a summer day in CopenhagenThe modelThe vertical reflector consists of two mirrors mounted at ±45 deg. relative to the x-axis. The bifacial PV cell coincides with the x-axis, and all three components meet at x = L. As illustrated in Fig. 1a and Fig. 1b, the PV cell and the reflectors are surrounded by air with a refractive index of (na). The cavity between the mir-rors contains either air or a transparent medium with a refractive index of nr. The path of the incoming light is modelled by three ray paths, as it can be seen in Fig. 1c. Direct incidence of light onto the PV cell is modelled by the red line. Light re-flected once at the mirror and then incident onto the PV cell is modelled by the green line. Light reflected once at the mirror, and again at the entrance window/interface – if a medium is present  - is modelled by the blue line. These results include Fresnel losses at dielectric interfaces, material absorp-tion due to propagation in the dielectric medium and reflection at the mirrors. However, the sun model does not include diffuse light and we assume that the sun intensity is constant as long it is above the horizon.The resultsIn Fig. 2 and Fig. 3 the individual ray contributions are plotted as a func-tion of azimuth angle of the incoming light when air (nr = na) or acrylic (nr = 1.49) is present in the retroreflector, respectively. The blue line contrib-utes with zero power when air is present in the cavity.  For the reflection coefficient for the mirrors is set to 95%. The absorption coefficient for acrylic are set to 0.3 m-1. The table to the right lists the rela-tive power gains modelled at four lo-cations of different latitudes, and modelled for a day in the summer (23/6) and a day in the winter (21/12). The first numbers in the tables are for air between the mirrors, while the second numbers are for acrylic in be-tween the mirrors.  Software from Zemax is used for the ray trace modelling.  ConclusionAn optical raytracing model has been introduced to the bifacial PV-cell mounted inside a reflector. We demon-strate that relative to a single-sided PV cell of the same size we can obtain a relative power gain of at least 1.9 at any latitude with the bifacial PV design. OutlookThe model will be developed further in the near future, to include diffuse light, realistic sun data (see Fig.1d) and dif-ferent reflector configurations. LatitudeTrondheim (64°)Copenhagen (56°)Münich (48°)Rome (42°)Power GainDecemberair/acrylicPower GainJuneair/acrylic1.61 / 1.91 1.36 / 1.921.45 / 1.91 1.35 / 1.921.39 / 1.91 1.33 / 1.921.38 / 1.92 1.35 / 1.92a bdcAt Cph 23rd June    Ray 1    Ray 2    Ray 3    Total raysFig. 2. The simulated relative irradiance for one half of the bifacial PV-cell and reflector. (nr = na), obtained on a summer day in Copenhagen

Ray Tracing modelling of reflector for vertical bifacial panel

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Ray Tracing modelling of reflector for vertical bifacial panel

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