BIPV (building-integrated photovoltaics) technically refers to the concept of incorporating multifunctional building elements to the building envelope to generate electricity. This emerging sector in the solar PV market has been showcasing significant growth across the globe in recent years, thus paving the way for a more sustainable future. Furthermore, the recent technological advancements in the BIPV segment enhanced the architectural aesthetic expression of the building by replacing the age-old conventional building elements. Moreover, the technological shift of PV into the architectural field led to innovative design approaches and several unscathed challenges. However, the BIPV industry has made a commendable achievement by providing a plethora of products with additional features like multi-functionality, mass customization, and cost-effectiveness for attractive building applications. It is worth to mention that apart from construction and functional aspects, BIPV at present is one of the many cornerstones for contemporary innovation in the field of architecture . The basic idea behindhand integrating PV modules onto a building surface is to replace the conventional construction parts such as roof, façade, or skylight with multifunctional photovoltaic materials that can convert solar energy into electricity. Eventually, the construction of new buildings can favor BIPV as their major source of electrical power, whereas, the existing buildings can be retrofitted with BIPV modules as well.
The rapid growth of BIPV systems in the photovoltaic industry accounts to some key features ,
- Substantial cost reduction, both in terms of constructional materials as well as labour cost.
- Multifunctional BIPV applications promote material and electricity cost savings.
- Enhances the architectural elegance of existing as well as new buildings
- Significantly reduces the electricity transmission losses.
- Technological advancements make use of innovative materials for economically feasible BIPV modules.
- Highly customizable with the various size and colour options available in the market.
- BIPV incorporations can ensure a significant reduction in the energy payback period (EPBT).
The categorization of the BIPV system can be made according to the PV technology used, application type, and finally based on the available market names.
At present, the PV technologies available in the market can be classified into 3 distinct generations namely the 1st, 2nd, and 3rd generation PV technologies. The first generation opaque type PV modules are composed of either monocrystalline or polycrystalline silicon structures with an average thickness between 0.2 to 0.5 mm . Distinctively, the second generation PV modules span the semi-transparent and transparent thin-film technology. Materials like Amorphous silicon, Copper-Indium-Gallium (CIGS), Copper-Indium-Selenide (CIS), and Cadmium-Telluride (CdTe) make up the second-generation thin films owing to its better flexibility and a much lower average thickness . Similar to the 2nd generation PV technology, flexible thin-film technology is adopted in the 3rd generation category. Relatively high flexibility, tunable transparency, and availability of customizable colour options are a few added advantages of this upcoming technology. DSSC an acronym for dye-sensitized solar cell is one example of third-generation technology that can generate electricity even under partial lighting conditions .
It is also interesting to note that despite their lower efficiency range as compared to the 1st generation crystalline silicon cells, the thin-film technology had gained market interest in recent years mainly due to its economically viable fabrication technique as well as the fact that they are highly customizable. However, even though the 3rd generation technology incorporates a more feasible production technique, factors like material toxicity and stability hold to be an opposing factor in its mass publicity.
An increase in energy requirements of buildings favored the growth of PV application in façade segments. Moreover, the use of semi-transparent BIPV modules on building façade helps to regulate the indoor microclimate and enhance comfort levels by relying on natural lighting. Solar façades are considered to be a great solution for energy generation with several other salient features including façade insulation, additional thermal properties, noise reduction as well as balcony glazing. Furthermore, solar façade modules can also be integrated into existing building facades, modernizing them, and turning them energy efficient. Façade integrated systems are further classified into curtain wall products, solar glazing, and spandrel panels.
Curtain wall products are generally BIPV façade modules that balance daylighting, and shading occurrences. A curtain wall can achieve all the building envelope requirements such as thermal and noise insulations, weather-proofing as well as load-bearing. It also adds to the thermal and visual comfort of the building. Rain screen façade (cold façade) also comes under this category where the air gap between the cladding and the sub-frame facilitates cooling effect and thereby improving the efficiency of the module.
Crystalline silicon with adjusted spacing or semi-transparent thin-film PV modules sandwiched between glass panels provides filtered vision and acts as solar glazing and allows daylight inside the buildings. They can also be used as a skylight. These panels are generally glass-glass laminates with tunable light transmission capabilities. Skylights or solar glazing can be integrated onto pitched, flat, or even curved roofs.
Spandrel panels are pre-assembled opaque glass laminates integrated with any curtain wall system. Opacity is the significant parameter of any spandrel panels. Opaque glass translates to higher solar cell density and eventually higher energy yield. With cutting-edge technology, a wide range of customizable options are available in this segment. Moreover, junction boxes and other wiring components are easily hidden behind the glass panel owing to enhanced aesthetic solutions
Identical to above applications, features like roof size, ease of installation, and inclined orientation towards the sun make BIPV roof applications as significant as any other technologies. The last few years had witnessed a tremendous increase in the development of many constructive solutions, moving from 1st generation PV technology (mostly used with building attached photovoltaics BAPV) towards the current state of the art watertight solar tiles and shingles, where the PV modules replace the conventional roof tiles. The roof-integrated PV systems can be further subcategorized into solar shingles, tiles, standing seam roofing products, and also skylights.
Solar shingles, also known as PV shingles corresponds to continuous opaque BIPV modules integrated onto the roof. They possess similar flexibility and durability as regular asphalt shingles. Solar shingles are made up of thin-film technology using CIGS material. The aesthetically appealing and sleek design has elevated its market popularity. Even though they are still growing in popularity, solar shingles are less efficient as compared to regular solar panels.
On the other hand, solar tiles are roof-integrated BIPV modules identical to conventional roof tiles. They are installed at geometrically defined places on the roof near the conventional tiles. Moreover, solar tiles uphold both the functional and aesthetic aspects of BIPV. Furthermore, uniformity in design can be achieved after integrating solar tiles on rooftops.
The skylight roof application consists of semi-transparent BIPV module installations capable of generating free and clean energy. Besides, they also provide additional energy savings due to the enhanced thermal insulation properties and also controls the solar radiation by absorbing almost all the infrared and ultraviolet rays. The advantages mentioned above help in a significant reduction in the carbon footprint of the building. Moreover, solar skylight facilitates a boost in the thermal performance of the building interior.
Innovative state of the art technologies like Smart Wire Connection Technology (SWCT) is one among the several upcoming trends. SWCT is a breakthrough connecting technology compatible with almost all the cell technologies available in the market. Not to mention the key features like long term cell durability, and enhanced cell efficiency as compared to ribbon-based cell connectors. Moreover, SWCT opens the door to a broader range of applications on account of its bonding works with a variety of semiconductors and other metals.
Distinctively, the Metal Wrap through (MWT) technology is yet another innovative and efficient update in BIPV Segment. In MWT, the electrical energy channelling metal layer will be located behind the cells via metal-coated holes or vias in the cell. Thus, the effective PV area can be maximized along the building to maximize energy efficiency.
With vast technological advancements, BIPV arena witnesses an ever-increasing PV module efficiency along with substantial drop in module prices. Thus, in a nutshell, exponential growth can be observed in the PV market especially within the BIPV segment where numerous customizable options are available both with the PV module size as well as colour options. The innovation of customized colour without compromising the energy conversion efficiency is likely to open a new era of sustainable design. Aesthetics has also been one of the major issues in the commercialization of BIPV products. This points out that, BIPV market would be among the global mainstream markets shortly. It is important to note that, the significant adoption of environmentally friendly energy sources by MNCs to limit carbon
footprints and also the growing subsidies and tax reduction offered by the government bodies has bolstered the demand for the products. Besides, the demand for the product has stemmed from the increased adoption of integrated roofs, windows, and facades owing to its enhanced aesthetic characteristics. Moreover, incorporation of state of art R&D facility is paving the way for innovative and efficient technology has also favoured the BIPV market growth.
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