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


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.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14
Fig. 15
Fig. 16
Fig. 17
Fig. 18
Fig. 19
Fig. 20
Fig. 21
Fig. 22



Building-integrated photovoltaic/thermal


Compound parabolic concentrator


Relative error


Life cycle assessments


Root means square deviation





A :


A Ch :

Cross-section of the channel area

b ch :

Breadth of channel

c a :

Specific heat capacity (kJ/kg K)

G :

Solar radiation intensity (W/m2)

h :

Coefficient of heat transfer

h p1 :

Penalty factor

h p2 :

Penalty factor

I :

Circuit current (A)


Air mass flow rate (kg/s)

P :

Power (W)

q u :

Thermal energy (W)

q exo :

Exergy overall (W)

T :


U b :

Overall back loss coefficient from flowing air to ambient through the insulator (Wm−2 K−1)

U T :

Coefficient of conductive heat transfer from the solar cell to air through tedler

U tT :

Coefficient of overall heat transfer from glass to tedler through solar cell

U t :

Coefficient of overall heat transfer from the solar cell to ambient through glass

U L :

Coefficient of overall heat transfer from the solar cell to ambient through top and back surface of the insulation

V :

Circuit voltage (V), wind speed (m/s)

R :

Resistance (Ω)




The back surface


Solar cells














Maximum power point






Absorber plate


Reference conditions





T :




α :


β c :

Factor of solar packing cells

ɛ :


η :


λ :

Thermal conductivity (Wm1 K1)

μ :

Dynamic viscosity (kg m−1 s−1)

ρ :

Density (kg/m3)

τ :



  1. 1.

    Ghedamsi, R., Settou, N., Gouareh, A., Khamouli, A., Saifi, N., Recioui, B., Dokkar, B.: Modeling and forecasting energy consumption for residential buildings in Algeria using bottom-up approach. J. Energy Build. 121, 309–3017 (2016)

    Google Scholar 

  2. 2.

    Dokkar, B., Negrou, B., Settou, N., Imine, O., Chennouff, N., Benmhidi, A.: Optimization of PEM fuel cells for PV-hydrogen power system. J. Energy Proc. 36, 798–807 (2013)

    Google Scholar 

  3. 3.

    Dokkar, B., Settou, N., Chennouff, N.: Application des énergies renouvelables: Alimentation électrique d’une résidence. Éditions universitaires européennes, (2016)

  4. 4.

    Hussein, A.K., Walunj, A., Kolsi, L.: Applications of nanotechnology to enhance the performance of the direct absorption solar collectors. J. Therm. Eng. 2(1), 529–540 (2016)

    Google Scholar 

  5. 5.

    Youcef-Ali, S., Desmons, J.Y.: Numerical and experimental study of a solar equipped with offset rectangular plate fin absorber plate. J. Renew. Energy 31, 2063–2075 (2006)

    Google Scholar 

  6. 6.

    Liu, Y.D., Diaz, L.A., Suryanarayana, N.V.: Heat transfer enhancement in air heating flat-plate solar collectors. Transactions of ASME. J. Sol. Energy Eng. 106, 363–385 (1984)

    Google Scholar 

  7. 7.

    Zhang, H., Ma, X., You, S., Wang, Y., Zheng, X., Ye, T., Zheng, W., Wei, S.: Mathematical modeling and performance analysis of a solar air collector with slit-perforated corrugated plate. J. Sol. Energy 167, 147–157 (2018)

    Google Scholar 

  8. 8.

    Tiwari, A., Sodha, M.S., Chandra, A., Joshi, J.C.: Performance evaluation of photovoltaic thermal solar air collector for composite climate of India. J. Sol. Energy Mater. Solar Cells 90, 175–189 (2006)

    Google Scholar 

  9. 9.

    Yang, T., Athienitis, A.K.: A review of research and developments of building-integrated photovoltaic/thermal (BIPV/T) systems. J. Renew. Sustain. Energy Rev. 66, 886–912 (2016)

    Google Scholar 

  10. 10.

    Hussein, A.K.: Applications of nanotechnology to improve the performance of solar collectors—Recent advances and overview. Renew. Sustain. Energy Rev. 62, 767–792 (2016)

    Google Scholar 

  11. 11.

    Raghuraman, P.: Analytical predictions of liquid and air photovoltaic/thermal flat plate collector performance. J. Sol. Energy Eng. 103, 291–308 (1981)

    Google Scholar 

  12. 12.

    Hussein, A.K., Li, D., Kolsi, L., Kata, S., Sahoo, B.: A review of nano fluid role to improve the performance of the heat pipe solar collectors. Energy Proc. 109, 417–424 (2017)

    Google Scholar 

  13. 13.

    Hosseinzadeh, M., Salari, A., Sardarabadi, M., Passandideh-Fard, M.: Optimization and parametric analysis of a nanofluid based photovoltaic thermal system: 3D numerical model with experimental validation. Energy Convers. Manag. 160, 93–108 (2018)

    Google Scholar 

  14. 14.

    Hussein, A.K.: Applications of nanotechnology in renewable energies-A comprehensive overview and understanding. Renew. Sustain. Energy Rev. 42, 460–476 (2015)

    Google Scholar 

  15. 15.

    Bergene, T., Lovvik, O.M.: Model calculations on a flat-plate solar heat collector with integrated solar cells. J. Sol. Energy 55, 453–462 (1995)

    Google Scholar 

  16. 16.

    Touafek, K., Haddadi, M., Malek, A.: Design and modeling of a photovoltaic thermal collector for domestic air heating. J. Energy Build. 59, 21–28 (2013)

    Google Scholar 

  17. 17.

    Sarhaddi, F., Farahat, H., Bahzadmehr, A., Adeli, M.: An improved thermal and electrical model for a solar photovoltaic thermal (PV/T) air collector. J. Appl. Energy 87, 2328–2339 (2010)

    Google Scholar 

  18. 18.

    Akpinar, E.K., Kocyigit, F.: Energy and exergy analysis of a new flat-plate solar air heater having different obstacles on absorber plates. J. Appl. Energy 87, 3438–3450 (2010)

    Google Scholar 

  19. 19.

    Kim, J.H., Park, S.H., Kim, J.T.: Experimental performance of a Photovoltaic-thermal air collector. J. Energy Proc. 48, 888–894 (2014)

    Google Scholar 

  20. 20.

    Joshi, A.S., Tiwari, A.: Energy and exergy efficiencies of a hybrid photovoltaic-thermal (PV/T) air collector. J. Renew. Energy 32, 2223–2241 (2007)

    Google Scholar 

  21. 21.

    Rajoria, S.C., Agrawal, S., Tiwari, G.N., Chaursia, G.S.: Exergetic and enviroeconomic analysis of semitransparent PVT array based on optimum air flow configuration and its comparative study. J. Sol. Energy 122, 1138–1145 (2015)

    Google Scholar 

  22. 22.

    Tonui, J.K., Tripanagnostopoulos, Y.: Performance improvement of PV/T solar collectors with natural air flow operation. J. Sol. Energy 82, 1–12 (2008)

    Google Scholar 

  23. 23.

    Moshfegh, B., Sandberg, M.: Investigation of fluid flow and heat transfer in a vertical channel heated from one side by PV elements. Part I-Numerical study. Renew. Energy. 8, 248–253 (1996)

    Google Scholar 

  24. 24.

    Sopian, K., Liu, H., Kakac, S., Veziroglu, T.N.: Performance of a double pass photovoltaic thermal solar collector suitable for solar drying systems. J. Energy Convers. Manag. 41, 353–365 (2000)

    Google Scholar 

  25. 25.

    Agrawal, S., Tiwari, G.N.: Overall energy, exergy and carbon credit analysis by different type of hybrid photovoltaic thermal air collectors. J. Energy Conver. Manage. 65, 628–636 (2013)

    Google Scholar 

  26. 26.

    Shahsavar, A., Ameri, M.: Experimental investigation and modeling of a direct coupled PV/T air collector. J. Sol. Energy 84, 1938–1958 (2010)

    Google Scholar 

  27. 27.

    Tiwari, S., Tiwari, G.N.: Energy and exergy analysis of a mixed-mode greenhouse-type solar dryer, integrated with partially covered N-PVT air collector. J. Energy 128, 183–195 (2017)

    Google Scholar 

  28. 28.

    Daghigh, R., Shafieian, A.: An experimental study of a heat pipe evacuated tube solar dryer with heat recovery system. J. Renew. Energy 96, 872–880 (2016)

    MATH  Google Scholar 

  29. 29.

    Kasaeian, A., Khanjari, Y., Golzari, S., Mahian, O., Wongwises, S.: Effects of forced convection on the performance of a photovoltaic thermal system: an experimental study. J. Exp. Therm. Fluid Sci. 85, 13–21 (2017)

    Google Scholar 

  30. 30.

    Huide, F., Xuxin, Z., Lei, M., Tao, Z., Qixing, W., Hongyuan, S.: A comparative study on three types of solar utilization technologies for buildings: photovoltaic, solar thermal and hybrid photovoltaic/thermal systems. Energy Convers. Manag. 140, 1–13 (2017)

    Google Scholar 

  31. 31.

    Omer, K.A., Zala, A.M.: Experimental investigation of PV/thermal collector with theoretical analysis. Renew. Energy Focus 27, 67–77 (2018)

    Google Scholar 

  32. 32.

    Elsafi, A.M., Gandhidasan, P.: Comparative study of double-pass flat and compound parabolic concentrated photovoltaic-thermal systems with and without fins. J. Energy Convers. Manag. 98, 59–68 (2015)

    Google Scholar 

  33. 33.

    Tiwari, G.N., Mishra, A.K., Meraj, Md, Ahmad, A., Khan, M.E.: Effect of shape of condensing cover on energy and exergy analysis of a PVT-CPC active solar distillation system. J. Sol. Energy 205, 113–125 (2020)

    Google Scholar 

  34. 34.

    Wu, S.Y., Wang, T., Xiao, L., Shen, Z.G.: Effect of cooling channel position on heat transfer characteristics and thermoelectric performance of air-cooled PV/T system. Sol. Energy 180, 489–500 (2019)

    Google Scholar 

  35. 35.

    Özakin, A.N., Kaya, F.: Effect on the exergy of the PVT system of fins added to an air-cooled channel: a study on temperature and air velocity with ANSYS Fluent. J. Sol. Energy 184, 561–569 (2019)

    Google Scholar 

  36. 36.

    Good, C.: Environmental impact assessments of hybrid photovoltaic-thermal (PV/T) systems: a review. Renew. Sustain. Energy Rev. 55, 234–239 (2016)

    Google Scholar 

  37. 37.

    Ndiho, A., Wuitcha, K.N., Samah, H.A., Banna, M.: Numerical study of natural convection through a photovoltaic-thermal (PV/T) building solar chimney suitable for natural cooling. Int. J. Sci. Technol. Res. 3, 148–155 (2014)

    Google Scholar 

  38. 38.

    Boumaaraf, B., Boumaaraf, H., Slimani, M.E., Kebir, S.T., Ait-cheikha, M.S., Touafek, K.: Performance evaluation of a locally modified PV module to a PV/Tsolar collector under climatic conditions of semi-arid region. Math. Comput. Simul. 167, 135–154 (2020)

    Google Scholar 

  39. 39.

    Delisle, V., Kummert, M.A.: Novel approach to compare building-integrated photovoltaics/thermal air collectors to side-by-side PV modules and solar thermal collectors. J. Sol. Energy 100, 50–65 (2014)

    Google Scholar 

  40. 40.

    Su, D., Jia, Y., Huang, X., Alva, G., Tang, Y., Fang, G., : Dynamic performance analysis of photovoltaic-thermal solar collector with dual channels for different fluids. J. Energy Convers. Manag. 120, 13–24 (2016)

    Google Scholar 

  41. 41.

    Li, D., Li, Z., Zheng, Y., Liu, C., Hussein, A.K., Liu, X.: Thermal performance of a PCM-filled double-glazing unit with different thermo physical parameters of PCM. Sol. Energy 133, 207–220 (2016)

    Google Scholar 

  42. 42.

    Duffie, J.A., Beckman, W.A.: Solar engineering of thermal processes, 2nd edn. Wiley, New York (1991)

    Google Scholar 

  43. 43.

    Joshi, A.S., Dincer, I., Reddy, B.V.: Thermodynamic assessment of photovoltaic systems. J. Sol. Energy 83(8), 1139–1149 (2009)

    Google Scholar 

  44. 44.

    Sellami, R., Amirat, M., Mahrane, A., Slimani, M.E.A., Arbane, A., Chekrouni, R.: Experimental and numerical study of a PV/Thermal collector equipped with a PV-assisted air circulation system: configuration suitable for building integration. Energy Build. 190, 216–234 (2019)

    Google Scholar 

  45. 45.

    Saeedi, F., Sarhaddi, F., Behzadmehr, A.: Optimization of a PV/T (photovoltaic/thermal) active solar still. J. Energy. 87, 142–152 (2015)

    Google Scholar 

  46. 46.

    Rejeb, O., Sardarabadi, M., Ménézo, C., Passandideh-Fard, M.: Numerical and model validation of uncovered nanofluid sheet and tube type photovoltaic thermal solar system. J. Energy Convers. Manag. 110, 367–377 (2016)

    Google Scholar 

  47. 47.

    Orioli, A., Di Gangi, A.: A procedure to calculate the five-parameter model of crystalline silicon photovoltaic modules on the basis of the tabular performance data. J. Appl. Energy 102, 1160–1177 (2012)

    Google Scholar 

  48. 48.

    Soltani, S., Kasaeian, A., Sarrafha, H.: An experimental investigation of a hybrid photovoltaic/thermoelectric system with nanofluid application. Sol. Energy 155, 1033–1043 (2017)

    Google Scholar 

  49. 49.

    Amori, K.E., Abd-AlRaheem, M.A.: Field study of various air based photovoltaic/thermal hybrid solar collectors. J. Renew. Energy 63, 402–414 (2014)

    Google Scholar 

  50. 50.

    Chow, T.T.: A review on photovoltaic/thermal hybrid solar technology. J. Appl. Energy 87(2), 365–379 (2010)

    Google Scholar 

  51. 51.

    Jarimi, H., Abu Bakar, M.N., Othman, M., Hj Din, M.: Bi-fluid photovoltaic/thermal (PV/T) solar collector: experimental validation of a 2-D theoretical model. Renew. Energy 85, 1052–1067 (2016)

    Google Scholar 

  52. 52.

    Slimani, M.E.A., Amirat, M., Kurucz, I., Bahria, S., Hamidat, A., Chaouch, W.: A detailed thermal-electrical model of three photovoltaic/thermal (PV/T) hybrid air collectors and photovoltaic (PV) module: comparative study under Algiers climatic conditions. J. Energy Convers. Manag. 133, 485–476 (2017)

    Google Scholar 

  53. 53.

    Aoues, K., Moummi, N., Zellouf, M., Benchabane, A.: Thermal performance improvement of solar air flat plate collector: a theoretical analysis and an experimental study in Biskra, Algeria. Int. J. Ambient Energy 32, 95–102 (2011)

    Google Scholar 

  54. 54.

    Amori, K.E., Hussein, M., Al-Najjar, T.: Analysis of thermal and electrical performance of a hybrid (PV/T) air based solar collector for Iraq. J. Appl. Energy 98, 384–395 (2012)

    Google Scholar 

  55. 55.

    Agrawal, B., Tiwari, G.N.: Life cycle cost assessment of building integrated photovoltaic thermal (BIPVT) systems. Energy Build. 42(9), 1472–1481 (2010)

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Naoui Khenfer.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Appendix A

Appendix A

The following formulations are used in thermal mathematical model of the proposed PV/T collector.

The expressions for (A, B, C, D, E, F, K, S, R, W, N and Z) used in Eqs. (30), (31), (32), (33) are:

$$A = h_{{\text{w}}} + h_{{{\text{c,p}} - {\text{in}}}} ,$$

where hw is the heat coefficient due to wind, hc,p–in is the thermal insulator.

$$B = h_{{{\text{v,air}} - {\text{p}}}} + h_{{{\text{c,p}} - {\text{in}}}} + h_{{{\text{r,p}} - {\text{g}}}} ,$$

where hv,air–p is the Coefficient of convective heat transfer from the plate to air duct, hr,p–g is the aluminum plate to the glass coefficient.

$$C = h_{{{\text{r,s}} - {\text{g}}}} + h_{{\text{w}}} + h_{{{\text{v,air}} - {\text{g}}}} + h_{{{\text{r,p}} - {\text{g}}}} ,$$

where hv,air–g is the Coefficient of convective heat transfer from the glass to air duct, hr,s–g is the sky to the glass coefficient.

$$D = h_{{{\text{v,air}} - {\text{g}}}} + h_{{{\text{v,air}} - {\text{p}}}} ,$$
$$E = \frac{C}{{b_{{{\text{ch}}}} h_{{{\text{v,air}} - {\text{g}}}} }},$$

where bch is the width of channel.

$$F = \frac{{h_{{{\text{v,air}} - {\text{g}}}} }}{{Ah_{{{\text{r,p}} - {\text{g}}}} }},$$
$$K = FAB + h_{{{\text{v,air}} - {\text{p}}}} - Fh_{{{\text{c,p}} - {\text{in}}}}^{2} ,$$
$$S = - \;Eh_{{{\text{v,air}} - {\text{p}}}} - h_{{{\text{r,p}} - {\text{g}}}} ,$$
$$R = - \;EDK - SD - SAFh_{{{\text{v,air}} - {\text{p}}}} ,$$
$$W = - \;\dot{m}C_{{\text{a}}} \left( {S + KE} \right),$$

where \(\dot{m}\) is the mass flow rate, Ca is the specific heat capacity of air.

$$Z = \dot{m}c_{{\text{a}}} \frac{R}{W}.$$

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Khenfer, N., Dokkar, B. & Messaoudi, M.T. Overall efficiency improvement of photovoltaic-thermal air collector: numerical and experimental investigation in the desert climate of Ouargla region. Int J Energy Environ Eng (2020). https://doi.org/10.1007/s40095-020-00353-1

Download citation


  • PV/T system
  • Airflow
  • Plate absorber
  • Natural convection
  • Overall efficiency