TY - JOUR

T1 - Measuring the light recovery factor of backsheets in photovoltaic modules

AU - Köntges, Marc

AU - Schulte-Huxel, Henning

AU - Blankemeyer, Susanne

AU - Vogt, Malte R.

AU - Holst, Hendrik

AU - Reineke-Koch, Rolf

N1 - Funding information: We gratefully acknowledge the financial support by the German Federal Ministry for Economic Affairs and Energy under FKZ 0325641 (PERC-2-Module) and by the State of Lower Saxony. We gratefully acknowledge the financial support by the German Federal Ministry for Economic Affairs and Energy under FKZ 0325641 (PERC-2-Module) and by the State of Lower Saxony .

PY - 2018/11

Y1 - 2018/11

N2 - We measure the short circuit current improvement of various commercial backsheets for passivated emitter and rear solar cells (PERC) in photovoltaic (PV) modules. We quantify this improvement by a light recovery factor k defined as the share of the light reflected by the backsheet around the cell in a PV module laminate, which is converted into electrical current by the solar cells in the module relative to a reference rear surface. The presented measurement method allows measuring the light recovery factor as function of the incident light beam angle, which are important for the calculation of the yield analysis in the field. Simulations of the recovery factor with the optical ray tracing program DIADALOS are performed in order to support the interpretation of the results. For measuring the absolute light recovery probability of a backsheet one should use a reference backsheet with an absorbance of close to 100% to avoid systematic reflection errors especially for high incident light beam angles > 50°. The ranking of various recovery factors are compared to the ranking measured by reflectance measurements defined in standard IEC 62788-2 Ed.1 for backsheets. The standard shows a substantial deviation between the ranking of recovery factor and the reflectance which can be corrected by using an adapted definition for the reflectance measurement method.

AB - We measure the short circuit current improvement of various commercial backsheets for passivated emitter and rear solar cells (PERC) in photovoltaic (PV) modules. We quantify this improvement by a light recovery factor k defined as the share of the light reflected by the backsheet around the cell in a PV module laminate, which is converted into electrical current by the solar cells in the module relative to a reference rear surface. The presented measurement method allows measuring the light recovery factor as function of the incident light beam angle, which are important for the calculation of the yield analysis in the field. Simulations of the recovery factor with the optical ray tracing program DIADALOS are performed in order to support the interpretation of the results. For measuring the absolute light recovery probability of a backsheet one should use a reference backsheet with an absorbance of close to 100% to avoid systematic reflection errors especially for high incident light beam angles > 50°. The ranking of various recovery factors are compared to the ranking measured by reflectance measurements defined in standard IEC 62788-2 Ed.1 for backsheets. The standard shows a substantial deviation between the ranking of recovery factor and the reflectance which can be corrected by using an adapted definition for the reflectance measurement method.

KW - Backsheet

KW - Light harvesting

KW - Light trapping

KW - Module efficiency

KW - PV module

UR - http://www.scopus.com/inward/record.url?scp=85049324536&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2018.06.028

DO - 10.1016/j.solmat.2018.06.028

M3 - Article

AN - SCOPUS:85049324536

VL - 186

SP - 175

EP - 183

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

ER -