The demand for renewable energy is rising faster than sources can supply it, especially in major urban areas. The glass skyscrapers associated with the wealth of developed nations have become serious energy drains, requiring more electricity to keep them cool as the windows turn them into giant greenhouses. One potential solution is the use of integrated photovoltaics, taking advantage of the large surface area of these buildings. But, what’s the best way to deploy this technology?
BIPV refers to building integrated photovoltaics, meaning that photovoltaic materials were used in the construction of the building from the start. They mitigate a higher cost by reducing the need for other materials. BAPV is slightly different, standing for building applied photovoltaics. This is usually used in regards to photovoltaic materials added to an existing building through a retrofit.
For the most part, BIPV was installed in buildings that were further away from the electrical grid and required an auxiliary source of energy. In recent years, photovoltaics have been fitted to the roofs of buildings, mostly in the form of individual solar panels or tiles. However, this may be changing. Writing on behalf of BRE’s National Solar Centre, Steve Pester explains:
“At present the market for BIPV is quite limited. On domestic buildings, BIPV tends to be restricted to a few roof tile products that are sometimes used on new build developments. There is a market at the opposite end of the scale, with special (and expensive) façades or overhead glazing being used on large public or commercial buildings. But at the NSC we passionately believe that in the future BIPV will be a widespread and ordinary part of the building process – it is just a question of how quickly we can make it happen.”
One reason that BIPV is being incorporated into more building designs is that architects have more raw material available to them. A glut of solar grade silicon has meant a dramatic drop in the price of photovoltaic panels and the abundance has led to more versatile forms of the technology. Photovoltaics are increasingly available in different colours, styles and textures, meaning they can be used in a design more easily.
Although photovoltaics are still expensive enough to give designers pause, it’s posited that their widening usage will go a long way to achieving the zero energy building (ZEB) target set by the EU by 2020. Amongst other challenges will be the need to take a scientific view of energy yields, architectural constraints, and economic feasibility. Much is dependent on location.
BAPV usage is likely to increase with the advances in photovoltaic ‘film’ coatings that can be applied to existing surfaces, including windows. Some transparency is currently still lost, but the films are becoming more and more transparent over time. It is not fantasy to imagine that eventually they will be almost invisible, and come with extraordinary ease of application. Today’s models are hindered by weatherability issues, making their replacement too frequent in some locations to be financially viable. But the situation on the ground is changing each year.