Photovoltaics can be attached to existing buildings or built into the fabric of new architecture. Integrating photovoltaics (PV) into building skins (building-integrated photovoltaics) provides the only feasible way of developing widespread use of PV in the UK. This is due to the substantial built-up areas in the UK, combined with diffuse sunlight that necessitates large areas of PV to generate useful amounts of electricity. In built-up areas, where power consumption is high, building exteriors are the main place in which photovoltaic arrays can be installed. The electricity generated by the PV can be used directly in the building or fed back into the grid. This gives the potential to reduce fossil fuel energy use in buildings, and so prevent further emissions of carbon dioxide that are so damaging to the global environment.
Building-integrated photovoltaics is a very significant area of development, as it leads to the possibility of making PV an integral part of the fabric of buildings, rather than an addition, by creation of new building materials that contain PV. Ensuring that these materials are also good insulators will reduce the energy consumption of the buildings in which they are used. The development of completely new building materials gives exciting possibilities for new architectural designs, allowing for artistic developments in building design at the same time as creating energy-efficient buildings.
Both new and existing buildings can benefit greatly from BIPV. The appearance of the building façade can be improved by the addition of different coloured PV cells and glazing containing PV. Figure 1 shows several ways in which PV can be used in a building, from wall mounting and glazing to installations on the roof. At the same time, PV can be used to blend in to the fabric of the building or to stand out, including creation of decorative elements.
Another important advance in this area is the development of luminescent solar concentrators (LSC’s). These are materials that concentrate light, so that PV that is used in conjunction with LSC’s can receive more light and so produce more electricity. Different coloured LSC’s are being developed, providing many possibilities for changing the appearance of buildings whilst enhancing their energy generation. Figure 2 shows the way in which BIPV is central to the development of energy-efficient buildings.
