Overall efficiency improvement of photovoltaic-thermal air collector: numerical and experimental investigation in the desert climate of Ouargla region

• Published in: International journal of energy and environmental engineering Vol. 11; no. 4; pp. 497 - 516
• Main Authors: Khenfer, Naoui, Dokkar, Boubekeur, Messaoudi, Mohamed Taher
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2020; Springer; Springer Nature B.V
• Subjects: Air flow; Arid climates; Climate; Climatic conditions; Convection; Cooling systems; Deserts; Efficiency; Energy; Energy efficiency; Energy use; Exergy; Free convection; High temperature; HVAC equipment; Original Research; Photovoltaic cells; Photovoltaics; Properties; Renewable and Green Energy; Straight channels; Temperature requirements; Thermodynamic efficiency; Algeria; Airflow; Natural convection; Overall efficiency; Plate absorber; PV/T system
• ISSN: 2008-9163; 2251-6832
• DOI: 10.1007/s40095-020-00353-1

In the Ouargla region, the desert area of Algeria, photovoltaic fields (PV) suffer from hard climate conditions with high-temperature levels. This temperature level causes a significant fall of PV cells efficiency which requires an integrated cooling system. For achieving this purpose, a thermal part based on airflow provided along a straight channel under the PV module (150 W) is added. It extracts the accumulated heat by air natural convection, then, the airflow passes through an upper glass extension (0.56 m) to reinforce the heat collection. The evaluation of the whole system performance is experimentally conducted by performing several variations of operating parameters and air channel depth. This photovoltaic-thermal (PV/T) system has modeled by a set of balanced energy equations that are resolved numerically using Matlab software. The experimental results show that the increase in the channel depth causes a significant reduction of thermal efficiency and a slight effect on the electrical one. The numerical data are compared and validated by the experimental results, where the characteristic curves (efficiencies, polarization, powers, temperatures) show good concordance with experimental data. The root means square of percentage deviation (RMSD) is between 1.75% and 16.25%. For a channel depth of 10 cm, the energy and exergy efficiency reach their mean values of 58.5% and 14.7%, respectively. The glass extension of 1.6 m gives a net improvement of 5% in the overall energy efficiency.