**3. Efficiency improvement using nanofluid**

Integrating the heat receivers with the conventional PV system is found to elevate both electrical and thermal efficiencies. Several fluids such as water or nanofluids can be used in these receivers to remove heat so as to improve the efficiency of the system. Studies have proved that nanofluid based PV/T system outperforms conventional PV system and water-based PV/T system. Soltani et al. [30] used five different methods for PV cooling (natural cooling, forced air cooling, water cooling, *SiO*<sup>2</sup> -water nanofluid cooling and *Fe*<sup>3</sup> *<sup>O</sup>*<sup>4</sup> -water nanofluid cooling) to improve the performance. They found that *SiO*<sup>2</sup> -water nanofluid cooling increased the efficiency by 3.35% and *Fe*<sup>3</sup> *<sup>O</sup>*<sup>4</sup> -water nanofluid cooling increased the efficiency by 3.13% as compared to the natural cooling. Hussien et al. [31, 32] found enhancement in the thermal and electrical efficiency of PV/T system by application of *A l* <sup>2</sup> *O*<sup>3</sup> /*water* nanofluid as a coolant. Experimentation was carried out at constant flow rate of 0.2L/s and nanoparticles concentration of 0.3%. Results showed the increase in thermal and electrical efficiency when temperature was decreased from 79.1 to 42°C. Thermal and electrical efficiency of system enhanced up to 34.4% and 12.1% respectively using nanofluid. Ebaid et al. [33] used *TiO*<sup>2</sup> water-polyethylene glycol nanofluid and *Al*<sup>2</sup> *<sup>O</sup>*<sup>3</sup> water cetyltrimethylammonium bromide nanofluid (with 0.01, 0.05, and 0.1 wt% concentration at a flowrate of 500–5000 ml/min) to test the efficiency enhancement of PV module via the cooling process. Pertaining to the results, *Al*<sup>2</sup> *<sup>O</sup>*<sup>3</sup> nanofluid decreased the cell temperature by 13.83% and *TiO*<sup>2</sup> reduced the temperature by 11.2% at 5000 ml/min relative to water cooling. The best performance was witnessed in case of *TiO*<sup>2</sup> nanofluid cooling, it produced 50% more average efficiency compared to the water cooling (0.82% for *TiO*<sup>2</sup> and 0.48% for water cooling compared with no cooling). Karami and Rahimi [34] performed experiments to investigate the enhancement in the efficiency of PV module being cooled by the Boehmite (AlOOOH-x*H*<sup>2</sup> *<sup>O</sup>*) based nanofluid flowing inside microchannel at the rear end of the PV module. The results showed that the maximum increase in the electrical efficiency due to cooling as compared to the without cooling power output was found to be 27.12% at a concentration ratio of 0.01 wt.% and 300 ml/min flowrate. Similarly, Sardarabadi et al. [64] observed as much as 9.75% electrical efficiency increment for silica/water nanofluid based PV/T system as compared to uncooled system. **Figures 3** and **4** depict the maximum efficiencies of PV/T systems obtained by different researchers.

**Figure 3.** Maximum efficiency for obtained by researchers with Nanofluid cooling.

overall efficiency as well as greatest merit function. Hassani et al. [26] numerically investigated the effect of cooling on PV performance. The results revealed that PV system with optical filter (containing Ag-Water nanofluid) held above the PV surface along with thermal receiver (containing CNTs) at the rear end of PV, performed best in terms of high-grade energy as compared to conventional PV, PV being cooled by water only, PV being cooled by CNTs and PV being cooled by CNTs at rear end and optical filter containing water held at upper surface of the panel. Optical filter containing nanofluid was able to absorb both UV and IR spectrum and it only allowed the radiation in range of PV absorptivity spectrum (400-1200 nm). Whereas, optical filter containing water could only absorb IR spectrum. Saroha et al. [27] tested the effect of silver and gold based nanofluid working as optical filters in PV/T system. The results revealed that unwanted wavelengths were more absorbed by silver as compared to gold based nanofluid. Silver/water nanofluid based PV/T system approached 9.6% electrical, 67.8% thermal and 78.4% overall efficiency. Whereas, gold/water nanofluid based PV/T system achieved 9% electrical, 67.6% thermal and 76.6% overall efficiency. Jin et al. [28] investigated the effect of liquid optical filter based on magnetic electrolyte nanofluid for PV/T system. Electrolyte

O4

compared to the double pass channel in which fluid flows in a single channel [29].


<sup>2</sup> *O*<sup>3</sup>

**3. Efficiency improvement using nanofluid**

containing methylene blue or copper sulfate, in this way they obtained two stable ENF filters. By adjusting the volume fraction of nanoparticles and molar fraction, more optimized ENF is produced. This ENF presents more better results compared to the simple liquid filters. Merit function of this newly developed ENF is found to be much more than the conventional liquid

An arrangement in which nanofluids flows in separated channels outperforms the single channel through which the nanofluid is set to flow. In this arrangement a channel is placed underneath the rear surface of PV panel whereas, a separate channel is held above the front surface of the module. Upper channel nanofluid is made to achieve high liquid filter performance whereas the nanofluid flowing beneath the surface achieves higher thermal performance (working as a coolant). This technique achieved 8.5% higher electrical efficiency as

Integrating the heat receivers with the conventional PV system is found to elevate both electrical and thermal efficiencies. Several fluids such as water or nanofluids can be used in these receivers to remove heat so as to improve the efficiency of the system. Studies have proved that nanofluid based PV/T system outperforms conventional PV system and water-based PV/T system. Soltani et al. [30] used five different methods for PV cooling (natural cooling, forced air cooling,


cooling. Hussien et al. [31, 32] found enhancement in the thermal and electrical efficiency of

out at constant flow rate of 0.2L/s and nanoparticles concentration of 0.3%. Results showed the increase in thermal and electrical efficiency when temperature was decreased from 79.1 to 42°C. Thermal and electrical efficiency of system enhanced up to 34.4% and 12.1% respectively

nanoparticle in 50% water and 50% EG solutions



/*water* nanofluid as a coolant. Experimentation was carried

nanofluid is prepared by dispersing Fe<sup>3</sup>

optical filter.

40 Microfluidics and Nanofluidics

water cooling, *SiO*<sup>2</sup>

and *Fe*<sup>3</sup> *<sup>O</sup>*<sup>4</sup>

performance. They found that *SiO*<sup>2</sup>

PV/T system by application of *A l*

**Figure 4.** Maximum efficiency improvement by Nanofluid cooling compared to conventional PV.


**Authors** **Soltani et al.** 

—

Fe O3 4

SiO2

**Hussien** 

—

Al O2 3

Water

0.30wt.%

0.2 L/s

—

—

—

1000,

—

79.1 °C 42.2 °C

12.10%

34.40%

—

—

Application of Nanofluids for Thermal Management of Photovoltaic Modules: A Review

8%

—

—

—

Monocrystalline

**et al. [**32**]**

**Ebaid** 

—

Ti O2 3

Waterpolyethylene

0.1 wt%

5000 ml/

min

glycol

Water

—

5000 ml/

750,

—

16.58%

.61% Increase

—

—

—

compared to

conventional

Decrease

compare to

conventional

PV

PV

22.9%%

0.82% Increase

—

—

—

43

http://dx.doi.org/10.5772/intechopen.74967

compared to

conventional

Decrease

compare to

conventional

PV

PV

min

Monocry

stalline

**et al. [**33**]**

Water

0.5 wt.%

—

—

—

—

3.35%

—

increase

compared

to natural

cooling

Water

0.5 wt.%

—

—

—

—

3.13%

—

increase

compared

to natural

cooling

Water

—

—

Silicon

—

—

—

—

3.051%

—

increase

compared

to natural

cooling

Crystalline

PV Module

**[**30**]**

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2)**


**Al-Waeli et al.** 

SiC

Deionized

3 wt%

—

—

—

—

100.19%

24.1%

88.9%

—

42 Microfluidics and Nanofluidics

increase

increase

Increase

compared to

compared

compared

to conventional PV

to Water

Cooled PV

System

Water Cooled

PV System

Water

**[**16**]**

**Sardarabadi** 

No Cooling

—

ZnO

—

PCM +

—

—

Deionized

water

PCM + ZnO

Deionized

—

—

Water

Deionized

—

—

Water

Deionized

—

—

Water

—

—

—

845.42,

—

—

10°C

—

—

—

12.29%

Reduction

compared to

conventional

PV

6°C

—

—

—

13.17%

Reduction

compared to

conventional

PV

—

—

—

—

13.42%

—

—

—

12.23%

—

—

—

10.90%

Monocrystalline

**et al. [**19**]**

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2**

**)**


**Abd-Allah** 

Boehmite

Water

0.1 wt.%

200 ml/

—

—

21.6°C

21.87%

—

—

—

Reduction

Increase

compared

compared

to without

to without

cooling

cooling

min

(ALOOHxH O) 2

**et al. [**42**]** **Sathieshkumar** 

No cooling

—

CuTiO2

**Hasan et al. [**48**]** — SiC TiO2 SiO2 **Maadi et al. [**54**]** Al O2 3

TiO2 ZnO SiO2

Water

10 wt.%

30 kg/h

—

—

Water

10 wt.%

30 kg/h

—

—

Water

10 wt%

30 kg/h

—

—

Water

10 wt%

30 kg/h

Monocry

—

—

6.23% Increase

—

—

—

Application of Nanofluids for Thermal Management of Photovoltaic Modules: A Review

compared to

pure water

6.02% Increase

—

—

—

http://dx.doi.org/10.5772/intechopen.74967

compared to

pure water

6.88% Increase

—

—

—

compared to

pure water

5.77% Increase

—

—

—

45

compared to

pure water

stalline

Water

1 wt.%

0.167 kg/s

Water

1 wt.%

0.167 kg/s

Water

1 wt.%

0.167 kg/s

Water Water

—

0.167 kg/s

1000

30 °C

Decreased

11.40%

—

—

—

from 87–57°C

Decreased

12.75%

85%

97.75%

—

from 87–41°C

Decreased

12.30%

—

—

—

from 87–45°C

Decreased

11.80%

—

—

—

from

87–50 °C

Polycry

stalline

0.2 wt.%

0.02 kg/s

Water

—

0.02 kg/s

—

—

—

Monocry

–

—

11.31%

—

—

—

–

—

12.42%

18.43%

—

—

–

—

12.87%

19.50%

—

—

stalline

**et al. [**46**]**

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2)**


**Karami** 

ALOOH-XH

Water

0.01 wt.%

300 ml/

1000

25°C

Decrease

27.12% Increase

—

—

—

44 Microfluidics and Nanofluidics

from 62°C to

compared to

conventional

PV

32.5°C

min

Monocrystalline

O2

**and** 

**Rahimi** 

**[**34**]**

**Sardarabadi** 

No Cooling

—

SiO2 SiO2

**Sardarabadi** 

TiO2

Deionized

0.2 wt.%

30 kg/h

917

33.4 °C

11.48°C

6.54% Increase

—

—

—

compared to

conventional

Reduction as

compared to

Conventional

PV

PV

11.85°C

6.46% Increase

—

—

—

compared to

conventional

Reduction as

compared to

Conventional

PV

PV

11.03°C

6.36% Increase

—

—

—

compared to

conventional

Reduction as

compared to

Conventional

PV

PV

Monocry

stalline

Water

**and** 

**Passandideh.** 

**[**40**]**

ZnO

Al

O2 3

0.2 wt.%

30 kg/h

0.2 wt.%

30 kg/h

Water

3 wt.%

—

—

9.75% Increase

—

52.40%

14.02%

compared to

conventional

PV

Water

1 wt%

—

—

9.01% Increase

—

49.80%

13.85%

compared to

conventional

PV

Deionized

—

30L/h

Water

—

—

—

855,

33°C

—

—

8.2% Increase

35.60%

47.20%

13.54%

compared to

conventional

PV

—

—

11%,

11.53%

Monocry

stalline

**et al. [**37**]**

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2**

**)**


**J.J.**

**S.**

**Inyan. [**62]

—

—

CuO

Water Water

> **Al-Waeli et al.**

—

—

—

PCM + SiC

**Hamdan and** 

No Cooling

—

—

—

—

—

46.9 25.47 22.67 48.49 24.93 22.13

10.23%

—

—

—

http://dx.doi.org/10.5772/intechopen.74967

47

11.39%

—

—

—

12.57%

—

—

—

12.06%

—

—

—

11.20%

—

—

—

Application of Nanofluids for Thermal Management of Photovoltaic Modules: A Review

10.04%

—

—

—

**Kardasi [**65**]**

—

Al O2 3 No Cooling

—

CuO

> **Table 1.**

Effect of Nanofluids on PV/T System's performance.

Water

—

0.4 wt.%

—

—

0.6 wt.%

—

—

—

—

—

—

—

—

—

—

Water

—

0.175 kg/s —

PCM +

—

0.175 kg/s —

Water

Water

—

0.175 kg/s —

—

—

—

—

25°C

68.3°C 45.22°C 42.22°C 39.52°C

13.70%

72%

—

—

12.32%

50.50%

—

—

9.92%

35.40%

—

—

7.11%

—

—

—

**[**63**]**

0.05%

0.01 kg/s

With Glazing —

—

6.18%

30.43%

—

—

0.05%

0.01 kg/s

Without

—

—

7.62%

28.22%

—

—

Glazing

—

0.01 kg/s

With Glazing —

—

6.40%

21%

—

Water

—

0.01 kg/s

Without

—

—

8.77%

19.36%

—

—

Glazing

**Michael and** 

No Cooling

—

—

—

—

—

—

8.98%

—

—

—

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2)**


**Sahini at el.** 

—

Deionized

—

0.026 kg/s

Polycry

—

—

8.5% Increase

—

—

—

46 Microfluidics and Nanofluidics

compared

with

conventional

PV system

stalline PV

Module

Water

Silver with

Deionized

0.5 vol.%

0.026 kg/s

—

—

0.9% Increase

—

—

—

compared to

water cooled

system

Water

1 vol.% potassium

oleate

surfactant

**Sardarabadi** 

No Cooling

—

ZnO TiO2 Al2O3

Water

0.2 wt%

30 kg/h

Water

0.2 wt%

30 kg/h

Water

0.2 wt%

30 kg/h

Water

0.2 ey%

30 kg/h

—

—

—

917

34.42°C

—

11% decrease

13.41%

34.12%

47.53%

11.56%

compared to

conventional

PV

11.85%

13.59%

46.05%

59.64%

12.17%

decrease

compared to

conventional

PV

11.48%

13.63%

44.34%

57.97%

11.93%

Decrease

compared to

conventional

PV

11.03%

13.44%

36.66%

50.10%

11.88%

Decrease

compared to

conventional

PV

12.73%

—

12.73%

10.29%

Monocry

stalline

**et al. [**61**]**

**[**58**]**

**Nanoparticle**

**Base Fluid**

**Concentration**

**Flowrate**

**Module Type,** 

**Ambien** 

**Module** 

**Electrical** 

**Thermal** 

**Overall Efficiency**

**Efficiency**

**Energy**

**Exergy**

**Efficiency**

**Temp**

**Temp**

**Irradiation** 

**(W/m2**

**)**

**Table 1.** Effect of Nanofluids on PV/T System's performance. Gangadevi et al. [35] experimentally examined that the electrical, thermal and overall efficiency of PV module being cooled by Al2 O3 /water nanofluid got increased by 13%, 45% and 58% respectively as compared to water based and 1 wt% Al2 O3 nanofluid based cooling. Mustafa et al. [36] numerically tested the effect of mass flowrate and concentration of nanofluid (TiO2 /water) on the efficiency of PV/T system. As per the results, electrical and thermal efficiency of this system is linearly proportional to mass flowrate. Best results are obtained at low concentration of nanofluid.

effect of nanofluid concentration in spectral splitting filter based PV/T system. They observed that increasing the concentration of the nanofluid increased the nanofluid temperature and

Application of Nanofluids for Thermal Management of Photovoltaic Modules: A Review

The maximum overall efficiency of the system was found to be 75.93% and 80.58% when the ferrofluid concentration was increased from 1 wt% to 3 wt% respectively [37]. Khanjari et al. [41] observed that increasing volumetric concentration of the nanoparticle (from 1–5%) increased the heat transfer coefficient and thus the overall efficiency (from 1.33% to 11.54% for silver and 0.72% to 4.26% for alumina). Radwan et al. [20] observed efficiency escalation with increasing concentration. But some researchers witnessed contradictory results. Karami and Rahimi [34] examined that increasing concentration of nanoparticles reduces the efficiency because of agglomeration or clustering of the suspended particles. Abd-Allah, [42] found best

Cieslinski et al. [43] found no impact of nanoparticle concentration on the performance of the

<sup>2</sup> *O*<sup>3</sup>

compared to the distilled water and 3 wt% and 3 wt% did not change the thermal efficiency as compared to the distilled water thermal efficiency. Whereas, the overall efficiency of the

In order to obtain best results, there is always a need to determine the optimum concentration of nanoparticles in base fluid instead of using high volume fraction of nanofluid [43, 44]. However, instead of increasing the concentration of the same kind of nanoparticle, blending a different kind of nanoparticles can help improve the efficiency of PV module in a more

Sathieshkumar et al. [46] concluded that both electrical and thermal efficiency of the PV/T system increases with increasing flow rate but after a certain flowrate magnitude the efficiencies of the system start to decline. Overall energy efficiency is found to be higher in turbulent regime whereas overall exergy efficiency is higher in laminar regime [47]. Mustafa et al. [36]

the efficiency of PV/T system. As per the results, the electrical and thermal efficiency of this

Hasan et al. [48] observed that increasing the mass flowrate increased the cell efficiency linearly. As the mass flowrate increased from 0 to 1.666 kg/s the electrical efficiency of the cell

photovoltaic temperature decreased from 87° *C* to 41° *C* as the mass flowrate changed from 0

that temperature of the module decreased from 62° *C* to 32.5° *C* when the flow rate increased from zero to 300 ml/min. Khanjari et al. [41] observed that increase in inlet fluid velocity (from 0.05 m/s to 0.23 m/s) increase the first law (energy) efficiency but decreases the second law (exergy) efficiency (from 15.40% to 12.50% for silver). Lelea et al. [14] observed lower maximum module temperature for nanofluid based cooling as compared to water cooling at lower Re number. Whereas, at higher Re (Re > 1000) the maximum module temperature overlaps for

numerically tested the effect of mass flowrate and concentration of nanofluid (TiO2

system was found to be linearly proportional to mass flowrate.

nanofluid based cooling and water-based cooling of PV module.

increased from 8% to 16.5% at 500 W/m<sup>2</sup>

to 1.666 kg/s at 1000 W/m<sup>2</sup>

/*water* rather decreased the thermal efficiency

http://dx.doi.org/10.5772/intechopen.74967

49

solar irradiance in case of SiC-water nanofluid. Mean

solar irradiance in case of SiC. Karami and Rahimi. [34] observed

/water) on

system's electrical efficiency, but the thermal efficiency gets decreased in this way.

results at 0.1 wt% amongst (0.01, 0.1, 0.5 wt%).

PV/T system. They observed that 1 wt% of *A l*

system reached up to 80%.

efficient way [45].

**4.3. Flowrate**

Electrical, thermal and overall efficiencies of the various PV/T systems working with different nanofluids is expressed in the **Table 1**.

Efficiency enhancement of PVT systems being cooled by the nanofluids is due to the enhanced thermal conductivity of the nanofluids. Increase in thermal conductivity is dependent on concentration, size and type of the nanoparticle [4].
