A team of researchers from China and the United Arab Emirates has proposed a photovoltaic–thermoelectric generator (PV-TEG) module for use in the receiving subsystem of a laser wireless power transmission (LWPT) system. They tested the module under low, moderate, and high atmospheric turbulence conditions, finding that it mitigated thermal stress and improved PV receiver performance.
LWPT, also known as power beaming, transmits energy over long distances using a laser for transmission and a photovoltaic (PV) component in the receiving subsystem. Both single and multijunction cells are being evaluated for use in such receivers.
Thermoelectric generators (TEGs) convert heat into electricity through the Seebeck effect, which occurs when a temperature difference between two dissimilar semiconductors produces a voltage difference. TEGs are commonly used in industrial applications to recover waste heat and convert it into electricity. However, their high cost and limited efficiency have so far restricted their broader adoption.
In PV-TEG systems, the PV panel generates power during the day, while the TEG harnesses temperature differences around the cell to produce electricity at night.
“In previous studies, many researchers mainly focused on the performance of PV-TEG receivers under uniform light irradiation. This study innovatively investigated the impact of the Gaussian laser passing through atmospheric turbulence on the output performance of the PV-TEG receiver and evaluated its energy efficiency improvement compared to a traditional PV receiver under various environmental conditions,” Meng Xianlong, first author of the research, told pv magazine.
Under a Gaussian light beam with a total power of 6 W, the overall output performance of the PV-TEG system improved by 25.81% compared to a PV-only receiver, according to Xianlong.
In LWPT applications, there is a “critical” need to manage heat and energy utilization efficiently, particularly under prolonged, high-intensity laser exposure, the researchers noted.
To evaluate the thermal, electrical, and optical performance of the PV-TEG system under varying laser powers and atmospheric turbulence intensities, the team developed a multiphysics simulation model, which analyzed the effect of laser irradiation intensity on the system’s output characteristics and its capacity to absorb residual laser energy not converted by the PV cell into electricity. Ray tracing was used to calculate surface intensity, and the results were validated experimentally.
The hybrid device combined a single gallium arsenide (GaAs) solar cell for power conversion with a commercially available TEG module.
According to Xianlong, the most challenging aspect was determining the Seebeck coefficient and proving the system’s feasibility.
The team calculated the thermoelectric conversion characteristics of the TEG module under multiple coefficients. “By comparing the obtained results with the measurements from our experimental samples, we ultimately determined that the Seebeck coefficient is a fixed constant,” Xianlong explained.
To demonstrate the PV-TEG receiver’s ability to optimize the operating temperature of GaAs cells, the researchers compared the temperatures of a PV-only unit and a PV-TEG receiver under different atmospheric turbulence structure constants, with the findings showing that the PV-TEG receiver significantly reduced the operating temperature of PV cells by up to 31.94 K compared to conventional PV-only receivers.
“The results clearly indicate that the PV-TEG receiver maintains a lower operating temperature for the GaAs photovoltaic cells compared to the PV-only system under low and moderate turbulence conditions,” said the researchers. Specifically, under moderate atmospheric turbulence, the PV-TEG system exhibited a notable increase in output power, with enhancements of up to 66.06%.
They also noted that, under strong turbulence, the uneven energy distribution was introduced, but the PV-TEG receiver maintained “superior” performance by leveraging its dual energy recovery capability.
The system was presented in “Enhanced laser wireless power transmission efficiency with a novel PV-TEG hybrid receiver: dual thermal management and energy recovery,” published in Scientific Reports.
The research team included scientists from China’s Northwestern Polytechnical University, and United Arab Emirates-based Amity University and Khalifa University of Science and Technology.
Another test of the laser atmospheric turbulence effects is planned using multiple solar cells in the PV receiver. Xianlong noted that the “extremely high light intensity at the receiving end” creates a need for new requirements for heat control and PV cell system management. The group is also studying overall heat control and management of the PV in high-energy-density concentrating photovoltaic systems.
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