Green Energy Systems: Design, Modelling, Synthesis and Applications

Green Energy Systems: Design, Modelling, Synthesis and Applications provides a comprehensive introduction to the design, modeling, optimization and application of predictable and alternative energy systems. With a strong focus on the fundamentals, the book provides an overview of the energy potential and conversion topology of green energy sources, the design and analysis of off grid solar and wind energy sources, and their application in effective energy management in rural communities. Sections address energy systems from solar, wind, biomass, and hybrid energy sources, and include discussions of power electronic circuit topologies for energy conversion in both off and on grid systems.

The second part of the book addresses energy harvesting at different scales, with a particular emphasis on micro energy harvesting for low power electronics like wearable devices. A wide range of applications are also discussed, alongside their challenges and solutions. Finally, case studies are presented on select topics to give readers deeper insights into the real-world applications discussed.

• Introduces the fundamental principles underlying green energy systems, their characterization, analysis, modelling, and evaluation
• Includes a wide range of applications of new functional materials for next-generation devices
• Provides supporting data and calculations alongside real-world case studies

• Language: English
• Publisher: Academic Press
• Release date: Dec 8, 2022
• ISBN: 9780323951098

Book preview

1: An investigation of a photovoltaic system under distinguished thermal environment conditions

Anurag Koushal ¹ , Yogesh K. Chauhan ² , Rupendra Kumar Pachauri ³ , Thanikanti Sudhakar Babu ⁴ , and Ali Q. Al-Shetwi ⁵       ¹ Electrical Engineering Department, School of Engineering, Gautam Buddha University, Greater Noida, Uttar Pradesh, India      ² Electrical Engineering Department, Kamla Nehru Institute of Technology, Sultanpur, Uttar Pradesh, India      ³ Electrical and Electronics Engineering Department, School of Engineering, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, India      ⁴ Department of Electrical and Electronics Engineering, Chaitanya Bharathi Institute of Technology (CBIT), Hyderabad, Telangana, India      ⁵ Electrical Engineering Department, Fahad Bin Sultan University, Tabuk, Saudi Arabia

Abstract

Due to their advantages over solar thermal and PV applications, over the last few decades, photovoltaic/thermal (PV/T) systems have been investigated in depth. Due to constant electrification and sectoral coupling, the demand for electricity in buildings and industry will continue to increase. A major proportion of electricity generated from renewable energy sources, such as wind, solar, biomass, and hydro, is essential to considerably reduce greenhouse gas emissions. The adverse problems of roof-mounted panels also apply to the supply of solar heating systems in that winds with high salt and abrasive sands both damage and reduce the efficiency of the units. Temperature variation not only affects the thermal performance of solar PV systems but also the electrical performance. In this chapter, a novel endeavor is made to extensively investigate a PV/T system under various conditions. The unique combination of water flow, reflector, and aerosol conditions is considered for thermal analysis. For this purpose, various experiments are performed on a 50−W polycrystalline PV panel. Based on the experimental results, polycrystalline PV performance is compared with different cases and in terms of monocrystalline PV panels of the same rating. This means that the thermal component is less than that of a solar thermal collector and can achieve an effective way of maximizing overall system efficiency and reliability.

Keywords

Photovoltaic system; Reflector; Thermal conditions; Water flow

1. Introduction

Nowadays, humans are highly dependent on technologies which enhance the power demand from commercial and domestic applications. Due to limited storage capacity of fossil fuels, renewable energy (RE) sources such as solar energy, wind energy, biofuel, etc., have been explored and made significant contributions to meeting the world's growing energy demands. Furthermore, solar energy has no environmental impact and produces clean energy, which is the main reason for its popularity compared to other RE sources [1]. A normal photovoltaic (PV) module can utilize 6%–20% of solar radiation incident on it, dependent upon the type of solar cells used, and also turn depends upon the prevalent climatic conditions [2].

In Ref. [3], the authors discussed the working performance of hybrid photovoltaic/thermal (PV/T) systems in both energetic and exegetics modes. It is taken into consideration that the energy is always destroyed whenever there is a fluctuation in temperature. Thus, the increase in entropy is proportional to the destruction of energy that has occurred. With the observations made the authors were able to show an increase in electric power and solar cell conversion efficiency. They also listed various factors which could limit the efficient performance of the solar PV module, such as (a) reflection of light from the surface of the module, (b) fluctuation in solar irradiation, (c) series resistance in current flow, (d) shading effect due to surface top electric contacts, and (e) a lack of the optimal operating temperature. In Ref. [4], the authors enhanced the efficiency of the solar PV system experimentally by inculcating a water flow effect over the glass and water mass basins heat capacity. Numerical calculations revealed the enhanced efficiency of a solar still. In Ref. [5], the authors carried out numerical investigations for a heat transfer and energy conversion process. They were able to show that, at low temperatures, there is an increase in thermal electrical generation for integrated PV systems per unit surface area. In Ref. [6], the authors calculated the effect of temperature variation and recorded the solar panel behavior. An analysis of solar module performance for temperature variation was made. The authors were able to show the improved performance of solar PV at low temperatures. The authors of Ref. [7] worked to improve the efficiency of solar PV systems using the floor heating system by passing a brine solution to cool the PV cells. This was done utilizing two different PV/T solutions for heat transfer analysis. In Ref. [8], the authors used halogen lamp radiation to calculate the effect of flow rate (volumetric) and the effect of angle of inclination on the performance of the solar PV system. In Ref. [9], the authors designed the PV/T system in such a way that the fluid flows on the top side of the PV panel in the fine gap between the solar cells of the PV panel. Using such a cooling method, the authors investigated the performance of the solar PV/T system. It was observed that there was an increment in the output power of the PV panel, leading to increased efficiency. In Refs. [10,11], the authors used two efficient strategies including a cooling methodology to increase the thermal electric performance of solar cells. Direct water cooling and cooling via a heated pipe were the methods used. This study was able to give the inverse relationship between PV cell temperature and terminal voltage. In Ref. [12], the authors conducted an experimental analysis of water flowing on top of the glass cover of a solar distillation system in a transient mode. The performance of the system was increased due to a significant difference between the temperatures of water and glass. In Ref. [13], the authors worked on the insulation effect on solar PV thermal collectors. The performance of a solar PV water collector in two modes, i.e., under partial and fully covered insulation, was discussed. An improvement in solar PV/T system efficiency involving impingement water jet cooling was discussed by the authors of Refs. [14,15]. Various modes such as radiation, electrical, optical, thermal, and jet cooling were included to understand the all-around PV system performance. The overall efficiency of the solar PV system was seen to obtain enhanced performance under the uniform cooling mode of working. In Ref. [16], a concentrated low-temperature fluid is routed to the rear of the panel through the heat exchanger. This heat was used for different domestic applications. Design parameters proposed in Ref. [17] were used for implementation. A review of PV/T hybrid solar technology is provided by the authors. Several theoretical and hardware models have been detailed. Data assessment and performance validation are carried out through implementation of beneficial technologies.

In Ref. [18], the authors performed an experimental analysis to show the effect of ambient temperature on PV system performance. The authors experimentally compared the correlation between temperature and efficiency for the correlation between wind speed and efficiency. In Ref. [19], the authors experimentally analyzed the seasonal change in the performance of a solar PV system. A comparative study of four seasons, namely monsoon, postmonsoon, winter, and summer, was carried out. The results showed that the lowest output was produced during the summer months (high ambient temperature) as compared to other months of operation. In Ref. [20], the authors provided a detailed review of the temperature dependency of PV efficiency along with its correlation and effect on the performance of a solar PV system throughout the world. In Ref. [21], the authors experimentally calculated the effect of dust on the performance of solar PV systems under partial shading during the operation. Experimentally derived results were compared to show the negative effect on solar PV efficiency.

The originality of this paper stems from the above-mentioned literature review, and aims to improve the performance of solar PV systems. Various experimental setups for thermal analysis are used to improve the working performance of both mono- and polycrystalline solar PV systems.

2. System description

A 50 W (polycrystalline) solar PV module is considered during this thermal experimental study. In this chapter, comprehensive analysis is carried out, such as (i) PV system performance at normal conditions, (ii) PV/T system performance with water flow, (iii) PV/T system performance with single-glazed water flow, (iv) PV/T system performance with reflector, (v) PV/T system performance with water flow and reflector, (vi) PV/T system performance with aerosol, (vii) PV/T system performance with combinations of aerosol and water flow, and (viii) PV/T system performance with aerosol, water flow, and reflector. The working performance is compared first within the system and then with the performance of the monocrystalline PV system. Fig. 1.1 depicts the experimental analysis schematic diagram. In this research, a comparative analysis of solar PV/T panels was undertaken, as well as other forms of thermal studies, in order to achieve optimum efficiency, voltage, current, and power of PV/T systems.

3. Modeling of PV system

For a PV cell, the total current I is calculated as the difference of photoelectric effect and diode current , as expressed in Eq. (1.1). Moreover, open circuit voltage is expressed in Eq. (1.2) as follows:

(1.1)

(1.2)

where, is diode saturation current (A) and stands for electron charge (1.6×10 −¹³ Coulombs). Moreover, is the Boltzmann's constant (1.38×10 −²³ J/K) and is used to show cell temperature . In addition, shows the cell voltage , represents the series resistance , and represents the ideality factor. An electrical equivalent circuit is shown in Fig. 1.2.

Figure 1.1  Schematic diagram of a PV/T system.

Figure 1.2  Simplified equivalent circuit model for a PV cell.

4. Experimental analysis

A comprehensive study was performed with the established hardware arrangement under distinguished environmental conditions as follows.

4.1. Air-type solar PV/thermal system

This consists of air channels cut into the backside of the PV module, with air pushed to flow through the channels into the specified system, either naturally or violently. It is less efficient in locations where the temperature is higher than 20°C.

4.2. Water-type solar PV/thermal system

This is made up of channels cut into the backside of the PV modules, through which water is forced to flow into the system. To boost the rate of heat transmission, forced water circulation is used. These are more expensive than air-type systems but have a better output efficiency.

4.3. Refrigerant-type PV/thermal system

This increases the extraction of heat with the use of refrigerants. The rear of the panel is equipped with direct evaporation coils to evaporate coolant while the module flows. To improve the cooling rate of solar PV modules, reusable coolants of a high species heat capacity are utilized. Coolants circulate a lot, giving the system an additional advantage.

4.4. Bifluid-type PV/thermal system

Two working liquids are used by this system to keep the system cool. Water and air are both utilized this time. The heat is absorbed by two different pathways simultaneously. One fluid flows through the system; the other fluid is still moving. The heat-absorbing capacity of the solar PV module is simultaneously increased through the use of two fluids.

4.5. Glazed solar PV/thermal system

On the top of the solar PV modules is the entire system included in a collector with a glass coating. The thermal efficiency of a glass-covered system using a conventional solar PV/T system is increased.

Although thermal efficiency has improved, it has not increased electrical efficiency.

4.6. Unglazed solar PV/thermal system

The whole top of the PV module in this system is composed of glass. Compared to a normal solar PV/T system, this system delivers increased electricity efficiency without a glass cover. While electric efficiency is increased, there is a shortage of thermal efficiency.

In this chapter, working on glazed, unglazed, and water solar PV/T systems is performed on various experimental setups for both monocrystalline and polycrystalline PV panels. All the schematic diagrams and experimental setups for the analysis of the PV/T system are shown in Figs. 1.3A–C.

5. Results and discussion

5.1. PV system performance at normal conditions

The experimental system is arranged to observe the performance under normal conditions. The electrical responses in terms of PV system power, voltage, and current outputs are measured for a 2-h study, which is summarized in Table 1.1.

Under the considered experimental conditions, a 50 W polycrystalline PV module with 156×156 mm size is considered. The temperature variation is taken from 31 to 44°C and the output voltage is dropped from 19.80 to 17.83 V, while the output power is dropped from 2.32650 to 2.03975 W. The performances in terms of voltage, power, and temperature of solar PV with respect to time are depicted in Figs. 1.4A and B.

5.2. PV/T system performance with only water flow

The experimental arrangement of the solar PV/T system is carried out with water flowing from the rear side of the panel. To maintain the flow of water properly, channels were made at the rear end of the panel, and water was made to flow through it. The electrical performance of the solar PV/T system is reported for 2h at 10-min successive time intervals. The measurement data are depicted in Table 1.2.

Due to the temperature increase from 30 to 44°C, the voltage output dropped from 19.92 to 18.14 V, while the output power dropped from 2.34060 to 2.07522 W. The performance observation is carried out in terms of power, voltage, and temperature of the PV/T model with respect to time, and is shown in Figs. 1.5A and B.

Figure 1.3  (A)–(C) Experimental setups for various types of thermal analysis.

Table 1.1

5.3. PV/T system performance with single-glazed water flow

The PV/T system is experimentally designed to function with water coming from the back of the panel, while the upper part of the panel was isolated by one clear glass. The thickness of the glass is 2mm. Channels are created at the back of the panel to ensure the correct water flow and water is drained from the panel. For 2 h, at 10−min intervals, are the voltage, power, and temperature of the PV/T system are measured, and measurement data are reported in