Photovoltaic Technology for Hot and Arid Environments by Aïssa Brahim;Tabet Nouar;

Author:Aïssa, Brahim;Tabet, Nouar;
Language: eng
Format: epub
Publisher: Institution of Engineering & Technology
Published: 2023-07-21T00:00:00+00:00

Chapter 6

Bifacial solar technology and module installation

Ahmer A.B. Baloch1, Brahim Aïssa2 and Nouar Tabet3

1 Research & Development Centre, Dubai Electricity and Water Authority (DEWA), United Arab Emirates

2 Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Qatar

3 Department of Applied Physics and Astronomy, College of Sciences, University of Sharjah, United Arab Emirates

6.1 Introduction

As the solar cells approach theoretical limits, the room for improvement is reducing due to diminishing returns on conversion efficiency. To push the state-of-the-art solar cells for their peak performance and overcome limiting factors, innovative approaches are required at each stage of the photovoltaic (PV) chain to decrease the efficiency gap and the levelized cost of electricity. Bifacial PV is one such technology that can harness incoming solar radiation from both front and rear sides to produce more energy yield than its counterpart traditional monofacial PV [1–4]. It has the potential to minimize the negative soiling effect and enhance energy generation under hot desert environment [5–9]. Vertical bifacial module facing east–west is one such configuration that can produce a broader power profile (i.e., relatively high power in the morning and afternoon), which may result in less peak shaving and soiling. Addition of bifacial systems into the existing electrical network can provide advantages including improved reliability, higher energy yield, and power consistency. The market share of bifacial modules is expected to reach 40% by 2028 [10]. This is due to the current interest of the international renewable agencies, industrial workshops, and bifacial PV pilot plant setups and standardization [10–12]. With this growing attention, there are few areas that need to be explored to prove its reliability in the field and minimize investment risk for large-scale deployment in hot and sunny climates.

The performance of solar cells is primarily determined by the properties of the absorbing material. However, the cell architecture also affects the cell characteristics. Silicon solar cells make 95% of the cell market today [10]. The silicon industry has achieved great progress in minimizing the energy losses in the device and maximizing the extraction of the photocurrent. The basic structure of the conventional cell is the back-surface field (BSF) cell. However, the passivated emitter rear contact (PERC) structure as shown in Figure 6.1(a) currently dominating along with other bifacial structures such as TOPCON (also known as passivated contact) solar cell and Silicon Heterojunction solar cell. Typically, in PERC structure, A thin layer of AlOx is added at the back surface to reduce the carrier recombination (passivation layer). PERC can be made bifacial, called PERC+, by replacing the aluminum back contact by a limited number of Al fingers as highlighted in Figure 6.1(b). This difference in bifacial design is at the cell level. Similar concept is applied for different device architecture to make them bifacial. However, to make true bifacial modules, transparent back sheets are also required at the rear while fabricating the module. Figure 6.1(c) and (d) shows the module consisting of a monofacial and bifacial solar cell placed in a sandwich between two layers of encapsulant and back sheet.

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