With the development of curtain wall technologies following the Industrial Revolution, glass has evolved from being a minor building envelope material – essentially for doors and windows only – to representing a stand-alone type of architectural skin, totally transforming visual communication between the inside and the outside of buildings as well as their energy performance. If curtain walls allow the passive use of solar energy in buildings, on the other hand they require the installation of screens to regulate the solar gain and to prevent dazzle. Such screens can be even integrated into the glass panels, in products like coloured or digitally printed glass. Despite the advanced manufacturing technologies available today, coloured glass is not a recent architectural solution, as stained glass has found application for centuries in church windows, where it was also a medium used to tell religious stories and educate believers of all cultural levels.
What if coloured glass screens could also produce clean, free energy to power buildings? This possibility has already been explored for instance by the American artist Sarah Hall, who has combined solar cells with stained glass for architectural façades.
The Spanish company Onyx Solar provides high quality photovoltaic glass suitable for a variety of architectural applications. In fact, they develop building integrated photovoltaic solutions that can be used to replace conventional cladding materials from different parts of the building envelope – such as skylights, façades, windows, curtain walls and roofs – in order to generate electricity from sunlight while filtering out the harmful radiation and providing both thermal and sound insulation at the same time.
In contrast to traditional solar panels, photovoltaic glass can be beautifully integrated into architectural envelopes with a high level of customisation, for which Onyx Solar provides infinite combinations of photovoltaic glass: you can choose your colour, pattern, transparency degree, thickness and size.
Unlike other solar panels manufacturers, Onyx Solar is also a specialised design firm, offering a range of services adapted to any client’s needs. Having their in-house architects and engineers, they can provide support in the analysis and design of complex architectural envelopes that present, for example, panels of different shapes, sizes, orientation and tilt.
Onyx Solar offers photovoltaic glass with either crystalline silicon cells or amorphous silicon. Both types of products are expected to last for 25 years, to be then dismissed like conventional laminated glass. Photovoltaic glass with integrated thin film solar panels looks more aesthetically pleasant, although it is generally less efficient than crystalline silicon except when the sky is cloudy. What makes the panels coloured is a PVB foil inserted between the glass panes, on the inside in order not to cover the active silicon layer applied in patterns. These can vary and provide different transparency degrees.
Despite its beauty and the variety of possible applications, photovoltaic glass still has some limitations: for instance, it is not ideal for doubly curved architectural surfaces, as curved solar glass panels present problems. In fact, developing curved photovoltaic glass is one of the research focuses at Onyx Solar. The company is also involved in numerous research programmes: for example, they have contributed as technology providers to the European Project R2CITIES, aiming to develop an open and easily replicable strategy for achieving nearly zero energy cities. Onyx Solar has even had a leading role in ARTESUN, another European research project to make Organic Photovoltaic Technology (OPV) more efficient, stable and cost effective. Additionally, in collaboration with University of Valladolid, Onyx Solar has worked on the development of dyed sensitised solar cells with the aim to make a photovoltaic paint for architectural applications.
Among the solar glass products offered by Onyx Solar there is even a coloured PV walkable anti-slip floor, a solution which is already available in the market. In conclusion, it seems that visually stimulating solar energy plants could hypothetically replace many conventional architectural surfaces exposed to sunlight.