Digitally printed multicolored BIPV Stephen Wittkopf 1 Michaela

Digitally printed multi-colored BIPV Stephen Wittkopf 1) Michaela Terwilliger 2) Dirk Hengevoss 3) 1) 2) 3) PV Stele at Üserhuus headquarter, Hergiswil NW www. userhuus. ch www. hslu. ch www. fhnw. ch wittkopf 4 userhuus@gmail. com michaela. terwilliger@hslu. ch dirk. hengevoss@fhnw. ch

Agenda Introduction Design project PV Stelen Environmental assessment Testing and certification Conclusion and acknowledgements

Scope – why multi-coloured PV modules? Challenge Swiss energy strategy 2050 aim to increase national electricity supply from PVs from 2% (2016) to 20% (2050) Approach: Building integrated photovoltaics (BIVP) § utilising building surfaces, such as roof and façade § technically and economically viable § increase acceptance with aesthetically pleasing, multicoloured glass-glass PV modules § drawback: reduction in efficiency

Layer composition of printed PV module § translucent multi-coloured print § printed on the inner surface of the front glass sheet

Design project – PV Steles • 6 digital ceramic printed and laminated glass-glass modules size 230 x 55 cm • Satinated glass 4 mm, no reflection to the surrounding • Laminated with monocristallin, active wire cells, 42 cells each module • Earth tone colors with RE 75 • Motiv 3 greek goddesses and 3 greek pillars • Metall construction on concrete foundation

Design project – PV Steles Layout plan

Design project – PV Steles Monitoring

Design project – PV Steles • Color pick of subdued tones • Selected pantone halftone colors which are most likely possible for aesthetic appeal in building facades • Different colors = different print opacities for the same result of electric efficiency • Effiency loss tested trough csem neuchatel assessed with EQE measurements • Satinated glass as an alternative to reduce potentional glare effects Satinated glass Float glass

Design project – PV Steles Quality check of the laminated modules 20 pl 40 pl 10 pl

Eco-points of the production of 60 -cell module Backsheet foil Others Electric connections Printing Solar glass Solar cell Figure: Park at al § share eco-points of solar cells 65 -80% § impact m-Si < impact s-Si § impact of printing neglectable

Eco-point share of 140 PV module façade m-Si MCGG façade 25 k. Wp s-Si MCGG façade 28 k. Wp Figure: Park at al § The solar cells contribute most to the total eco-points of BIPV façades § If an existing rain cladding will be replaced, the impact of the solar glass, mounting system and transport (~20%) can be allocated to the building.

GWP of 1 k. Wh generated at PV façade § GWP impact of most configurations ≤ European reference § GWP impact of most configurations > Swiss reference European low voltage electricity grid Swiss low voltage electricity grid as reference Swiss low voltage electricity grid* Figure: Park at al *Swiss electricity production mainly by hydro and nuclear power

Energy Pay Back Time (EPBT) non-renewable Energy § EPBT non-renewable Energy at south and east/west orientation of m-si PV façade at 18% - 35% of total lifetime (30 yr). Figure: Park at al

Summary of environmental assessment • The environmental impact of printing is negligible. • The PV cells making > 40% of total impact of a MCGG silicon PV façade, the solar glass < 10%. • More resource efficient cell production or an increase of solar cell efficiency have the most positive effect to reduce the eco-points of the generated electricity. • From the environmental perspective, s-Si cells are not suitable in general cases. The higher efficiency does not compensate the higher eco-points of production.

IEC Compliance Design specification: HSLU Glas printing/supply: Glas Trösch PV Module production: GES IEC specification: SUPSI Testing/Certification: Kiwa Licence holder: Üserhuus

IEC Compliance

Further reading https: //www. hslu. ch/en/lucerne-university-of-applied-sciences-and-arts/aboutus/people-finder/profile/? pid=1797

Conclusion and acknowledgements Acknowledgements: University of Applied Sciences and Arts, Swiss National Science Foundation, Innosuisse, Glas Trösch, GES, Gemperle Digitally printed PV modules: • Do not add environmental burden • Are safety and performance tested and certified • Facilitate design diversity for improved visual integration