Optimization of the performance of double-façades with integrated photovoltaic panels and motorized blinds

Double-façades with integrated photovoltaic panels may be employed to generate electricity, thermal energy and for daylighting. A theoretical study of double-façades with integrated photovoltaics (PV) and motorized blinds is presented, which investigates the effect of various design parameters in order to maximize the conversion of solar radiation to useful energy. Two configurations of the façade with a lower section with integrated PV and an upper Vision (viewing) section with motorized blinds, are examined. A one-dimensional finite-difference thermal model is developed, with an algorithm that iteratively determines which convective heat transfer coefficient correlation to use for each surface inside the cavity using expressions that consider system characteristics and temperature distribution. When PV modules are installed in the middle of the cavity, air flows on both sides, increasing PV section overall (thermal-electric) efficiency by about 25%, but lowers electricity generation by 21%. Integrating 0.015 m long, 0.002 m wide fins to the PV back plate leads to a similar increase in efficiency without compromising electricity generation. Placing the blind in the middle of the cavity increases the Vision section efficiency by 5%. Using this approach to optimize performance can lead to combined thermal-electric efficiencies of over 60%.