Details
| Original language | English |
|---|---|
| Pages (from-to) | 495-503 |
| Number of pages | 9 |
| Journal | Energy Procedia |
| Volume | 124 |
| Publication status | Published - 21 Sept 2017 |
| Event | 7th International Conference on Silicon Photovoltaics, SiliconPV 2017 - Freiburg, Germany Duration: 3 Apr 2017 → 5 Apr 2017 |
Abstract
We evaluate the optical performance of PV modules with respect to an increase in short circuit current density. Our evaluation is based on the combination of ray tracing simulations and measurements on test modules with four types of backsheets: Two of them are structured, the third is white and diffusively reflecting and the fourth reflects no light. Under normal incidence, structured backsheets reflect incoming light at an angle that causes total internal reflection at the glass/air interface, which guides the light to the solar cell surface. Three different irradiance conditions are studied: a) standard testing conditions (STC) with light incident perpendicular to the module surface, b) variation in the angle of incidence and c) light source with mean annual distribution of angles of incidence. Using the measured refractive index data in ray tracing simulations we find a short circuit current density (Jsc) gain of up to 0.9 mA/cm2 (2.3%) for monofacial cells and a structured backsheet, when compared to a white backsheet with diffuse reflection. For bifacial cells we calculate an even larger Jsc increase of 1.4 mA/cm2 (3.6%). The Jsc increase is larger for bifacial cells, since some light is transmitted through the cells and thus more light interacts with the backsheet. Our optical loss analysis reveals the best performance in STC for edge-aligned Ag grooves. This structure reduces absorption losses from 1.8 mA/cm2 to 0.3 mA/cm and reflection losses from 0.7 mA/cm to 0 mA/cm. This trend also holds under various angles of incidence as confirmed consistently by Jsc measurements and ray racing simulations. Simulations using an annual light source emitting a mean annual distribution of angles of incidence reveal grooves in both orientations edge alignment and east-west alignment achieve similar current gains of up to 1.5% for mono- and of 2.5% for bifacial cells compared to modules with white back sheets. This indicates that for modules with light guiding structures such as these backsheets optimization for STC differs from optimization for annul yield.
Keywords
- Backsheet, bifacial cells, cell spacing area, light harvesting, light recovery probability, optical loss analysis, PV modules
ASJC Scopus subject areas
- Energy(all)
- General Energy
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In: Energy Procedia, Vol. 124, 21.09.2017, p. 495-503.
Research output: Contribution to journal › Conference article › Research › peer review
}
TY - JOUR
T1 - PV module current gains due to structured backsheets
AU - Vogt, Malte R.
AU - Holst, Hendrik
AU - Schulte-Huxel, Henning
AU - Blankemeyer, Susanne
AU - Witteck, Robert
AU - Bujard, Patrice
AU - Kues, Jan Bernd
AU - Schinke, Carsten
AU - Bothe, Karsten
AU - Köntges, Marc
AU - Brendel, Rolf
N1 - Funding Information: This work was supported by the German Federal Ministry for Economic Affairs and Energy through the “PERC2Module” project under Contract 0325641. We would also like to thank Sarah Spätlich, Ulrike Sonntag, Till Brendemühl for the cell production. Publisher Copyright: © 2017 The Authors. Published by Elsevier Ltd. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/9/21
Y1 - 2017/9/21
N2 - We evaluate the optical performance of PV modules with respect to an increase in short circuit current density. Our evaluation is based on the combination of ray tracing simulations and measurements on test modules with four types of backsheets: Two of them are structured, the third is white and diffusively reflecting and the fourth reflects no light. Under normal incidence, structured backsheets reflect incoming light at an angle that causes total internal reflection at the glass/air interface, which guides the light to the solar cell surface. Three different irradiance conditions are studied: a) standard testing conditions (STC) with light incident perpendicular to the module surface, b) variation in the angle of incidence and c) light source with mean annual distribution of angles of incidence. Using the measured refractive index data in ray tracing simulations we find a short circuit current density (Jsc) gain of up to 0.9 mA/cm2 (2.3%) for monofacial cells and a structured backsheet, when compared to a white backsheet with diffuse reflection. For bifacial cells we calculate an even larger Jsc increase of 1.4 mA/cm2 (3.6%). The Jsc increase is larger for bifacial cells, since some light is transmitted through the cells and thus more light interacts with the backsheet. Our optical loss analysis reveals the best performance in STC for edge-aligned Ag grooves. This structure reduces absorption losses from 1.8 mA/cm2 to 0.3 mA/cm and reflection losses from 0.7 mA/cm to 0 mA/cm. This trend also holds under various angles of incidence as confirmed consistently by Jsc measurements and ray racing simulations. Simulations using an annual light source emitting a mean annual distribution of angles of incidence reveal grooves in both orientations edge alignment and east-west alignment achieve similar current gains of up to 1.5% for mono- and of 2.5% for bifacial cells compared to modules with white back sheets. This indicates that for modules with light guiding structures such as these backsheets optimization for STC differs from optimization for annul yield.
AB - We evaluate the optical performance of PV modules with respect to an increase in short circuit current density. Our evaluation is based on the combination of ray tracing simulations and measurements on test modules with four types of backsheets: Two of them are structured, the third is white and diffusively reflecting and the fourth reflects no light. Under normal incidence, structured backsheets reflect incoming light at an angle that causes total internal reflection at the glass/air interface, which guides the light to the solar cell surface. Three different irradiance conditions are studied: a) standard testing conditions (STC) with light incident perpendicular to the module surface, b) variation in the angle of incidence and c) light source with mean annual distribution of angles of incidence. Using the measured refractive index data in ray tracing simulations we find a short circuit current density (Jsc) gain of up to 0.9 mA/cm2 (2.3%) for monofacial cells and a structured backsheet, when compared to a white backsheet with diffuse reflection. For bifacial cells we calculate an even larger Jsc increase of 1.4 mA/cm2 (3.6%). The Jsc increase is larger for bifacial cells, since some light is transmitted through the cells and thus more light interacts with the backsheet. Our optical loss analysis reveals the best performance in STC for edge-aligned Ag grooves. This structure reduces absorption losses from 1.8 mA/cm2 to 0.3 mA/cm and reflection losses from 0.7 mA/cm to 0 mA/cm. This trend also holds under various angles of incidence as confirmed consistently by Jsc measurements and ray racing simulations. Simulations using an annual light source emitting a mean annual distribution of angles of incidence reveal grooves in both orientations edge alignment and east-west alignment achieve similar current gains of up to 1.5% for mono- and of 2.5% for bifacial cells compared to modules with white back sheets. This indicates that for modules with light guiding structures such as these backsheets optimization for STC differs from optimization for annul yield.
KW - Backsheet
KW - bifacial cells
KW - cell spacing area
KW - light harvesting
KW - light recovery probability
KW - optical loss analysis
KW - PV modules
UR - http://www.scopus.com/inward/record.url?scp=85031937543&partnerID=8YFLogxK
U2 - 10.1016/j.egypro.2017.09.286
DO - 10.1016/j.egypro.2017.09.286
M3 - Conference article
AN - SCOPUS:85031937543
VL - 124
SP - 495
EP - 503
JO - Energy Procedia
JF - Energy Procedia
SN - 1876-6102
T2 - 7th International Conference on Silicon Photovoltaics, SiliconPV 2017
Y2 - 3 April 2017 through 5 April 2017
ER -