Water spray cooling technique applied on a photovoltaic panel: The performance response

doi:10.1016/j.enconman.2015.10.079

Energy Conversion and Management

Volume 108, 15 January 2016, Pages 287-296

https://doi.org/10.1016/j.enconman.2015.10.079 Get rights and content

Highlights

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An experimental study was conducted on a monocrystalline photovoltaic panel (PV).
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A water spray cooling technique was implemented to determine PV panel response.
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The experimental results showed favorable cooling effect on the panel performance.
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A feasibility aspect of the water spray cooling technique was also proven.

Abstract

This paper presents an alternative cooling technique for photovoltaic (PV) panels that includes a water spray application over panel surfaces. An alternative cooling technique in the sense that both sides of the PV panel were cooled simultaneously, to investigate the total water spray cooling effect on the PV panel performance in circumstances of peak solar irradiation levels. A specific experimental setup was elaborated in detail and the developed cooling system for the PV panel was tested in a geographical location with a typical Mediterranean climate. The experimental result shows that it is possible to achieve a maximal total increase of 16.3% (effective 7.7%) in electric power output and a total increase of 14.1% (effective 5.9%) in PV panel electrical efficiency by using the proposed cooling technique in circumstances of peak solar irradiation. Furthermore, it was also possible to decrease panel temperature from an average 54 °C (non-cooled PV panel) to 24 °C in the case of simultaneous front and backside PV panel cooling. Economic feasibility was also determined for of the proposed water spray cooling technique, where the main advantage of the analyzed cooling technique is regarding the PV panel’s surface and its self-cleaning effect, which additionally acts as a booster to the average delivered electricity.

Introduction

Photovoltaic (PV) technology [1] is widely used today in different applications [2], [3], [4] but due to relatively high initial investments and low overall efficiency, the number of installed capacities is lower than expected. The second major problem of the commercial PV technology is its cleaning issue, i.e. dust impact and other particles accumulated on the front PV panel surface that can significantly reduce the amount of delivered electricity (in some cases reduction can go up to 30%). The previously mentioned issues (facts) can be overbridged through the improvement of existing market available technologies or through development of novel PV technologies. One possible option is to provide an increase in panel electrical efficiency along with solving its cleaning issue and aiming to develop feasible cooling techniques for the PV panel.

Even though novel PV technologies are currently under research and more efficient PV technologies are bound to be discovered (it is just matter of time), their expected market price will probably be too high for current market capabilities, so a wider market implementation can be questionable long term. A second possible option, besides the development of novel PV technologies, is to modify and upgrade existing available PV technologies.

It is well known that electrical efficiency in PV systems can be improved if panel temperature is reduced. This problem has been thoroughly studied in past years through the development of different cooling techniques. For the current market available PV technologies, electrical efficiency degradation is due to the rise of panel temperature which ranges from 0.25%/ °C up to 0.5%/° (depending from the specific PV technology used), so possible electrical efficiency improvement can be obtained with a proper cooling technique and keeping in mind that each cooling technique should have proven feasibility.

The objective of this paper was to develop an experimental setup and to investigate a water spray cooling technique, implemented simultaneously on the front and back side of a PV panel as well as other different water spray cooling circumstances to ensure gained result comparison and to offer an optimal cooling solution (regime). The proposed water spray cooling technique can potentially increase PV panel performance due to an evaporation and self-cleaning effect, which is also a great benefit in terms of improved feasibility in the long run.

Section snippets

Brief overview of the previous research findings regarding PV cooling techniques

The previous research work focused on different designs and experimental validation in cooling strategies for PV panels, to investigate their influence on overall efficiency and also to investigate specific energy losses in PV systems [5], [6]. In the majority of the proposed cooling techniques, water was used as a coolant and cooling was implemented on the front or backside of the PV panel. For example, in [7] authors investigated the effect of evaporative cooling implemented on PV panels and

The system configuration description

According to Fig. 1, an experimental configuration was assembled from a flat PV monocrystalline module of 50 W nominal maximal power with an effective surface of 0.31 m². The examined panel’s general characteristic is specified in Table 1. The panel was equipped with a system of nozzles mounted on the PV panel front and rear sides to ensure proper water spray distribution on both sides of the PV panel.

The panel was fixed under a specific angle of 17° (to obtain the highest electricity output for

General circumstances

The panel was tested on a geographical location with a Mediterranean climate (city of Split situated on the coastal side of Croatia) on a typical clear summer day where average temperatures of the surrounding air ranged from 27 °C and up to 30 °C. Measurements were provided from 11 am to 14 pm (period of highest solar irradiation levels during June). During the series of measurements, irradiation ranged from 810 W/m² to 850 W/m², in the already mentioned period of highest solar irradiation (specific

Conclusions

In this paper, a water spray cooling technique was proposed and experimentally tested on a monocrystalline photovoltaic panel for different cooling circumstances (regimes). The best cooling option turned out to be simultaneous cooling of front and backside PV panel surfaces. The gained experimental results (i.e. performance response) are summarized and briefly presented in Table 4, depending from different cooling regimes in the circumstances of highest solar irradiation levels.

In Table 4, we

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Water spray cooling technique applied on a photovoltaic panel: The performance response

Highlights

Abstract

Introduction

Section snippets

Brief overview of the previous research findings regarding PV cooling techniques

The system configuration description

General circumstances

Conclusions

Energy

Appl Energy

Energy

Energy

Energy Convers Manage

Energy

Renew Sustain Energy Rev

Ain Shams Eng J

Sol Energy Mater Sol Cells

Sol Energy

Energy Build

Appl Energy

Renewable Energy

Appl Energy

Renewable Energy

Appl Therm Eng

Exp Thermal Fluid Sci

Appl Therm Eng

Renewable Energy