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Chinese scientists have manufactured a prototype photovoltaic system that integrates phase change materials (PCM), a thermoelectric generator and thermal collectors. The three technologies aim to cool the solar panel and increase its energy generation efficiency.Scientists from Chinas Tianjin Chengjian University have manufactured an experimental photovoltaic device that integrates three different technologies aimed at improving its performance: a phase change material (PCM), a thermoelectric generator (TEG) and thermal collector devices (T).
PCMs can absorb, store and release large amounts of latent heat in defined temperature ranges. They have often been used in research for cooling photovoltaic modules and heat storage.
TEGs can convert heat into electricity through the “Seebeck effect,” which occurs when a temperature difference between two different semiconductors produces a voltage between both substances. These devices are commonly used in industrial applications to convert excess heat into electricity. However, its high cost and poor performance have so far limited its wider adoption.
“The system has good economic potential thanks to its excellent temperature control, high power generation and energy efficiency, and its use is expected to become more widespread in the future as the cost of thermoelectric chips decreases,” lead author of the research, We Li, told pv magazine .
The system uses PCM, TEG and cooling water to absorb excess heat from the photovoltaic panels, effectively controlling their temperature and prolonging their useful life. At the same time, the PCM provides a stable heat source for the TEG and the water-cooled panels provide a cold source for the TEG. The TEG generates electricity through the temperature difference between the two sides of the hot and cold sources, improving the overall power generation rate of the PV system. The cooling water recovers the remaining heat to improve the use of solar energy.
The PV-PCM-TEG-T was constructed by placing an aluminum frame on the back of the PV panel to form a cavity to embed the PCM and sealing it with an aluminum plate. The series-connected TEGs were fixed to the back of the aluminum plate with thermally conductive silicone. Additionally, a water cooling plate was placed on the other side of the TEGs.
The academics built an experimental prototype of the PV-PCM-TEG-T system and compared its performance with that of a reference PV panel without the PCM-TEG-T structure.
“In the numerical simulations, the heat transfer of the PV-PCM-TEG-T system was numerically modeled,” Li explained. “Under 24-hour operating conditions, the PV-PCM-TEG-T system demonstrates greater temperature control compared to standard PV panels.”
The proposed system was found to have 10.4% higher power output and 1.9% higher power generation efficiency than the reference system. “Under 24-hour simulation conditions, the temperature of the new system is significantly lower than that of the standard photovoltaic panel, with a maximum difference of 10.1 ºC,” explains the research group. “PCM thickness shows little influence on temperature controllability, while greater PCM thickness increases heat storage, thus increasing TE power generation.”
“Compared with standard PV panels under conditions of 3h with radiation and 3h without radiation, the system can effectively control the temperature of PV panels and improve power generation efficiency,” Li added. “The addition of TEG increases the power generation capacity; “circulating cooling water improves temperature difference, increases thermoelectric power generation capacity, and realizes heat recovery and storage.”
The researchers presented the system in the study “ Experimental and numerical study on photovoltaic thermoelectric heat storage system based on phase change temperature control ” , published in Solar Energy . |
