The development of renewable energies over the past two decades has become one of the main axes of energy policymaking in the world and in Iran. In this regard, each renewable source has its own specific characteristics, advantages, and limitations. But global and domestic statistics clearly show that solar energy, for numerous technical, economic, and executive reasons, has become the first option and the main axis of this transformation. In this article, we examine the position of solar energy in comparison with other renewable sources, including wind, hydropower, biomass, and geothermal.
The Global Picture: The Decisive Dominance of the Sun over New Capacities
According to the “Renewable Capacity Statistics 2026” report by the International Renewable Energy Agency (IRENA), the installed capacity of renewable energies in the world at the end of 2025 reached 5,149 gigawatts, an increase of 692 gigawatts compared to the previous year. In this regard, solar energy with a capacity of 2,392 gigawatts has claimed the largest share among all renewable sources and constitutes 46.5 percent of the total renewable capacity of the world. After that, hydropower with 1,296 gigawatts and wind with 1,291 gigawatts are in the next ranks.
But the statistics of existing installed capacity are only part of the picture. The more key point is the share of each source in the “newly added capacities” in 2025. In that year, solar energy alone claimed 511 gigawatts of the 692 gigawatts of new renewable capacity; that is, about three-quarters of the entire global growth. Wind energy with 159 gigawatts ranked second. In total, solar and wind constituted 96.8 percent of the total new renewable capacity. These statistics clearly show that other technologies such as hydropower, biomass, and geothermal have practically a negligible share in annual growth. Hydropower in 2025 grew by only 18.4 gigawatts, 96 percent of which was also related to China. Biomass added 3.4 gigawatts and geothermal only 0.3 gigawatts to the world’s capacity.
Structural Advantages of Solar Energy Compared to Other Sources
Why has solar energy gained such dominance over the growth of new capacities? The answer lies in a combination of structural advantages. First is “unrivaled spatial flexibility.” Unlike hydropower, which requires abundant rivers and specific topography, or wind energy, which depends on areas with continuous and relatively uniform wind, solar panels can be installed almost anywhere the sun shines. This feature has made the sun the “most democratic” energy source in the world. Second is the “speed of project implementation.” Constructing a solar power plant is much faster compared to a hydropower plant, which may take a decade or more, or wind farms, which require long-term wind measurement studies. Third is the “unprecedented reduction of costs.” The production cost of solar panels has seen a dramatic decrease in recent years, and this technology has become the cheapest source of new electricity generation in many parts of the world.
The limitations of each source also play an important role in this comparison. Hydropower faces the environmental challenges of building large dams and dependence on atmospheric precipitation. Wind faces the issue of wind intensity fluctuations, noise pollution, and impact on wildlife. Biomass depends on the sustainable supply of raw materials, and geothermal is limited to areas with specific geothermal potential. Solar energy also faces the challenge of intermittent production (night and cloudiness), but rapid advances in battery storage systems are gradually reducing this limitation.
Iran’s Situation: 90 Percent Dominance of the Sun over the Renewable Portfolio
Iran’s domestic picture also clearly shows the dominance of solar energy over other renewable sources. According to the latest statistics from the Ministry of Energy, the capacity of the country’s renewable and clean power plants has surpassed 6,014 megawatts. Of this amount, about 5,491 megawatts is allocated to solar power plants, which constitutes more than 90 percent of the country’s total renewable capacity. In comparison, the capacity of wind power plants is recorded at 371.6 megawatts, small hydropower at 102.9 megawatts, expansion turbines at 25.6 megawatts, and biomass power plants at 22.13 megawatts.
These statistics show that in Iran as well, as at the global level, solar energy has become the first option of investors and policymakers. Solar growth in Iran has accelerated especially in the past two years, and its capacity has increased from about 700 megawatts to more than 5,500 megawatts. This sevenfold growth has occurred while the growth of wind and hydropower capacity has been much slower. Currently, more than 1,300 medium- and large-scale solar projects and over 49,000 distributed solar systems have been put into operation across the country.
Iran’s natural advantage for solar energy is the high solar radiation in many regions of the country. Provinces such as Yazd, Kerman, and Sistan and Baluchestan enjoy the highest levels of solar radiation in the world, and this potential makes the development of solar power plants more economical and more accessible compared to other renewable sources that depend on specific geographical conditions.
The Challenge Ahead and the Necessity of Diversification
Despite the dominance of the sun, an important point should not be overlooked: diversification of the renewable energy portfolio is essential for grid stability. Solar energy, due to its intermittency, needs complementary sources for the stability of the electricity grid. Wind energy can play an important role during non-sunny hours and cold seasons when solar radiation decreases. Hydropower and biomass, as storable and dispatchable sources, can help balance the grid. Geothermal, with stable and 24-hour production, is a valuable option for areas with suitable potential.
According to domestic targets, the country’s renewable capacity is supposed to reach 12,000 megawatts by summer 1406. To realize this goal and beyond, it is necessary, alongside solar development, to pay attention to the balanced growth of other renewable sources. Currently, Iran’s wind energy with a capacity of less than 400 megawatts has a negligible share in the country’s clean energy portfolio, while the country’s wind potential in areas such as Manjil and Binalood is significant.
Conclusion: The Sun as the Backbone, Not the Only Option
Solar energy today is not only the largest renewable source in the world in terms of installed capacity, but alone accounts for about three-quarters of the annual growth of renewable capacity. This dominance is the result of a combination of natural, technical, and economic advantages that have made it an irreplaceable option for many countries, including Iran. However, the sustainable future of the energy grid requires a balanced approach: the sun as the backbone of the renewable portfolio, but with the support of complementary sources such as wind, hydropower, and storage systems. For leading companies such as Energy Gostar Hooran Paya, focusing on solar is a strategic and data-driven choice, but simultaneity with the development of other sources and storage technologies will guarantee the stability and long-term success of this path.
