Chinese scientists have developed photovoltaic blinds that are said to be able to control thermal load, daylight penetration, and energy generation in tall buildings with glass facades.
The inventors assert that the blinds provide better architectural aesthetics and significant potential for energy conservation.
Chinese researchers have created an innovative dvPVBE system designed for high-rise glass-façade buildings, which integrates dynamic and vertical photovoltaic technology into the building envelope.
The novelty of the system lies in its flexibility with weather-responsive slat angles and blind positions.
“Recently, highly dynamic and weather-responsive PVBEs have been studied to further improve building energy efficiency,” the academics said.
“However, relatively complex structures are not suitable for high-rise buildings because of their weak windproofing characteristics, which prevent their large-scale application in cities.
Consequently, the development of simple, flexible, and intelligent PV shading devices continues to present significant challenges.”
In order to address these challenges, the researchers developed the proposed system as a compact external layer of windows.
In a prototype they created, the frame and blind slats were constructed using aluminum alloy, and the solar cells were incorporated into the slats.
The slats were operated by a motor concealed within the top-frame structure.
“Unlike traditional static external blinds, the slats of the dvPVBE can stop at any height of the frame and rotate between 0 degrees and 90 degrees via the precise stroke control of the motor,” they explained. “The blinds can be deployed partially or fully.”
The dvPVBE can be manually controlled by the building’s occupants or automatically through three control strategies known as power generation priority (PGP), natural daylight priority (NDP), and energy-saving priority (ESP).
Each strategy adjusts the slat angle and blind position based on inputs such as solar radiation, room occupancy, indoor lighting, and real-time electricity consumption and generation.
The blind position refers to the distance from the top frame to the bottom slat.
The PGP and ESP control strategies were further examined in a computer simulation. A 24-story office building in Beijing, China, was utilized for the simulation, with no surrounding high-rise buildings.
A representative room measuring 5 m × 5 m × 3 m on the south-facing façade with a window-to-wall ratio of 70% was simulated, with HVAC temperatures set to below 26 C in summer and above 18 C in winter.
During the weekdays, the system operated from 7:00 to 18:00, including a start-up period. The simulated PV on the slats consisted of 26 monocrystalline silicon cells per slat on 24 slats per window.
These cells were assumed to be supplied by JinkoSolar, a Chinese manufacturer, with an efficiency of 21.32%.
The slat angles could be adjusted in 5-degree increments.
The analysis focused on four typical days: the vernal equinox, summer solstice, autumnal equinox, and winter solstice.
“For the control strategies of the dvPVBE, the PGP strategy was used during non-working hours, and the ESP strategy was used during working hours,” the researcher said.
“To further demonstrate the viability of the dvPVBE in enhancing building energy efficiency and conduct a fair comparison with static PV blinds, the simulation primarily focused on evaluating the influence of adjustable slat angles on energy performance.”
The simulation revealed that the dvPVBE system demonstrated better energy efficiency in comparison to the static PVBEs all year round.
The dvPVBE was able to meet 131% of the office room’s annual energy requirement, showing a minimum increase of 226% in net energy output compared to the static system.
“For most of the daytime throughout the year in Beijing, 45° – 60° slat angles are recommended to balance the utilization of natural light and solar energy,” the academic group emphasized.
“In the early morning, large slat angles are recommended to allow sufficient daylight penetration to lower the lighting load, particularly in the winter.”
Source Dynamic photovoltaic
