The modules are concentrators which house high-efficiency solar photovoltaic cells and focusing optics. The concentrators are dynamically actuated to track the sun’s movement, via the frames into which they are mounted. The ICSF systems separate the direct components of insolation to allow for cool daylighting without glare and unwanted heat gain. Direct normal insolation is collected to generate power and to reduce solar gain or re-direct into heating systems during cool months. Diffuse daylight from the sky dome, in comparison, filters through the system and into the occupied space, with minimal attenuation or spectral change, meaning that the natural color of daylight is allowed to flood interior spaces without heating up the building.
Additionally, in tested prototypes, energy is harvested from concentrators via hydronics, generating energy storage at temperatures that are sufficient to drive thermodynamic processes such as sorption cooling (Novelli, Dyson, Renewable Energy, 2021).
Technical Significance, Innovation and Impact
Buildings consume roughly one-third of global primary energy. If we are to achieve societal goals to shift towards ‘net zero’ buildings, then more effective strategies are required to convert on-site solar energy. With this area of research, we have developed 7 different generations of multifunctional building façade systems, and have thus far demonstrated potentially game-changing results that would offer far more functional and aesthetic value. Using less than 1% of the semiconductor materials of conventional systems, integrated systems were designed for disassembly (to be recycled), tested and developed to expand opportunities for net-zero commercial architecture by synergistically reducing cooling loads, lighting loads, and contributions to urban heat island effects, while converting ambient solar energy resources for internal demands. ICSF #7 or The Building Integrated, Transparent, Concentrating, Photovoltaic and Thermal collector (BITCoPT) optically separates diffuse and direct irradiance, transmitting diffuse light for illumination and views.
Direct irradiance (which is often rejected in commercial buildings to control glare and cooling loads) is intercepted by BITCoPT and converted into electricity and thermal energy. A prototype was tested, demonstrating 43.6% cogeneration efficiency (at a 58 °C operating temperature) relative to direct normal irradiance transmitted through the building's exterior glazing, and 39.0% at 70 °C (which could supply active thermal processes at nominal coefficients of performance). An analytical model was calibrated with observed data, showing good correlation. By substituting parameter values for projected upgrades (to optics, cell type and exterior glazing) into the BITCoPT model, simulated cogeneration efficiency increased to 71.2% at 70 °C (31.2% electrical, 40.0% thermal).
ICSF is a research and development area for high performance solar systems that are conceived to holistically address a building’s simultaneous requirements for daylighting quality, electricity, hot water, and control of solar heat gain. The system comprises of an array of largely transparent modules layered directly inside building envelope glazing or within the layers of a roof canopy system.
Can we dramatically increase the effective capture and transformation of solar energy?
Image: Integrated Concentrated Solar Facade