In the growing market for zero net energy buildings, Building integrated Photovoltaic (BIPV) products are increasingly sought by designers and clients to provide energy production whilst fulfilling a required function.
Whilst both function and appearance are essential for a positive result, striking the balance between the two (not to mention the 3rd factor of cost) can be difficult. A recent report from analysis firm NanoMarkets™ examines the different glass options currently available in the BIPV realm, detailing their respective merits and shortcomings. While the report, “BIPV Glass Markets–2014 and beyond“, states that BIPV glass will continue to become more common, it also notes the speed of its growth will depend on technological advances and the types of materials that are used.
Thanks to significant cost reductions and efficiency improvements in recent years, crystalline silicon (c-Si) is set to remain the most widely-used technology in BIPV applications despite its inherent disadvantages. These drawbacks include c-Si’s lack of transparency (making it a less-than-ideal choice for windows and skylights as it requires adjacent panes of ‘normal’ glass to allow light into its buildings), less desirable aesthetics, low level of versatility and relatively weak performance in diffuse light or partially-shaded conditions. Nevertheless, NanoMarkets™ anticipates that, whilst losing some market share, c-Si will continue to comprise at least 75% of the BIPV market through the end of the report’s study period.
The study does however; name a number of technologies that could be poised to make inroads into c-Si’s shrinking (but still dominant) market share. The most likely candidates include a range of thin-film PV technologies which have aesthetic and functional advantages over crystalline Silicon, although they are not yet as competitive on price and efficiency. The pros and cons of these technologies as described by NanoMarkets™ are summarised in the bullet points below.
- Copper Indium Gallium Selenide (CIGS): NanoMarkets™ notes that a number of the world’s remaining CIGS cell manufacturers–those who survived the turbulent period of oversupply that saw the demise of hundreds of solar cell producers globally–now specialise in BIPV. CIGS cells are well-suited to BIPV because of their physical flexibility, aesthetics, as well as their relatively high efficiency and good performance in diffuse light conditions.
- Cadmium-Telluride (CdTe): Although the only technology to surpass c-Si on cost-effectiveness for large-scale systems, “The CdTe market remains dominated by First Solar who hasn’t expressed interest in BIPV.” However, 3rd party manufacturers could & have used First Solar cells for BIPV applications. Because it is more flexible and better in diffuse conditions than c-Si, CdTe could be incorporated more easily into building substrates. Disadvantages include transparency and the toxicity of cadmium.
- Dye-Sensitised Solar Cells (DSC): DSC cells can be ‘printed’ onto or otherwise incorporated into glass substrates, and since their colour & transparency can be altered to achieve different aesthetic effects they are an ideal fit for BIPV applications. Furthermore, they perform well in diffuse light conditions. But prices remain high and overall efficiency low, meaning without further research, development and investment they are unlikely to disrupt the market anytime soon.
- Organic PV (OPV): While still in its early stages and not yet widely commercialised, OPV technology holds substantial promise. While their efficiency levels remain low compared to other technologies, OPV cells offer a number of environmental benefits. They contain no toxic materials and are essentially disposable or recyclable, ensuring their appeal for building projects where concerns about sustainability are tantamount.
- Amorphous Silicon (a-Si): The less-efficient but less-expensive cousin of crystalline silicon, a-Si has been used for decades in micro-scale solar applications such as calculators. Unlike c-Si, amorphous is flexible and performs better in diffuse sunlight. On the downside, a-Si efficiency levels still lag far behind those of c-Si. According to NanoMarkets™, one of the main reasons that a-Si remains viable for BIPV is the fact that many Chinese manufacturers remain in the market, “keeping it alive”.
The predicted growth in this segment over the next 8 years; from $800 million to around $4.6 billion, assumes advances in these technologies and improved pricing to provide ready products for net zero energy buildings, a much larger market than that currently using the BIPV glass products available.
Top photo: Thin-film solar panel in BIPV installation, via Wikipedia
© 2014 Solar Choice Pty Ltd
