Novel and industrially applicable cooling element for photovoltaic bifacial modules

Novel and industrially applicable cooling element for photovoltaic bifacial modules

Wix, Lyndon (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Photovoltaic Materials and Devices)

Isabella, O. (mentor)
Ziar, H. (graduation committee)

Delft University of Technology

Electrical Engineering | Sustainable Energy Technology

2021-03-18

Rising global temperatures have shifted mankind’s methods of energy production towards a more sustainable manner. Solar energy technologies have become one of the world’s leading methods of producing clean, sustainable energy. However, this technology has been facing some adversities in the field of thermal management. The majority of solar modules in the commercial market are monofacial modules, for which many thermal management solutions exist. For bifacial solar modules, this field is still being researched. This, together with the fact that bifacial modules are projected to reach a 40% market share by the year 2028, prompts the need for thermal management solutions for this technology. The proposed solution is an integrated heat sink (IHS) built in a bifacial solar module. This was thoroughly researched using the multiphysics, FEM-based software COMSOL. The geometry was drawn using the COMSOL environment and a hybrid mesh was created to accommodate the module. Initial issues and computation errors led to decreasing of model dimensions. A 1 cm by 1 cm glass bifacial module was created and debugged successfully. This model was then simulated using two COMSOL studies: ’Heat Transfer in Solids’ and ’Surface-to-Surface Radiation’. All of these simulations were performed using four illumination combinations (front illumination/back illumination [W/m2]): 1000/50; 1000/100; 1000/200 and 1000/300. After successful simulations of the 1 cm by 1 cm model, the model was scaled up to a 4 by 4 (67.31 cm by 67.31 cm) glass bifacial module. The results for both the 1 cm by 1 cm module and the 4 by 4 module were promising. In the case of 1000 W/m2 front illumination and 300 W/m2 back illumination, the 1 cm by 1 cm solar cell showed a temperature drop of 0.92 degrees Celsius and a relative efficiency gain of 0.359%. The solar cells in the 4 by 4 module showed a temperature drop of 1.33 degrees Celsius and a relative efficiency gain of 0.519%. Next, temperature simulations were performed with varying IHS thickness, from 1 mm to 10 mm. Taking into consideration that with increase thickness the temperature did not reduce significantly and that the module weight was being increased, a 1 mm IHS was found to be the most beneficial. Yield calculations were performed on a 2 by 2 (34.29 cm by 34.29 cm) bifacial module, both with and without the utilization of the IHS. It was found that with the utilization of the IHS, the financial gain was 0.05 euros/m2/year. Lastly, lifetime prediction analyses were performed to receive insight on the effect of the IHS on the lifetime of a bifacial module. It was found that the lifetime gain for a bifacial module with the IHS is about 26 days, corresponding to a relative lifetime gain of 0.68%. It should be noted however, that the lifetime of a module without the IHS under the simulation conditions was 10.27 years, far below commercially reported lifetimes. This is due to a high maximum operational temperature and a large difference between the minimum and maximum operational temperature.
The proposed integrated heat sink showcased positive effects in temperature management and efficiency gain in bifacial solar modules. The use of a hybrid mesh proved beneficial for the computation time and different scenarios can now be simulated. However, yield calculations only showed a very small financial gain and lifetime prediction analyses showed a very small lifetime gain. Further improvements include a design that can increase the heat transfer of the IHS, such as varying the thickness of the bottom glass layer or utilizing a transparent backsheet. The possibility of connecting the IHS to the frame of the module to further increase the heat transfer to the environment should be investigated. Also, different material options for the IHS and the addition of heat dissipation fins should also be researched.

Bifacial PV
Thermal management

http://resolver.tudelft.nl/uuid:18f59767-dcd9-49cf-af46-4f771a3ae930

2024-03-18

Student theses

master thesis

© 2021 Lyndon Wix