# Numerical and Experimental Investigation on a Thermo-Photovoltaic Module for Higher Efficiency Energy Generation

- 238 Downloads
- 1 Citations

## Abstract

One major problem of solar cells is the decrease in efficiency due to an increase in temperature when operating under constant irradiation of solar energy. The combination of solar cell and a thermoelectric generator is one of the methods proposed to solve this problem. In this paper, the performance of thermo-photovoltaic system is studied experimentally as well as through numerical simulation. In the experimental part, design, manufacture and test of a novel thermo-photovoltaic system assembly are presented. Results of the assembled system showed that with reduction of one degree (Centigrade) in the temperature of solar cell under investigation, and about 0.2 % increase in the efficiency will be obtained in comparison with given efficiency at that specified temperature. The solar cell in a hybrid-assembled system under two cooling conditions (air cooling and water cooling) obtained an efficiency of 8 % and 9.5 %, respectively, while the efficiency of a single cell under the same radiation condition was 6 %. In numerical simulation part, photo-thermoelectric performance of system was analyzed. Two methods for evaluation of thermoelectric performance were used: average properties and finite element method. Results of simulation also demonstrate an increase in solar cell efficiency in the combined system in comparison with that of the single cell configuration.

## Keywords

Solar cell Thermoelectric Thermo-photovoltaic Efficiency## List of symbols

*A*Solar cell area (m\(^{2}\))

*a*Absorption coefficient

- \(A_n \)
Cross-sectional area of n-type arm (m\(^{2})\)

- \(A_p \)
Cross-sectional area of p-type arm (m\(^{2})\)

*E*Solar irradiation (W\(\cdot \)m\(^{-2}\))

- \(E_g \)
Band-gap energy (eV)

*h*Convective heat transfer coefficient (W\(\cdot \)m\(^{-2}\) \(\cdot \hbox {K}^{-1}\))

*I*Electric current (A)

- \(I_0 \)
Reverse saturation current (A)

- \(I_{\mathrm{max}} \)
Electric current of solar cell at maximum power manner (A)

- \(I_{sc} \)
Short-circuit current (A)

*j*Current density (A\(\cdot \)m\(^{-2}\))

*K*Effective conductance of thermoelectric couple (W\(\cdot \)K\(^{-1}\))

- \(K_{FF} \)
Fill factor

*k*Boltzmann constant: \(1.38 064 852\times 10^{-23}\)J\(\cdot \)K\(^{-1}\)

- \(k_n \)
n-Type arm’s thermal conductivity (W\(\cdot \)m\(^{-1}\cdot \)K\(^{-1}\))

- \(k_p \)
p-Type arm’s thermal conductivity (W\(\cdot \)m\(^{-1}\cdot \)K\(^{-1}\))

*L*Thickness of the junction (m)

- \(N_n \)
n-Type dopant concentration (atom\(\cdot \)cm\(^{-3}\))

- \(N_p \)
p-Type dopant concentration (atom\(\cdot \)cm\(^{-3}\))

- \(n_{ph} \)
Number of photons with enough energy

- \(m_0 \)
Electron rest mass: \(9.10 938 356\times 10^{-31}\hbox { kg}\)

- \(m_n^*\)
Effective mass of electron (kg)

- \(m_p^*\)
Effective mass of hole (kg)

- \(P_{\mathrm{Cell}} \)
Output power of solar cell (W)

- \(P_{\mathrm{max}} \)
Maximum power output from cell (W)

- \(P_{\mathrm{TEG}} \)
Output power of thermoelectric generator (W)

*q*Electron charge, \(1.6 021 765\times 10^{-19}\,{^{\circ }}\hbox {C}\)

- \(Q_c \)
Heat transferred from TEG to the heat sink (W)

- \(Q_h \)
Heat transferred to hot side of TEG (W)

*R*Effective electric resistance of thermoelectric couple (\(\Omega \))

- \(R_L \)
External load resistance (\(\Omega \))

- \(T_{\mathrm{air}} \)
Ambient temperature (\({^{\circ }}\hbox {C}\))

- \(T_{\mathrm{ave}} \)
Average operating temperature of thermoelectric (\({^{\circ }}\hbox {C}\))

- \(T_c \)
Cold-side temperature (\({^{\circ }}\hbox {C}\))

- \(T_{\mathrm{Cell}} \)
Solar cell temperature (\({^{\circ }}\hbox {C}\))

- \(T_h \)
Hot-side temperature (\({^{\circ }}\hbox {C}\))

- \(T_n \)
n-Type arm temperature (\({^{\circ }}\hbox {C}\))

- \(T_p \)
p-Type arm temperature (\({^{\circ }}\hbox {C}\))

- \(T_{\mathrm{Sky}} \)
Sky effective temperature (\({^{\circ }}\hbox {C}\))

- \(V_{\mathrm{max}} \)
Voltage of solar cell at maximum power manner (V)

- \(V_{\mathrm{oc}} \)
Open-circuit voltage (V)

*Z*Figure of merit (1\(\cdot \)K\(^{-1}\))

## Greek

- \(\alpha _c \)
Absorptivity

- \(\alpha _{pn} \)
p–n Junction Seebeck coefficient (V\(\cdot \)K\(^{-1}\))

- \(\epsilon \)
Emissivity

- \(\eta _{\mathrm{cell}} \)
Efficiency of solar cell (%)

- \(\eta _{\mathrm{total}} \)
Total efficiency of module (%)

- \(\gamma \)
Thompson coefficient (V\(\cdot \)K\(^{-1}\))

- \(\pi \)
Peltier coefficient of p–n couple (V)

- \(\rho _n \)
Electric resistivity of n-type arm (\(\Omega \)m)

- \(\rho _p \)
Electric resistivity of p-type arm (\(\Omega \)m)

- \(\rho \)
Absorptivity

- \(\sigma \)
Stefan–Boltzmann constant: \(5.69\times 10^{-8 }\) W\(\cdot \)m\(^{-2}\) \(\cdot \) K\(^{-4}\)

- \(\tau _n \)
Life time of electron (s)

- \(\tau _p \)
Life time of hole (s)

## References

- 1.W. Liao, X. Yan, G. Chen, Z. Ren, Recent advances in thermoelectric nanocomposites. Nano Energy (2011)Google Scholar
- 2.J. Nelson,
*The Physics of Solar Cells*(Imperial College Press, London, 2003)CrossRefGoogle Scholar - 3.Renewables, Global Status Report. REN
**21**, 2010 (2010)Google Scholar - 4.Renewables, Global Status Report. REN
**21**, 2016 (2016)Google Scholar - 5.W. Sark, Feasibility of photovoltaic–thermoelectric hybrid modules. Appl. Energy
**88**(8), 2785–2790 (2011)CrossRefGoogle Scholar - 6.T. Cheng, C. Cheng, Z. Huang, G. Liao, Development of an energy-saving module via combination of solar cells and thermoelectric coolers for green building applications. Energy
**36**, 133–140 (2011)CrossRefGoogle Scholar - 7.T.T. Chow, A review on photovoltaic/thermal hybrid solar technology. Appl. Energy
**87**, 365–379 (2010)CrossRefGoogle Scholar - 8.D. Kraemer, L. Hu, A. Muto, X. Chen, G. Chen, M. Chiesa, Photovoltaic-thermoelectric hybrid systems: a general optimization methodology. Appl. Phys. Lett.
**92**, 243503-1–243503-3 (2008)Google Scholar - 9.V. Verma, A. Kane, B. Singh, Complementary performance enhancement of PV energy system through thermoelectric generation. Renew. Sustain. Energy Rev.
**58**, 1017–1026 (2016)CrossRefGoogle Scholar - 10.T. Cui, Y. Xuan, Q. Li, Design of a novel concentrating photovoltaic-thermoelectric system incorporated with phase change materials. Energy Convers. Manage
**112**, 49–60 (2016)CrossRefGoogle Scholar - 11.E. Karima, Amori, Hussein M. Taqi Al-Najjar, Analysis of thermal and electrical performance of a hybrid (PV/T) air based solar collector for Iraq. Appl. Energy
**98**, 384–395 (2012)CrossRefGoogle Scholar - 12.R. Siegel, J.R. Howel,
*Thermal Radiation Heat Transfer*, 3rd edn. (Taylor & Francis, London, 1992)Google Scholar - 13.K. Drabczyk, P. Panek, Silicon-based solar cells Characteristics and production processes. Institute of Metallurgy and Materials Science of Polish Academy of Sciences (2012)Google Scholar
- 14.J.P. Holman,
*Heat Transfer*, 10th edn. (McGraw Hill, Newyork, 2010)Google Scholar - 15.M. Altman,
*Elements of Solid-State Energy Conversion*(American Book Company, New York, 1969)Google Scholar - 16.George Walter Sutton,
*Direct Energy Conversion*(McGraw Hill, New York, 1966)Google Scholar - 17.Y.-G. Deng, J. Liu, Recent advances in direct solar thermal power generation. J. Renew. Sustain. Energy
**1**, 052701-1–052701-23 (2009)Google Scholar - 18.M.R. Eslami,
*A First Course on Finite Element Analysis*(AKU Press, Washington, 2003)Google Scholar - 19.T. Seetawan, U. Seetawan, A. Ratchasina, S. Srichai, K. Singsoog, W. Namhongsa, C. Ruttanapun, S. Siridejachai, Analysis of thermoelectric generator by finite element method. Proc. Eng
**32**, 1006–1011 (2012)CrossRefGoogle Scholar - 20.Release 11.0 Documentation for ANSYSGoogle Scholar
- 21.B. Sherman, R.R. Henkes, R.W. Ure, JR, Calculation of efficiency of thermoelectric devices. Appl. Phys.
**31**(1), 10–16 (1960)Google Scholar - 22.Jasprit Singh,
*Electronic and Optoelectronic Properties of Semiconductor Structures*(Cambridge University Press, Cambridge, 2003)CrossRefGoogle Scholar - 23.M. A. Green, K. Emery, Y. Hishikawa, W. Warta, E. D. Dunlop, Solar cell efficiency tables. Prog. Photovoltaic Res. Appl. (2013)Google Scholar