Houshang Karimi

Step-by-Step Design of Large-Scale Photovoltaic Power Plants


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by local loads or is sold to electricity supply companies. The local loads may include commercial and/or industrial consumers.For the grid‐connected PV plant, the grid acts as an energy storage system and, therefore, there is no need to have battery storage. In the evenings, when the PV plant is unable to produce power, the required electricity can be purchased back from the power network [4].

      2 Stand‐alone PV Power PlantThe stand‐alone PV plants are used in the remote areas that have no access to the power grid. A stand‐alone PV plant operates independent of the grid, with part of the produced energy stored in energy storage systems such as batteries. A schematic diagram of a stand‐alone PV plant is shown in Figure 1.5. A stand‐alone PV plant includes PV modules, an inverter, batteries, and a charge controller. The inverter converts the direct current generated by the PV modules to the alternating current for AC applications. The PV plant can supply both the DC and AC loads [4].

      3 Direct‐coupled PV Power PlantIn a direct‐coupled PV plant, the PV array is connected directly to the load. The schematic diagram of a direct‐coupled PV plant is shown in Figure 1.6. The load can operate only when there is solar radiation and, therefore, the plant has limited applications. An application of this type of plant is water pumping, where the load operates as long as sunshine is available, and instead of storing the electrical energy, water is usually stored [5].Figure 1.4 Schematic diagram of a grid‐connected PV plant.Source: Modified from Vázquez and Vázquez [4].Figure 1.5 Schematic diagram of a stand‐alone PV plant.Source: Modified from Vázquez and Vázquez [4].Figure 1.6 Schematic diagram of a direct‐coupled PV plant.Source: Modified from Kalogirou [5].

      4 Hybrid‐connected PV Power PlantIn the hybrid‐connected PV plant, more than one type of generator is employed. In this type of power plant, one of the generators is a PV plant. The other generators can be wind turbine, diesel engine generator, or the utility grid. The diesel engine generator can also be a renewable source of electricity when the engine is fed with biofuels. The schematic diagram of a hybrid‐connected PV plant is shown in Figure 1.7. The plant can provide electricity for both DC and AC loads [5].

      5 Grid Energy StorageFigure 1.8 shows the schematic diagram of a grid energy storage PV power plant. The grid energy storage can be considered as a special model of hybrid‐connected plant. This type of power plant is used for countries where the guaranteed purchase tariff for electricity varies in peak, low, and medium load conditions. In the time periods when the guaranteed electricity purchase tariff is lower, the energy produced by the power plant is stored in batteries. When the tariff rate is higher at peak load conditions, the stored energy is injected into the grid to increase the annual revenue of the power plant.Figure 1.7 Schematic diagram of a hybrid‐connected PV plant.Source: Modified from Kalogirou [5].Figure 1.8 Schematic diagram of a grid energy storage PV plant.

Schematic illustration of different types of power based on their installation location.

      Source: Goodrich et al. [6]. Public Domain.

Schematic illustration of the classification of power plants in terms of their mounted on places. Schematic illustration of the classification of power plants in terms of size.

      Source: Rakhshani et al. [8]. Licensed Under CC BY 4.0.

      In the last two decades, significant numbers of PV power plants have been installed worldwide. The cumulative installed capacity of PV plants by the end of 2020 has reached about 751 GW. There are few reasons for investing in solar plants. The most important ones are:

      1 The economic incentives that some countries grant the investors by providing subsidies or purchasing PV power at high rates. Such incentives are included in the guaranteed electricity purchase tariff and are defined as a refund for the installed PV plants.

      2 The improvement in the efficiency of PV modules in recent years. Figure 1.12 shows the curves of the efficiency improvement of PV modules for monocrystals and polycrystals from 2010 to 2020 [9].

      3 The reduction in the costs of