A group of researchers from South Africa's Central University of Technology has designed a solar module integrating a cooling system relying on a thermoelectric cooler (TEC).
TECs can convert heat into electricity through the “Seebeck effect”, which occurs when a temperature difference between two different semiconductors produces a voltage between the two substances. The devices are commonly used for industrial applications to convert excess heat into electricity. However, their high costs and limited performance have thus far limited their adoption on a broader scale.
“The PV-TEC system proposed in this study entails a PV panel integrated with a TEC device, affixed to its reverse side, a heatsink interconnected with the opposing face of the thermoelectric device, and a switching mechanism,” the scientists explained. “The TEC is powered by the PV panel it is intended to cool.”
The group conducted a numerical simulation to assess the performance of the system. In addition, an optimization function was set to maximize the output while trying to keep a targeted temperature of between 23 C and 27 C when the cell temperature exceeds 25 C. The PV panel used in the simulation had an output of 100 W, an efficiency of 17.8%, and a size of 20,200 cm3. The TEC had a maximum current of 6.1 A, a maximum voltage of 17.2 V, and a size of 6.08 cm3. The heat sink had a thermal resistance of 2.6 C/W and a size of 39.2 cm3.
“The scenario under consideration involves using meteorological data obtained from Bloemfontein, Free State, South Africa,” said the researchers. “The specific dataset encompasses diffuse horizontal, diffuse normal, and global horizontal irradiance, along with ambient temperature values, delineating a typical winter day on July 17, 2021, and a summer day on January 17, 2021.”
The operation of the system was analyzed for both a summer day and a winter day and its performance was compared to a reference PV panel without the TEC and the heat sink. Under the simulated winter conditions, the cell temperature never rose above 25 C, so the TEC was not active. Therefore, in both the PV-TEC case and the reference case, the peak temperature was recorded at 22.9 C, the constant power output was 86.9 W, and the total power production stood at 363.47 Wh.
In the summer case, however the TEC did kick into action, and allowed the panel to reach a peak output of 104.1 W, compared to 94.4 W in the reference case. The peak temperature in the reference was 36.1 C, while the PV-TEC did not breach 25 C. In the TEC case, it achieved an energy output of 603.60 Wh, compared to 547.65 Wh in the reference. “The results from our proposed model demonstrated a substantial improvement in output power, specifically by 9.27 % during the summer,” highlighted the academics.
Based on these results, the researchers moved to conduct an economic analysis with an assumed life of 20 years for the PV and the PV-TEC, as well as a 10% annual increase in electricity prices and a 6% interest rate. While the initial price of the 100 W solar panel alone was assumed at 1,235 ZAR ($66.9), the total cost for the PV-TEC case was 1,562.77 ZAR.
“The break-even point manifests relatively early within the project’s operational lifespan. To be precise, it transpires at the 6.5-year mark,” concluded the scientists. “The economic analysis further resulted in a cost saving of 2,905.61 ZAR, which is a 10.56 % project lifetime saving over 20 years.”
The system was presented in “Enhancing photovoltaic operation system efficiency and cost-effectiveness through optimal control of thermoelectric cooling,” published in Solar Energy Materials and Solar Cells.
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Is that net or gross? TEC’s consume about 60w to create the peltier effect. Seems to be a wash.
I think the idea is good but the presentation of the thermoelectric aspect is misleading — it has become a norm of researchers to confuse the explanation of thermoelectricity due to ignorance of its nomenclature and definitions.
Thermoelectricity is based on three effects — the Seebeck effect, Peltier effect and the Thompson effect and associated with is Joule or Ohmic heating. The latter (Thompson effect) is seldom practically manifested / applied.
Thermoelectricity based on Seebeck effect is practically achieved using Thermoelectric Generators (TEG) — a DC voltage is generated when there is a temperature difference on the hot and cold sides of the device.
Thermoelectricity based on Peltier effect is practically achieved using the Thermoelectric Coolers (TEC) — applying DC voltage to the device generates cold and heat on both sides of the device and reversing the applied voltage polarity reverses the hot and cold sides.
Now, in the aforementioned study /paper, TEG and TEC have been used interchangeably — which is wrong, as it’s confusing, especially since a TEG can be used as a TEC and vice versa.
Because Thermoelectric Devices (TED) can be used interchangeably as TEG and TEC, it always prudent for researchers to always clarify which exactly they’re refering to and stick to it!!!! When they talk of TEC — they should be talking of cooling or heating — they can’t be talking of power generation, even though it can be used to generate power. If TEC as in Peltier cooler is used to generate power, then they should clarify it. I understand TEC has been branded as Peltier modules (e.g. TEC-xxxxx) and going by that definition, it refers to the cooling/heating aspects of thermoelectricity but in reality, TEC is often used for power generation, and if this is the case, then it should be called TEG and not TEC to avoid confusion. Better, it should just be called TED and when used for cooling/heating, called it TEC and when used for power generation, called it TEG. Don’t MIX both terminologies to mean the same thing !!!