Reshaping buildings to harness solar energy

Rooftop Photovoltaics (RTPV) is one of the most suitable applications of solar energy. RTPV can be installed quickly and requires no additional land. Its decentralised nature leads to reduction in congestion and losses in the distribution utility's network.

However, with the progress of technology and smarter architectural designs, solar energy can also be harnessed through other parts of a building, like facades, through Building Integrated Photovoltaics (BIPV). This has tremendous potential in India, especially considering that the country is yet to build 70% of its buildings.

RTPV uptake in India has been sluggish and achieving the 40 GW target for 2021-22 is likely to be a challenge. While there is a need for concerted efforts to enhance the growth of RTPV, it is important to realise that buildings are more than just roofs. A significant amount of sunlight falls on the remaining parts of the building as well. Thus, BIPV can play a crucial role in filling the gap left by RTPV.

BIPV is a technology that combines structural aesthetics with solar energy to develop eco-friendly architecture. It is designed after considering the electrical load and age of an existing building or, at the initial plan of a new structure, considering the type of construction materials, geographical location, orientation and existing RTPV policy (applicable to BIPV as well).

It replaces some of the traditional construction materials in portions of the roof, skylights or facades with solar photovoltaic materials to generate electricity. Since BIPV is similar to RTPV in terms of decentralised generation in buildings, the same policy can be applied, albeit with slight alterations.

While BIPV systems require higher investment, its capital costs are offset by the reduction in cost of other construction materials. For instance, when compared to glass, steel or other more conventional cladding materials, installing BIPV adds only a marginal extra cost (2-5%) to overall construction costs while significantly contributing to the energy supply in the building.

There are multiple BIPV products available in the market, catering to various needs. These include solar tiles for various parts of buildings, transparent glazing products for windows, light weight modules, solar shingles and weather resistant modules for roofs. Commercially, Tesla's solar shingles and Forward Lab's solar roofing products are the frontrunners when it comes to BIPV designs.

Globally, BIPV is picking up pace and receiving government support in many countries. Policies in Europe encourage conversion of buildings from energy consumers to energy producers through renewable energy adoption and retrofit actions. Germany, France and Italy offer incentives of 3.8, 9.57-18.7 and 3.1 -6.8 Rs/kWh of BIPV-based power generation, respectively.

Energy independence

BIPV can aid the Smart Cities Mission in energy management leading to net zero-energy smart buildings. By incorporating BIPV into construction, builders and real-estate developers can also improve their brand value and sustainability claims with certifications like Leadership in Energy and Environmental Design (LEED) and Building Research Establishment Environmental Assessment Method (BREEAM) ratings.

In Bengaluru, the IISc has an opaque type BIPV system installation of 5.25 kWp at the Centre for Sustainable Technologies. However, the beacon of BIPV in India is the SCOPE Minar office complex in Delhi. Enviro Energy Technologies commissioned a curved 100 kWp BIPV system covering the facade of this building. Interestingly, this installation used lesser area than a normal RTPV system would.

BIPV has the potential to increase energy independence at the level of individual buildings, while providing architects an opportunity to innovate in terms of aesthetics. Since the construction material itself generates electricity, it reduces the combined costs of both.

In order to meet the 40 GW RTPV target by 2021-22, the Ministry of New and Renewable Energy (MNRE) and state nodal agencies could seek inputs from industry stakeholders and the research community to help develop a robust BIPV policy including regulatory guidelines, business models and schemes.

While BIPV can create enormous employment potential, the requirement to train and build a skilled workforce will be a responsibility for the Skill Council on Green Jobs – an initiative launched by the Indian government and promoted by MNRE and Confederation of Indian Industry (CII).

Additionally, the solar manufacturing industry can focus on innovative products that integrate seamlessly with conventional and novel building construction technologies.

(Gajjar is research engineer and Ghosh is research scientist, CSTEP)