Efficiency of silicon thin-film photovoltaic modules with a front coloured glass

Photovoltaic electricity has already proven its ability to compete with other well established technologies for energy production. The abundant and non-toxic raw materials, the yearly increasing efficiency as well as the production cost of silicon thin-film solar cells getting lower and lower make this technology always more interesting for a wide spread use. Beside the functional features, the size, colour and glass texture of a PV module determine its appearance and aesthetics. In order to be more compliant with the built environment, photovoltaic installations have to be improved in terms of visual rendering, matching of colour of the existing roof-tops and parasitic reflections. The crystalline technology already offers various types of systems with a large choice of shapes, textures and colours as well as “semi-transparent” modules more easily integrated in the roof-tops or facade. By changing the anti-reflective coating (ARC) of a crystalline solar cell, it is possible to modify their colour [1]. However, for thin-film silicon technology the challenge is completely different, and up to now, the only way to modify the module colour is to reduce the thickness of the active layer and consequently its efficiency. Therefore new ways to enhance the visual rendering of the thin-film modules have to be explored. A study led in the frame of the ArchinSolar project [2] has shown that architects are ready to integrate PV modules with enhanced aesthetic aspect, even though there was a 10 % loss in efficiency. The present study shows how new coloured filters can be used to enhance PV modules’ appearance while minimizing power loss, to achieve a better integration in the traditional urban or rural environment.