# Outdoor Testing to Compare the Technical and Economic Aspects of Single-and Dual-Fluid Photovoltaic/Thermal (PV/T) Systems

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## Abstract

**:**

_{2}emissions into the atmosphere.

## 1. Introduction

## 2. Experimental Details

#### 2.1. Methodology

- The PV module temperature and thermal and electrical gains are calculated based on hourly variations of solar radiation and dry bulb temperature. Summation of hourly data is used to obtain daily outputs, and subsequently the daily outputs are summed up for calculating the monthly gains.
- The proposed PV/T system is designed to be used for all aforementioned flow schemes such as air, water, and air plus water. During single-fluid operation, the second fluid is kept stagnant, with a zero mass flow rate.
- In the case of the dual-fluid heat exchanger, the optimal flow rate for each fluid is identified in such a way that the flow rate of any of the two fluids is varied over a range from 0 to 0.03 kg/s for water and 0 to 0.06 kg/s for air, while during this variation the second fluid is kept fixed at different flow regions such as laminar, transitional and turbulent.
- Exergy efficiency is calculated based on solar radiation and the thermal and electrical outputs.
- An economic analysis is performed based on energy and exergy performance of a PV/T system with dual and single fluid heat exchangers, and considering life cost analysis parameters such as initial cost, annual savings, and return on investment.

#### 2.2. Design and Operation Details

## 3. Analysis

#### 3.1. Energy Study

#### 3.2. Exergy Study

#### 3.3. Economic Study

_{2}mitigation over the system’s lifetime can be calculated as:

_{2}emission per kWh when generating electricity from coal [19]. Finally, the net CO

_{2}credit can be earned through carbon emission trading as follows [20].

_{2}is traded at 20 euro/ton [20].

## 4. Results and Discussion

_{2}emissions into the atmosphere. EPF, CO

_{2}mitigation, and carbon credits considering the life of the PV/T system with dual-fluid, water, and air heat exchangers for 20 and 25 years are given in Figure 12 and Figure 13. For the dual-fluid, water, and air type PV/T systems considering a 25 year lifetime, the highest values of EPF and carbon credits are 5.1 and 175.9; 4.4 and 142.4; and 3.8 and 127.7; respectively. It is observed that the dual-fluid PV/T system has the highest EPF and carbon credits. This can be interpreted as higher EPF and carbon credits being associated with additional thermal energy produced by the dual-fluid heat exchanger.

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## Nomenclature

$\mathrm{\u1e41}$ | mass flow rate (kg/s) |

$\mathrm{C}$ | specific heat (J/kg °C) |

$\mathrm{T}$ | temperature (°C) |

${\mathrm{A}}_{\mathrm{c}}$ | surface area (m^{2}) |

$\mathrm{P}$ | power (W) |

$\mathrm{G}$ | solar radiation (W/m^{2}) |

$\mathrm{NPV}$ | net present value |

$\mathrm{DCF}$ | discounted cash flow |

$\mathrm{CF}$ | cash flow |

${\mathrm{E}}_{\mathrm{s},\mathrm{y}}$ | annual electricity saved by PV/T system |

${\mathrm{E}}_{\mathrm{el}}$ | annual electricity saved by electrical load |

${\mathrm{E}}_{\mathrm{th}}$ | annual electricity saved by thermal load |

${\mathrm{D}}_{\mathrm{el}}$ | annual degradation of electrical performance |

${\mathrm{D}}_{\mathrm{th}}$ | annual degradation of thermal performance |

${\mathrm{COE}}_{\mathrm{I}}$ | domestic electricity cost |

${\mathrm{P}}_{\mathrm{ee}}$ | embodied energy (J) |

Greek | |

$\mathrm{\u0116}$ | exergy rate |

$\mathrm{\u014b}$ | efficiency |

${\mathrm{\u014b}}_{\mathrm{ex},\mathrm{th}}$ | exergy thermal efficiency |

${\mathrm{\u014b}}_{\mathrm{ex},\mathrm{el}}$ | exergy electrical efficiency |

${\mathrm{\u014b}}_{\mathrm{ex},\mathrm{PVT}}$ | total exergy efficiency by PV/T system |

$\mathrm{i}$ | inflation rate |

${\mathrm{i}}_{\mathrm{d}}$ | discount rate |

${\mathrm{i}}_{\mathrm{el}}$ | domestic electricity inflation rate |

Subscripts | |

$\mathrm{w}$ | circulating water |

$\mathrm{a}$ | circulating air |

in | Inlet |

o | Outlet |

$\infty $ | ambient air |

th | thermal |

el | electrical |

tot | Total |

max | maximum |

sc | short circuit |

oc | open circuit |

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**Figure 3.**Variations of overall efficiency of the dual-fluid PV/T system at variable air flow rate and fixed water flow rate.

**Figure 4.**Variations of overall efficiency of the dual-fluid PV/T system at variable water flow rate and fixed air flow rate.

**Figure 12.**Energy production factor (EPF) and discounted payback time (DPBT) for different PV/T systems at 20 and 25 years.

Cell Type Silicon | Mono-Crystalline |
---|---|

Module size | 1619 × 979 mm |

P_{max} | 260 W |

V_{max} | 31.6 V |

I_{max} | 8.23 A |

V_{oc} | 38.1 V |

I_{sc} | 9.27 A |

Aperture ratio | 48% (8 mm holes) |

Equipment | Uncertainty |
---|---|

Pyranometer | <±1.5% per year |

K-type Thermocouples | ±0.25–0.5 °C |

PT100 Ω | ±0.1 °C |

Flow meter | ±0.5% at full scale |

Multi-meter | ±0.1% |

Data logger | K-type: ±(0.05% of reading + 1.0 °C); PT100: ±0.8 °C |

Fitting of elements | ±0.1 °C |

Dual-Fluid PV/T System | Single-Fluid PV/T System | |
---|---|---|

Components | Price (USD) | Price (USD) |

PV module | 150 | 150 |

Heat exchanger | 530 | 290 for water type and 260 for air type |

Charge controller | 150 | 150 |

Digital flow meter | 120 | 120 |

Pump | 90 | - |

Air blower | 60 | - |

Pump or Air blower | - | 90 or 60 |

Water Tank (for water-type only) | 100 | 100 |

Piping or ducting | 90 | 60 for piping and 50 for ducting |

Installation | 150 | 150 |

Total | 1440 | 1100 for water type and 940 for air type |

Description | Values |
---|---|

Total investment | 1440 USD for dual-fluid, 1100 USD for water type, and 940 USD for air type |

Annual maintenance cost | 15 USD |

Cost of electricity [21] | 0.077 USD per kW/h |

Domestic electricity inflation rate | 2.0% |

Inflation rate [22] | 1.5% |

Discount rate [22] | 0.5% |

Annual degradation of PV & heat exchanger performances [1] | 1% and 1.5% |

Life of system | 25 |

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**MDPI and ACS Style**

Hussain, M.I.; Kim, J.-T.
Outdoor Testing to Compare the Technical and Economic Aspects of Single-and Dual-Fluid Photovoltaic/Thermal (PV/T) Systems. *Appl. Sci.* **2020**, *10*, 5641.
https://doi.org/10.3390/app10165641

**AMA Style**

Hussain MI, Kim J-T.
Outdoor Testing to Compare the Technical and Economic Aspects of Single-and Dual-Fluid Photovoltaic/Thermal (PV/T) Systems. *Applied Sciences*. 2020; 10(16):5641.
https://doi.org/10.3390/app10165641

**Chicago/Turabian Style**

Hussain, Muhammad Imtiaz, and Jun-Tae Kim.
2020. "Outdoor Testing to Compare the Technical and Economic Aspects of Single-and Dual-Fluid Photovoltaic/Thermal (PV/T) Systems" *Applied Sciences* 10, no. 16: 5641.
https://doi.org/10.3390/app10165641