The sun is a huge nuclear reactor where the fusion process of hydrogen atoms occurs continuously. It releases at its surface a power of about 3.8 × 10²⁶ W. The planet earth being at an average distance of 150 million km away from the sun, receives only 1.7 × 10¹⁷ W, which corresponds to an irradiance of 1,367 W/m². Part of this power is reflected back into space while the rest has to travel through the earth atmosphere where part of it is absorbed. About 60% reaches the surface of earth (10¹⁷ W). This average incident power is not uniformly distributed over the globe. The desert regions of North Africa and the Middle East known as the Sun Belt and the north of Chile have an average daily insolation exceeding 6 kWh/ m². Photovoltaics (PV) and concentrated solar power (CSP) are the main solar technologies that have been deployed at large scale in many regions of the world. However, the deployment of these technologies in the desert regions face some major challenges, among them the dusty atmosphere, high ambient temperatures, high UV component of the light spectrum, and high humidity in the regions close to the sea. These characteristics induce a reduction of the energy yield of the solar installations and a faster degradation over time which lead to an increased levelized cost of energy (LCOE). The impact of these environmental factors is discussed in detail in various chapters of this book.

In this introductory chapter, we review the basic characteristics of the solar light and the techniques to assess the insolation in a given place and harvest the solar energy.

The main aim of any energy conversion model is to establish upper limits for the conversion efficiency. The more detailed the thermodynamic model is, the more realistic upper bounds are obtained. However, the increase in the model's complexity is accompanied by more involved calculations. A generalized introduction to the fundamental principles of future solar energy systems, based on consistent physics is presented. In describing the various conversions, we make use of endo reversible thermodynamics - a subset of irreversible thermodynamics. In this way, readers are supplied with the information to enable them to calculate the explicit values for a broad class of processes. Throughout, general principles are illustrated using idealized models, and end-of-chapter Materials for Solar Cells are described and practical examples are merely presented so as to compare reality with theory.

The standard qualification testing from the International Electrotechnical Commission (IEC), such as, IEC 61215 (terrestrial photovoltaic (PV) modules - design qualification and type approval) provides a baseline for PV module to be installed in the field. However, module failure may occur during short- and long-term operation depending on the combined environmental parameters, e.g., in a desert climate with a typical high solar irradiance, high temperature and high soling rate. Studying the impact of the environmental conditions on the performance and degradation of PV system installed in desert climate is very important for the deployment of PV. Therefore, both indoor and outdoor testing of different PV technologies are essential to obtain PV system performance and financial data. From these data, potential energy generated from PV system lifetime will be estimated and the levelized cost of electricity (LCOE) can be calculated to compare the energy-generated from the different PV technologies. Several studies in the literature have shown the dependence of PV module performance on reliability. Degradation rate determine the loss in PV module and/or system performance expressed in percent per year (%/year). Other physical and statistical models have also been used to predict degradation rate for a specific type of failure mode.

This comprehensive review summarizes our experience with our field-measurements key findings and challenges in addressing soiling research obtained from our last 7 years of testing at the OTF. The PV soiling has been demonstrated to be a complex phenomenon, with high degree of freedom and various interplayed factors, including environmental ones, but also physico-chemical, structural, morphological, etc.

The soiling problem is far from being solved, and further research efforts are needed to understand and to tackle the issue. In the short term, commercially available PV cleaning machines and real-time scheduling of the cleaning based on atmospheric forecasts are promising approaches. In the long term, ASC may further reduce the cleaning frequency and cost. Encouraging results were obtained using different textured thin films (silica, metal oxides, and fluorides); further improvement and demonstration of the effectiveness and durability of the coatings will support their deployment in commercial PV projects. By learning lessons from the exposure of PV panels to the harsh environment of this region, Qatar has a unique opportunity to develop mitigation strategies that will benefit other arid regions of the GCC and the world. Finally, AS coating may serve as an efficient solution that complements the active cleaning process. Indeed, innovative solutions, cleaning concepts, and novel coatings are continually developed, addressing new functionalities, including self-healing, condensation run-off, and retrofit application.

In this chapter, we have first explained the development of the Australian PV market with a focus on local policies and the global market. At the moment of writing, Australia has among the highest distributed PV penetration on the world, resulting in unique challenges for its electricity grid. In 2019, PV is the cheapest way to produce electricity in most parts of Australia resulting in a boom in PV deployment including large utility-scale installations. The best solar resource is available in Australia's interior with a desert climate. However, the unique design of the Australian electricity grid in combination with the fact that most people are living in highly concentrated areas at its coast, means that most PV will be deployed closer to the coastal regions. Field-testing in the interior has revealed that recent PV installations show a degradation rate which is in line with their warranty despite the harsh climate conditions including a lack of rain to keep the PV systems clean. Although more research is needed in this area, this is comforting news as Australia is intensively investigating options to use the immense solar resource in its interior for the production of solar fuels, such as hydrogen and ammonia, to fuel the next "renewable" phase of resource export economy.