The photovoltaic (PV) system is one of the most promising technologies that generate benevolent electricity. Therefore, fossil fuel-generated electric power plants, that emit an enormous amount of greenhouse gases, can be replaced by the PV power plant. However, due to its lower efficiency than a traditional power plant, and to generate equal amount of power, a large land area is required for the PV power plant. Also, transmission and distribution losses are intricate issues for PV power plants. Therefore, the inclusion of PV into a building is one of the holistic approaches which reduce the necessity for such large land areas. Building-integrated and building attached/applied are the two types where PV can be included in the building. Building applied/attached PV(BAPV) indicates that the PV system is added/attached or applied to a building, whereas, building integrated PV (BIPV) illustrates the concept of replacing the traditional building envelop, such as window, wall, roof by PV. In India, applying PV on a building is growing due to India’s solar mission target for 2022. In 2015, through Jawaharlal Nehru National Solar Mission, India targeted to achieve 100 GW PV power of which 40 GW will be acquired from roof-integrated PV by 2022. By the end of December 2019, India achieved 33.7 GW total installed PV power. Also, green/zero energy/and sustainable buildings are gaining significance in India due to rapid urbanization. However, BIPV system is rarely used in India which is likely due to a lack of government support and public awareness. This work reviewed the status of BIPV/BAPV system in India. The BIPV window system can probably be the suitable BIPV product for Indian context to reduce the building’s HVAC load.

Photoelectrochemical (PEC) water splitting by direct solar irradiation has been considered as a route to produce solar fuel, but the technique is impeded by limitation of the photocathode materials. Although the LaFeO 3 photocathode has been identified as a potential candidate for hydrogen generation with excellent stability, lower current densities limit its PEC performance. Using solar concentration could prove to be an effective method to leverage its performance. In this study, we have developed a strategy to improve the current density of the LaFeO 3 photocathode by applying concentrated solar flux. The results demonstrate that the photocurrent density follows a linear relationship with flux concentration and twofold performance enhancement with 18 times of incident flux. Furthermore, the addition of H 2 O 2 to the electrolyte solution has significantly improved the photocurrent induced by LaFeO 3 because of efficient scavenging of electrons. The fabricated LaFeO 3 photocathode is translucent, and therefore, a reflector element is placed behind the substrate to redirect light back to the photocathode. The incorporation of high flux concentration, scavenger and reflector element, enhanced current density by nine times (to 0.872 mA/cm 2 ). Our results demonstrate that the concentrated solar flux-assisted LaFeO 3 photocathode will play a significant role in renewable hydrogen production, and the study will provide a direction to PEC water splitting.

Energy consumption of buildings is increasing at a rapid pace due to urbanization, while net-zero energy buildings offer a green and sustainable solution. However, limited rooftop availability on multi-story buildings poses a challenge for large-scale integration of photovoltaics. Conventional silicon solar panels block visible light making them unfeasible to cover all the surfaces of a building. Here, we demonstrate a novel dielectric grating based planar light concentrator. We integrate this functional device onto a window glass transmitting visible light while simultaneously guiding near infrared (NIR) portion of sunlight to edges of the glass window where it is converted to electricity by a photovoltaic cell. Gratings are designed to guide NIR region and realize polarization independent performance. Experimentally, we observe 0.72% optical guiding efficiency in the NIR region (700–1000 nm), transmitting majority of the visible portion for natural room lighting. Integrating solar cell at the window edge, we find an electrical conversion efficiency of about 0.65% of NIR light with a 25 mm 2 prototype. Major losses are coupling and guiding losses arising from non-uniformity in fabrication over a large area. Such a functional window combining energy generation, natural room lighting and heat load reduction could mitigate urban heat island effect in modern cities.

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