حصاد الطاقة الشمسية بأستخدام نظام هجين متكامل (كهروضوئي-كهروحراري)

Solar Energy Harvesting Utilizing Photovoltaic– Thermoelectric (PV-TEG) Integrated Hybrid System

Integrating photovoltaic and thermoelectric generators requires special attention, since both modules have a diametrically opposed relation with temperature. The TEG’s conversion efficiency depends on attaining a high-temperature difference, whereas the PV needs a low temperature to produce high efficience. So, correct and efficient integration of the photovoltaic cells with the thermoelectric modules is the main issue for enhancing the hybrid system’s performance and increasing electrical power output. The methods to achieve this: include adopting an effective thermoelectric cooling system to ensure the maximum temperature is obtained and detecting the optimal number and appropriate distribution of the TEG modules that will cover the back surface of the PV model.
The present study included numerical simulation and experimental study to examine performance of (PV-TEG) a hybrid system. Firstly, a numerical and analytical study was conducted for the different hybrid system models with different numbers and distributions of the thermoelectric items at solar radiation of 1000 (W/m2), ambient temperature of 28˚C, and wind speed of 0 (m/s) as a boundary conditions. All the hybrid system models were coupled by cold side of TEG modules, with heat exchanger (shell and tube) that water circulating through it. The main hybrid system models were four models: included S1 model (PV-204 items of TEG), S2 model (PV-94 items of TEG), S3 model (PV-85 items of TEG), and S4 model (PV-50 items of TEG) hybrid systems. The results showed that the (S4) model of a hybrid system was optimum model. To show the reliability degree of the software used in the current work and the accuracy of the numerical results of this thesis, the analytical results of PV/T system performance were verified. By comparing these results with the results of previous studies in the same field and under almost the same conditions, the maximum difference that does not be more than 4 % and the smallest difference is 0.4 % between the results. So, it was concluded that the software was built correctly and gave acceptable results to a large degree.
Secondly, the optimum model (S4) hybrid system performance has been investigated in an indoor experimental study. The performance of the PV system and PV/T system were then experimentally and numerically put to comparison with that of the S4 model hybrid system. According tofindings, showed that the PV-TEG (S4) model’s output power was higher under identical operating conditions than that the photovoltaic panel and the PV/T system, respectively, by (36.94 %) and (16.8 %) numerically and 31.66 % and 16.5 % experimentally. Also, It can be seen that the average front surface of PV module in the PV-TEG (S4) hybrid system was higher by 4.5 % and 5.7 % than that PV/T system and lower by 29 % and 30 % than that the photovoltaic panel, numerically and experimentally, respectively. In addition to electrical efficiency ( ηel ) of the PV-TEG hybrid system were about (6.2 and 5.83) % in numerical and experimental tests, respectively and higher than that of the PV module and PV/T system.
The effect of the solar radiation on the hybrid system performance had studied at constant ambient temperature. The results showed an increasing hybrid system output power with increased solar radiation. The maximum obtained power regarding for the hybrid system was 39.4 W at solar radiation of 2000 (W/m²).
Finally, a comparison has performed between the experimental and numerical outcomes of the current study, and a good agreement was noticed between them. The results showed that the difference percentage of the PV module average front surface temperature (Tsc) in the PV panel, PV/T system, and PV -TEG hybrid system between numerical and experimental results were (2.9, 4.5, and 3.5) % respectively. At the same time, the difference percentage of the electrical output power ( Eel) between numerical and experimental results in the PV panel, PV/T system, and PV -TEG hybrid system is (2.2, 6.3, and 6) %, respectively. This comparing result indicates that the current work was done according to what was planned and in a way that ensures that errors were avoided as much as possible. The results highlight that the integration of TEG modules with the PV panel as the S4 model hybrid system was the best solution for harvesting the solar radiation and converting the wasted heat in the PV into additional output power.