Solar windows generate electrical and thermal energy
Jun 30, 2022
Scientists at the Hong Kong University of Science and Technology have developed a dual-band selective solar harvesting (SSH) window based on transparent photovoltaic (TPV) and transparent solar absorber (TSA). TSA is used to convert ultraviolet (UV) or near-infrared (NIR) light into thermal energy.
The collected thermal energy is extracted by ventilating the air and can be used to heat indoor spaces during the cold season or to reduce the indoor cooling load during the hot season," they explain. We demonstrated a visible light transmission of 42% for the SSH windows, a solar-to-electricity conversion efficiency of 0.75%, and a ventilation air temperature increase of 10 degrees Celsius."
The team used a luminescent solar concentrator (TPV) based on copper indium sulphide and zinc sulphide (CuInS2/ZnS) quantum dots (QD) as an external window. It is capable of collecting UV light and transmitting it to an opaque photovoltaic device located at the edge of the transparent substrate for power generation. And the TSA is used to create the inner side of the window that generates and collects heat.
The team says: "The heat energy is mainly extracted from the ventilated air inside the gap and used for various purposes, such as heating indoor spaces during the cold season."
The academics created a 30cm x 30cm x 2.4cm prototype by assembling the TPV element with the TSA on the inside. They claim that the device exhibits significant visible light transmission and is capable of generating 6 watts of electricity and approximately 150 watts of heat per square metre.
They say: "The thermal energy is 25 times more than the electricity generated, which shows that collecting thermal energy is of utmost importance for building-integrated solar collection windows. The overall effective efficiency of heat energy collection through air ventilation is estimated to exceed 30% under typical operating conditions for building space heating applications."
They describe the results in their recent article "Selective Solar Harvesting Windows for Full-Spectrum Utilization" published in Advanced Science. The results of the study are described in the article "Selective Solar Harvesting Windows for Full-Spectrum Utilization" in Science.
They say, "SSH windows can save up to 61.5 per cent of annual heating, ventilation and air conditioning (HVAC) energy compared to ordinary glass, and they can generate 19.1 per cent of annual energy savings."
