The new guidelines on improving energy efficiency set out by the European Commission are forcing EU countries to transform their energy generation system with an increasing focus on renewable energies. In this context, the development of photovoltaic technologies that can be easily integrated into urban applications can play a decisive role in the coming years.

The aim of the project was to overcome the barrier of the aesthetic impact of photovoltaic elements on urban façades, as they are opaque and normally black or grey devices, replacing them with ceramic pieces that develop photovoltaic capacity in the surface finish layers without altering the properties of any ceramic piece of façade or roof.

The project, led by KERABEN GRUPO, has also involved eight other companies from different sectors and distributed throughout Spain: Aliter Grup Renovables, Cerámica la Escandella, Ecopol Tech, Ingeniería Navarra Mecánica, Obras y Servicios Tex, Kerafrit and Lenz Instruments. In addition, four research centres have collaborated in the project: Centro Tecnológico Lurederra, Universitat Jaume I (UJI), Fundació Institut de Recerca en Energia de Catalunya (IREC) and Universitat Politècnica de Catalunya (UPC).

The FOTO-CER project has been subsidised by the Centre for Technological Development and Innovation CDTI within the MISSIONS Programme.

On a laboratory scale, a functional photovoltaic cell on ceramic has been achieved, meeting the objectives of functionality, aesthetics and durability.

Functionality refers to the efficiency of light utilisation taking into account the photovoltaic conversion efficiency and transmission (TP) in the visible spectrum (400-750 nm). The developed parts exceed a TP>0.5 transmission, which ensures the development of efficient photovoltaic solutions that are compatible with their integration into the entire façade and, therefore, contribute to increasing energy production and management in buildings. On the other hand, aesthetics has been assessed through the colour rendering index CRI, which provides information on the transparency of the layers to ensure the absence of colouring effects that may affect the aesthetic appearance of the ceramic substrates. CRI values of 60 have been exceeded, which guarantees that the photovoltaic device developed that complies with it will be practically invisible to the human eye, meeting the desired aesthetic requirements. Finally, it has been possible to validate the durability of the photovoltaic coatings after subjecting the developed samples to particularly aggressive accelerated ageing cycles, simulating outdoor exposure for a service time of at least 20 years.

The next step would be to scale up the different processes involved in the manufacture of such a photovoltaic cell so that the product could reach the market to cover specific demand niches.

More information available in FOTO-CER.

Ceramic with PV cell coating

Comparison of transparency between two VF cells: yellowish (top) transparent (bottom)