Iran is located near the equator and southwest Asia, with an area of about 1,600,000 km². In some cities of Iran, there are about 300 sunny days. For example, the hottest city in the world is the city of Shahdad, in Kerman province [105,106]. Sunlight and stormy winds can be seen in all cities of Iran [103]. This part of the world has desirable conditions for the beneficial utilizing of solar energy. Iran has good opportunities for the spread of waterpower, and it is an ideal country for the use of solar energy [107,108]. A careful study revealed that the average global radiation of Iran is about 19.50 (MJ/m²)/day [109,110].

The amount of forthcoming global radiation (∼2000 (kWh/m²)/year) in Iran and other countries near the equator, such as the UAE and Saudi Arabia, is highest globally. Hosseini and Hosseini [111] studied a case study in Dehloran city located in the west of Iran to show how to utilize solar energy instead of gas and oil resources. Mostafaeipour et al. [112] studied the possibility of using solar energy in several regions of Iran. Their results showed that cities in central and southern regions could receive higher quantities of solar horizontal radiation. Southern Khorasan, Khuzestan, Yazd, and Kerman provinces catch considerable solar radiation values [113].

As shown in Figure 1, desirable cities with annual daily global radiation are located in the provinces of Kerman, Fars, Isfahan, and Yazd, in Iran. All large and small solar power plants are now located in these four provinces. Of course, other cities in Iran, such as Chaharmahal Bakhtiari, have an excellent ability to absorb solar energy. In recent years several solar power plants have been built in this province. The all-high fiord of the Yazd province is described by a high annual direct normal radiation of 2511 kWh/m² [114,115,116].

Iran has an extensive fossil source, and most of its power plants run on oil and gas. In recent years, environmental pollution has occurred in large cities like Tehran, Tabriz, and Isfahan. Also, with the expansion of industry and agriculture in Iran, the need for electricity is expanding. There is a shortage of electricity in the big cities of Iran now in the summer. Therefore, the Iranian government has been looking to establish solar power plants to provide electricity to their villages and cities in recent years. At present, the advantages of using clean energy against pollution and the high consumption and environmental costs of fossil fuels have led Iranians to use clean energy and fuel [117,118,119,120,121,122]. The renewable power plants’ geographical map is shown in Figure 2 [123].

The most significant number of solar power plants are installed in provinces of Kerman (with 4 to 10 MW solar power plants), Yazd (with 5 to 10 MW solar power plants), and Fars (with 7 to 10 MW solar power plants). In recent years, central cities of Iran such as Tehran (about 37.57 MW), Hamedan (about 31.4 MW), and Isfahan (about 13.45 MW) have also designed and built several solar power plants. The amount of power of solar power plants in the provinces of Iran is shown in Figure 3, where Yazd, Fars, and Kerman provinces with a capacity of 68.5, 98.8, and 54 MW, respectively, are the top provinces producing electricity from energy in Iran [124].

Renewable Energy & Energy Efficiency Organization (SATBA) reported that now 131 renewable power plants on a scale of MW with a total capacity of 876.69 MW have been put into operation. In addition, another 821 MW is under construction. Of these, there are 63 solar power plants with 433 MW and 20 wind power plants with about 308 MW (Figure 3). The rest of the power plants include small hydropower plants with a total capacity of 104.7 MW, biomass with a total capacity of 10.56 MW, and heat loss recovery from industrial processes with a total capacity of 13.6 MW [125].

As shown in Figure 4, about 178 million kWh of generated electricity is produced by renewable power plants in June 2021. As it turned out (Table 1), about 49% of electricity was generated by solar energy [126,127]. One of the critical points is that about 4277 thousand tons less CO₂ have been prevented. Moreover, a study of technical and economic assessment of the integrated solar combined cycle power plants in Iran was analyzed by Hosseini et al. [23].

Their study showed that increasing steam turbine capacity by 50% and 4% improvement in total efficiency are other advantages of Integrated Solar Combined System with 67 MW solar power plant. In addition, theoretical and technical potential evaluation of solar power generation in Iran was studied by Ghasemi et al. [128]. Their study was about Sistan and Baluchestan provinces, and their results showed that about 14% of the province is suitable for constructing solar power plants.

Electricity generated by solar farms in the cities of Iran is shown in Figure 4. The capacity of large solar farms in Iran is about 433 MW, and the provinces of Yazd, Fars, and Kerman are about 68.4, 57.6, and 46.7 MW of electricity produced by solar farms, respectively.

Kerman is the most important city in the southeast of Iran. Due to sunlight on more than 300 days of the year, Kerman province is located in the center of the golden trapezoid of the country’s solar energy, unique natural space. Furthrermore, adequate infrastructure, which is a significant advantage, can make this province a clean energy supply and attract foreign investors [129,130,131,132]. The use of solar plans to meet the needs of Iranian villagers and nomads is increasing. One of the small solar power plants in Kerman can be seen in Figure 5a [133].

According to the Renewable Energy & Energy Efficiency Organization (SATBA), a 10 MW power plant in Kerman province in Baft was connected to the grid [134]. The power plant is constructed in an area of 20 ha, using specialist and localized equipment by the private sector. It is estimated that by starting this solar plant, 9598 tons of environmental pollutants will be prevented, and 3060 cubic meters of water consumption will be reduced annually. In addition, the power plant will also save 3.95 million cubic meters of natural gas, annually, in Iran’s electricity production [135,136]. One of the largest solar power plants in Iran is located in Kerman province (Figure 5b). Mahan Solar Power Plant is designed to produce 20 megawatts per day. In total, 76,912 solar panels have been installed in this power plant, and about 21,000 bases have been hammered, and the amount of foreign investment in this project is US$27 million. Furthermore, this power plant will be converted to 100 megawatts in the future [137,138].

Kerman province has been considered one of Iran’s most proper provinces with the highest solar radiation. Eight solar power plants with a total capacity of 48.7 megawatts have been constructed and are running at the moment. In Kerman province, 926 solar rooftops with a capacity of 8228 kW have been installed [139]. In recent years, much research has been done to evaluate the possibility of electricity generation from solar energy in Kerman province [140,141,142]. For example, a comprehensive approach to design and improve a solar chimney power plant in Kerman Province was studied by Gholamalizadeh and Mansouri [143]. All large solar power plants in Kerman province are presented in Table 2.

Fars, a province located in the southwest of Iran, has an area of 122,400 km² [144]. The total capacity of renewable and clean power plants in Fars is 84.52 MW, which includes ten solar power plants with a cumulative capacity of 67.6 MW, a biomass power plant with a capacity of 1.065 MW, a wind power plant with a capacity of 0.66 MW, and two hydroelectric power plants with a capacity of 12.25 MW, as well as 331 small scale solar systems (roof) with a cumulative capacity of 2021 kW.

In Fars, there are several solar power plants with a capacity of 10 MW. Moreover, a list of high-power solar power plants in Fars is presented in Table 3. Renewable energy researchers in Fars are trying to show the people and the government the potential of converting solar energy into electricity [145,146,147].

In other provinces such as Isfahan, Tehran, Yazd, Hamedan (Figure 5c), and Khuzestan, a large solar power plant with a maximum capacity of 20 MW has been built. Table 4 lists several solar power plants in other cities of Iran [148].

Several other researchers across Iran have tried to cover the power consumption of industrial plants by technical and economic studies of various solar power plants [149,150]. For example, the techno-economic of PV systems capacity in Shiraz was studied by Yazdani and Yaghoubi [151]. In this analysis, a typical one MW solar plant was made in the software of PVsyst. The economic study displayed that enterprise in a PV system without any particular government help is economically advantageous, as the net present amount and Internal Rate of Return (IRR) were found to be US$1,367,499 and 17.09%, respectively.

A comprehensive study on the applications of different data-driven approaches in the performance modeling of solar units is introduced by Alhuyi Nazari et al. [152]. They are also in other studies on solar energy [153,154], reviews on the applications of multi-criteria decision-making approaches for power plant site selection.