BIPV-powered smart windows utilizing photovoltaic and electrochromic devices.

Area of Science:

• Materials Science
• Energy Science
• Optoelectronics

Background:

• Smart windows offer dynamic control over building illumination and energy efficiency.
• Building-integrated photovoltaics (BIPV) present an opportunity for self-powered building systems.
• Electrochromic (EC) technology enables tunable light transmission in windows.

Purpose of the Study:

• To propose and characterize a novel self-powered smart window system.
• To integrate a BIPV panel with an all-solid-state EC stack for illuminance control.
• To evaluate the performance of different EC stack configurations.

Main Methods:

• Fabrication and characterization of two distinct all-solid-state EC stacks: ITO/WO(3)/Ta(2)O(5)/ITO and ITO/WO(3)/lithium-polymer electrolyte/ITO.
• Modulation of BIPV panel output voltage to control the EC stack voltage.
• Measurement of indoor illuminance under varying light conditions.

Main Results:

• The ITO/WO(3)/lithium-polymer electrolyte/ITO EC stack demonstrated high absorptance (approx. 99% at 3.5 V).
• The smart window system effectively maintained indoor illuminance within the 750-1,500 Lux range.
• Optimal performance was achieved with a 1.0 μm electrolyte thickness under simulated Taiwanese summer conditions.

Conclusions:

• A functional self-powered smart window system integrating BIPV and EC technology has been successfully demonstrated.
• The use of a lithium-polymer electrolyte in the EC stack is advantageous for high absorptance and performance.
• This technology holds promise for enhancing indoor environmental quality and energy savings in buildings.