Photovoltaic glaze for buildings has been around for many years. However, this technology is yet to become widely known and used. This article sheds light on this innovative solution for sustainable buildings.
Photovoltaic cells explained
Photovoltaic cells (PV), or simply solar cells, directly transform sunlight into electricity. They are quite different from solar thermal panels, which use the sun’s heat to produce hot water. Traditionally, photovoltaic cells were approximately 150mm square and could produce up to 5 volts. This meant that in order to generate a higher voltage, one would need many PV cells forming a panel, and many panels forming an array. New technologies, such as a printing press using solar dyes, are improving how PV cells can be used, including construction applications.
With an industry-wide calling for sustainable infrastructure, PV cells can definitely be a game-changer. In fact, the carbon footprint associated with manufacturing photovoltaic has halved in the past decade. Performance improvements, raw material savings and process improvements are the main causes of the reduction in emissions. The most widely-used type of photovoltaic cells is the crystalline PV, which has a typical efficiency of around 13-15%. This translates to around 100kWh per square metre per year in the UK.
BIPV – the future of photovoltaic systems?
In an attempt to minimise the materials used in buildings, traditional PV systems have developed into building-integrated photovoltaics (BIPV). These are photovoltaic materials that can be used in different areas of a building. The applications vary from roofs and facades to curtain walls and glazed stairwells. Back in 2016, London saw its first transparent solar bus shelter. Polysolar, a company specialised in PV systems, installed its transparent photovoltaic glazing in a smart bus shelter at Canary Wharf. The photovoltaic glazing is able to generate electricity even in low and ambient light. Capable of producing 2,000kWh per year, it could power an average home in London. The energy helped power smart signage on the state.
Landmark buildings that you may be surprised to know are using photovoltaic glaze
King’s Cross railway station is another good example of the photovoltaic glaze’s applications. The roofing, renewed in 2014, has glass-glass BIPV laminates, making it transparent. Also, the renovation of the Appleton Tower at Edinburgh University included 80 solar photovoltaic modules attached to the building.
A more emblematic example comes from the 230m high Heron Tower in London. It was completed in 2011 and has 153kWp of glass-glass laminates built into the south elevation of curtain walling from street level to the top of the tower. The southern facade, therefore, helps the building to minimise its environmental footprint by generating electricity from its windows.
The cost misconception of photovoltaic glaze and BIPV
Although there seems to be clear advantages in the use of photovoltaic glaze in buildings, the technology has yet to become mainstream despite the clear advantages and decreased costs in recent years. With buildings in the EU being responsible for 40% of the energy consumption and around 36% of greenhouse gas emissions, photovoltaic glaze could play a critical role in improving sustainability. But the truth is that there is a common misconception about the cost of photovoltaic cells and BIPV.
One of the main advantages of BIPV is that from an aesthetic point of view, it looks like part of the building, rather than a bolt-on. But beyond the aesthetic advantage, there is an often overlooked cost efficiency. When BIPV, such as photovoltaic glaze, is used in a building, it replaces part of the materials that would have been needed otherwise. So it is a 2-in-1 solution. Rather than purchasing glass windows beside photovoltaic cells, it is sufficient to buy the photovoltaic glaze, which will not only generate electricity but also serve as windows. Therefore, BIPV systems offset the cost of traditional buildings.
Although it is true that some innovative products such as solar tiles are still too costly to be widely implemented, other photovoltaic glazings can be cost-effective nowadays. With buildings regulations being ever tighter with regards to sustainability, it is only a matter of time before photovoltaic glazing becomes the norm. We are ready for the change.
How about you? What do you think about photovoltaic glazing? Will it be the turning point for buildings’ sustainability? Let us know in the comments below!