PHYS Brown bag seminar: Towards maximum efficiency of colourful photovoltaics

Presenters: Janne Halme* and Pyry Mäkinen [New Energy Technologies (Renewable) group]

Abstract:

There has been recently increasing interest in developing colourful solar cells and modules for building- and product-integrated photovoltaics. In these applications aesthetics, in addition to efficiency and cost, is an important design factor. However, because the colour constitutes an optical loss from the perspective of solar energy conversion, a compromise between efficiency and aesthetics is required. To understand the interplay between solar cell colour and efficiency, we determined the theoretical efficiency limits of colourful single-band-gap solar cells [1]. The results show that a solar cell's colour is energy-wise optimally formed by reflecting all light within one or two distinct wavelength bands in the visible range, while passing the rest to an underlying solar cell. The results show that a broad range of brilliant colours are possible with more than 30 % theoretical efficiency, which represents less than 10 % relative performance loss compared to a completely black ideal solar cell. Our colour-efficiency -model allows us to evaluate the photovoltaic performance gains and losses associated with arbitrary, multi-coloured photovoltaic surfaces. Latest developments towards performance-optimized colourful photovoltaics for building- and product-integration will be discussed with practical examples from research and industry.

[1] Halme, Janne and Pyry Mäkinen. "Theoretical efficiency limits of ideal coloured opaque photovoltaics." Energy & Environmental Science (2019).

Join us for science and pizza in the Nanotalo lobby!