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Scientific Reports volume 16, Article number: 7822 (2026) Cite this article
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In this study, the environmental, economic, and social impacts of two renewable energy projects with the same installed capacity—Cardakli Hydropower Plant and Ekinozu Solar Power Plant, both located in Elazig Province, Turkey—were compared using real-case data. The projects were evaluated based on investment costs, energy output, operational efficiency, carbon footprint, and water usage. Key numerical findings include: annual energy production of 38.6 GWh for HEPP and 26.28 GWh for SPP, initial investment costs of $19.5 million (HEPP) and $9.75 million (SPP), and payback periods of 9.22 years for HEPP vs. 3.72 years for SPP. In terms of resource usage, HEPP consumes 191,544 m³ water annually, while SPP requires only 8,672 m³. Carbon emission intensity was calculated as 9 gCO₂/kWh for HEPP and 98–167 gCO₂/kWh for SPP. Based on these results, the solar power project was found to be more advantageous in terms of investment return, environmental impact, and sustainability, although hydropower produces more energy annually. This comparative evaluation contributes to the literature by integrating real operational data into feasibility analysis and offering insight for renewable energy planning in emerging economies.
Energy resources are crucial to a nation’s social and economic development. The need for energy sources is rising due to factors including urbanization, industrialization, and population growth. For emerging nations to attain parity with developed nations and ensure sustainable growth, they must diversify their energy resources. It is crucial to have affordable, sustainable, clean, and dependable energy sources in order to address the current environmental issues brought on by global warming and climate change¹.
From the worldwide examination of the energy production rate in terms of used energy sources, it is observed that more than 60% of the production has been obtained from fossil sources². Gases emitted into the atmosphere as a result of consuming fossil fuels cause global warming and climate changes as a result of the greenhouse effect which they create as well as environmental pollution. It is estimated that energy-induced CO₂ gas emissions in 2011 were approximately 34 billion tonnes and this value will increase by 130% in 2050³.
Many countries participated in the first major global warming and climate change conference organized by the United Nations in Kyoto to reduce the release of carbon dioxide, which has a significant impact on global warming and climate change, and adopted Kyoto Protocol⁴. This conference declared the development of new mechanisms to reduce the total greenhouse gas emissions from industrial states by up to 5%. Both reducing greenhouse gas and creating sustainable energy; paves the way for the use of renewable energy sources. The renewal of renewable energy resources in a fast time, clean, safe, and sustainable, has increased the interest in these energetic resources⁵. In the last 50 years, the world’s consumption of renewable energy sources increased approximately 6 times and reached 5.9 TWh⁶.
Renewable energy consumption has gained a much faster acceleration over the last 10 years. The Kyoto Protocol is not the only reason why interest in renewable energy sources has increased so quickly in a short period of time. Many reasons such as sudden changes in oil prices, external dependence on the energy sources, and the environmental damages of carbon emissions have increased the interest in renewable energy sources. Renewable energy is a sustainable energy source that can be found in various forms in the world. Renewable energy sources are geothermal, hydroelectric energy, biomass energy, solar thermal technology, wind energy and photovoltaic energy systems which are increasing rapidly terms of the percent of the produced energy. The most widely used renewable energy sources in the world are solar energy, wind energy and hydropower sources⁷.
Approximately one third of renewable energy consumption is provided from hydroelectric power plants. The Hydraulic Energy board power of the countries, the amount of electricity generated from hydraulic energy and their share in world hydraulic energy production are given in Table 1. The total installed capacity of hydraulic energy of the world is 1.273,565 GW. In addition, a total of 4.163,310 TWh electrical energy was produced in hydraulic power plants. The power plants in these countries have welcomed 54.14% of the world’s hydroelectric power production⁷.
Although hydroelectric energy is the most consumed energy source, solar energy sources have increased approximately 25 times in the last 10 years thanks to its developing technology^6,7. The solar energy reaching the Earth’s surface every year is equivalent to 80 billion tons of oil (toe). This value is equal to approximately 10.000 times the energy consumed annually in the world. It is also more than the energy obtained from all reserves of coal, oil, natural gas and uranium sources. Approximately 25 Billion toe of 80 Billion toe energy hits the continents and the remaining 55 Billion toe energy hits the oceans⁸. Therefore, solar energy has come to the forefront among renewable energy sources in recent years. With this momentum, solar energy has the potential to be the most used energy source in advancing years⁶.
Table 2 shows the installed capacity of solar power of countries, the amount of electricity production from solar energy and their share in world solar energy production. The world’s total solar power installed capacity is 389,6 GW and the countries with the highest installed capacity are China, Japan, USA, Germany and Italy, respectively. In addition, these solar power plants generate a total of 328.71 TWh of electricity annually. The power plants in these countries have welcomed 69.81% of the world’s solar power generation⁷.
In this study, the social, economic, and environmental effects of hydroelectric power plants, which are the most widely used renewable energy sources in the current situation, and solar power plants which have the potential to have the greatest installed power in the next years have been compared. There are no real case studies in the literature investigating the environmental, economic, and social impacts of such power plants. Power plants compared in this study are located closely and have similar hydrological properties as they are in the same region. Further, these power plants have similar energy production capacities which provide to have more accurate and realistic results than those of the other studies. Recent studies in the Turkish context have emphasized the significance of stochastic modeling in LCOE estimation to capture uncertainties in market prices, technology costs, and energy yields, offering a more robust financial evaluation framework⁹.
Existing literature presents differing views on the comparative advantages of hydropower and solar energy systems. For example, studies such as Pacca et al.¹⁰) and IEA¹¹) emphasize hydropower’s superior long-term energy output and lower lifecycle carbon emissions, positioning it as one of the most environmentally efficient renewable energy options. Conversely, Sherwani et al.¹²) highlight solar power’s advantages in terms of modular scalability, ease of installation, and minimal water consumption—making it particularly suitable for arid or decentralized energy contexts.
From an economic standpoint, Streimikiene¹³) and more recently Güler & Yılmaz¹⁴) point out the varying investment risks and uncertainties associated with different renewable technologies, stressing the need for project-specific financial evaluations. These include metrics such as Levelized Cost of Electricity (LCOE), Net Present Value (NPV), and Internal Rate of Return (IRR), which can differ significantly depending on site conditions and support mechanisms.
Moreover, lifecycle-oriented environmental assessments, including water footprint and land use implications (Jin et al.¹⁵,; Peng et al.¹⁶,), are gaining increased attention as sustainability becomes a central criterion in project selection.
While many of these prior studies rely on theoretical modeling or generalized assumptions, the present study contributes to the literature by conducting a real-case, multi-criteria comparison based on two geographically close and equal-capacity renewable energy projects in Turkey. This approach provides empirical validation to existing theoretical frameworks and helps contextualize the practical challenges and advantages of hydropower and solar systems within an emerging market.
The scientific aim of this study is to compare the environmental, economic, and social impacts of two renewable energy systems—hydropower and solar power—through a real-case analysis of two projects with identical installed capacity in the same region.
The subject of the research is to evaluate Cardakli HEPP and Ekinozu SPP based on their financial feasibility, energy efficiency, and ecological footprint using empirical data, simulation outputs, and national market indicators.
This study extends existing research in the area of comparative renewable energy assessment by integrating real-world investment and operational parameters, particularly within the context of developing economies.
This study contributes to the existing literature in several main areas:
Holistic comparison of renewable energy systems.
By conducting a multi-criteria comparison (technical, economic, environmental, and social) between two real investment projects with identical installed capacity in the same region, our study goes beyond theoretical modeling and offers applied, region-specific insights.
Integration of real-case data into feasibility analysis.
The study uses actual site-specific hydrological and solar radiation data, installation details, and cost structures. This practical focus enhances the reliability and applicability of the findings for decision-makers.
Evaluation of renewable energy technologies in emerging economies.
Sustainability-focused metrics and lifecycle assessments.
Environmental factors such as water usage, lifecycle carbon emissions, and land use implications are incorporated, thereby broadening the traditional scope of economic evaluations.
The remainder of this paper is organized as follows: Sect. “Materıal and methods” presents the materials and methods used in the study, including the technical characteristics of the selected power plants and the modeling tools employed. Section “Result and discussion” discusses the results of the energy production simulations, economic analyses, and environmental assessments. Section “Conclusions” provides a comparative evaluation of the findings. Finally, Sect. 5 concludes the study and suggests directions for future research.
This chapter explains the general characteristics and technical features of the two selected power plant projects, as well as the simulation and calculation methods used for economic, energy, and environmental analysis.
The project site is located on the borders of Turkey’s eastern Anatolia region and within the boundaries of Elazig province. Cardakli HEPP Project was constructed between 516.000 and 521.000, 4.239.000- 4.241.000 geographical coordinates. It is located on the southern slope of Hazar Mountain and 45 km southwest of Sivrice district at 30 km southeast of Elazig province (Fig. 1).
The sole goal of the Cardakli HEPP project is electricity production. The Cardakli Weir, located at the crest elevation of the Ulucay River at 860.00 m, the Energy Water Intake Structure, the 2650.00-meter-long Transmission Channel, and the 1480-meter-long Transmission Tunnel comprise the transmission structure of the project. The facilities at the end of the transmission structure include a powerhouse unit and penstock that is 375.00 m long, as well as a forebay. The Cardakli Regulator, which is built on the Ulucay River, has a base elevation of 850 m. Water embossed by a weir is sent to a stilling basin. Following sedimentation in the stilling basin, the material is moved into a tunnel spanning 1480.00 m. From this point, a 2650.00 m long tube helps move it to the forebay. From here, it is transported via a 375.00 m long penstock to the above-ground power plant, which is situated at an elevation of 700.00 m. With a single suction tube, the power plant’s rectangular shaft will be positioned at a base of 695 m at a 15 MW turbine. A 3/0 AWG (Piegon) conductive cross-section power transmission line measuring 14 km in length is used to connect the produced electricity to the Karakaya substation. As a result, the interconnected system’s usage of the electricity is supplied¹⁷.
Locations of plants. Geographic locations of the Cardakli HEPP and Ekinozu SPP projects in Elazig Province, Turkey. Left: Satellite imagery generated by the author using Google Earth Pro (Version 7.3.6.9345). © Google Earth. Right: Administrative district boundaries of Elazig, annotated by the author for illustration purposes.
The average annual rainfall is 497.4 mm in Elazig, where the plant is installed. The highest rainfall occurs in April and the least rainfall occurs in August. The average annual temperature in Elazig is 12.9 °C. The highest temperature in the region is 42.2 °C in July and the lowest temperature is −19.4 °C in February.
The rainfall area of the Cardakli regulator is 207.0 km². The flow duration curve is given in Fig. 2.
Flow duration curve⁸. *Note: The FDC was developed based on 10 years (2008–2017) of monthly flow data obtained from DSI reports. Discharge values were ranked and plotted using the Weibull method.
The Flow Duration Curve (FDC) was constructed by ranking average daily flow values in descending order and calculating the exceedance probability for each discharge value. The exceedance probability was computed using the Weibull formula:
where P is the exceedance probability, m is the rank of the flow value, and n is the total number of flow data points. The resulting curve was plotted in Microsoft Excel.
The hydrological data used in the construction of the FDC was obtained from feasibility reports and archive datasets prepared by the General Directorate of State Hydraulic Works (DSI) for the Ulucay River basin. The dataset includes 10 years of monthly average flow measurements between 2008 and 2017.
Since the river is ungauged directly at the Cardakli HEPP site, the values were interpolated from upstream and nearby stations using catchment similarity and basin area adjustment methods, in accordance with standard practice in Turkish HEPP feasibility analysis¹⁷.
The main factors affecting the efficiency of solar energy in converting both heat energy and electrical energy are solar radiation intensity and geographic structure. The study area is the border region between the Eastern Anatolia Region and the Central Anatolia Region. As seen from the map, there is an annual production of electrical energy of more than 1650 kWh/kWp in regions within the Elazig province boundaries (Fig. 3).
Vegetation and landforms of Elazig-Kovancılar region paves the way for dissipationless use of direct sunlight due to the absence of any wooded areas and mountainous regions that may create a shadowing effect. The slope of the land where the solar power plant is installed is close to zero degrees. The area is far from residential areas, road railways, and airports.
Solar energy map of the study area. Figure 3. Location of the case study site in Elazig Province, Turkey. Irradiation map data adapted from GEPA (Ministry of Energy and Natural Resources), https://gepa.enerji.gov.tr/pages/23.aspx.
The primary cause of the low efficiency of solar cells in solar power plants is their high module temperatures, which are contingent upon the surrounding ambient temperature outside. When designing solar systems, the link between module temperature and system efficiency is crucial. The link between module temperature and system efficiency is linear. It is significant to remember that temperature readings are taken when the module’s nominal operating temperature, as determined by standard test settings, is exceeded. Nominal system efficiency decreases between 0.3% and 0.6% percentile values for every 1 °C increase in module temperature¹⁸.
PVGIS (The Joint Research Center Photovoltaic Geographic Information System) conducted by the European Commission provided radiation intensity data that indicates that in June, the solar energy values per unit area in the horizontal plane chosen for the Ekinozu Solar Power Plant project were 6.84 kWh/m². This figure was 1.71 kWh/m² in December. The annual average value was calculated as 4.35 kWh/m²-day. Radiation energy of Elazig province has values ranging between 5% and 20% according to months. This is higher than the average value of Turkey. In Fig. 4, total solar energy values and sunlight durations are given monthly with an average daily radiation energy falling on the unit area belonging to the Ekinozu Solar Power Plant project area. The values given here are the energy values of the photovoltaic modules falling on the inclined surface with an optimum tilt angle. In solar condensing systems, the operating performance of the systems may vary depending on the orbit of the sun. Therefore, based on some geographical data, the maximum energy value can be achieved in the year total by placing a certain fixed angle of the modules that will be used in solar collector systems. The angle of inclination of the photovoltaic module for the Elazig region was calculated as 31°. PVGIS of the European Commission contributed the radiation intensity data that served as the basis for the assessments made here. In many countries, the system performance data foreseen by means of modeling of the systems to be installed in local regions are provided through the data provided by this center.
Monthly distribution of the daily average energy values from a solar system with a 1 kWp installed power.
The quantity of energy that a 1kWp photovoltaic system may produce is calculated as an average 4.09 kWh/day/year using the obtained solar energy statistics. After analyzing daily average solar energy statistics by month, this number was discovered. These figures were computed using single-crystalline silicon solar cells with 14% system losses. Table 3 displays the monthly average of solar energy and photovoltaic energy values for a system with an installed power of 1 kWp. Additionally, assessments using PV-SOL software have been conducted based on the various module types, and the results have shown that a system with an installed power value of 1 kWp has an annual electricity generation potential of between 1663 and 1750 kWh/kWp.
This section presents and discusses the results of the energy production simulations, cost evaluations, and environmental impact assessments of the selected hydropower and solar power plants.
Water from the Ulucay River is diverted by a weir to a conveyance tunnel-canal and then to the turbines in a powerhouse 700 m above sea level. The turbines have a total installed power of 15 MW and an annual energy generation capacity of 38.6 GWh. The water was subsequently released into the Ulucay River, which is connected to the Karakaya dam’s reservoir. With a gross head of 162.08 m, the project is expected to have an 11 m³/s discharge flow. The annual rates of energy generation in the Ulucay River are shown in Fig. 5 as a bar plot.
Annual energy production values (GWh).
The HEPP was predicted to have an economic service life of 50 years. Who will use the generated electricity is a crucial topic concerning the project’s finances. The average value in the market for energy costs is 0.073 US dollars per kWh for realized energy projects. The total energy production capacity of Cardakli HEPP is planned as 38.6 GWh per year. Which leads to a calculated benefit of 2.817.800 $. The electricity tariff was determined according to the Turkish Renewable Energy Support Mechanism (YEKDEM). For the first 10 years of operation, hydro projects are guaranteed a price of 7.3 US cents/kWh, while solar projects receive 13.3 US cents/kWh. After this period, free market values are assumed under conservative projections.
The project is assessed twice, taking into account the following annual expenditures: (i) interest; and (ii) depreciation and amortization costs, which include operation and maintenance costs. Investments for the energy sector have interest and depreciation rates of around 9.5% over a 25-year economic life, translating to a factor of 0.09603. Generic Directorate of State Hydraulic Works (DSI) parameters were used to determine operation and maintenance costs as well as other criteria for each unit. As a consequence, 1.204.861 dollars are determined to be the project’s total annual cost. Regarding this cost ratio, the Cardakli HEPP’s income and expense ratio was calculated to be 2.08¹⁷.
The solar simulation is calculated with the PVsyst program considering the latest 50 annual data of the NASA National Solar Monitoring Agency and is given in Fig. 6.
Ekinozu SPP 1 MW simulation balances and main results.
Figure 7 provides the shade diagram for the Ekinozu SPP area. For the area, 21° is determined to be the ideal PV module angle.
Viewpoint of the PV-Field and the adjacent shaded area.
Anisotropic angle (21°, 0°), slope, and nominal power (1102 kW) were taken into account while calculating the energy generated by the system. The efficiency and losses of the inverters as well as the ground reflection coefficient (20%) where the modules are situated (albedo). Therefore, using Eq. (1), the energy produced by the system annually (Epy) is determined as follows:
In this case, Irr stands for yearly irradiation on the module surface. Losses are power losses, and Pnom is the system’s nominal power. A detailed graphical representation of the calculation of losses of the solar system is presented in Fig. 8.
Loss diagram over the whole year.
In a few years, the P50-P90 evaluation will likely be used to interpret simulation data. This approach has several concessions made. Different levels of efficiency are expressed by the P50 and P90, where the likelihood of any given year’s power generation being above this value is 50% and 90%, respectively. The annual meteo statistics vary by approximately 3–4%. As a result, there will be significantly more variation in monthly data from year to year. As a result, creating a probability profile for each month may lead to fluctuations in the results. This is one of the acceptances; it is assumed that their yearly revenues will follow the Gauss distribution for the duration of the study period (several years). As a result, the P50-P90 estimate for monthly values is illogical.
The following is how the P90 is computed: It is a value that emerges from statistical computation and ought to be supported by trustworthy meteorological data (at least 20 years). The region’s probability distribution of energy production is provided in this manner. Figure 9 shows the region’s probability distribution for energy generation.
Probability distribution.
The Ekinozu SPP’s economic service life was pegged at 25 years. Who will use the electricity generated by the project is a critical concern considering its economics. Projects that have had energy realized have total energy costs entered as total energy 0.133 US$/kWh, which was the standard value in the market. The estimates lead to a total energy production target of 26.28 GWh annually. The final calculation results in a total energy benefit of $3.495.240 for the Ekinozu SPP.
Despite the fact that hydroelectricity is regarded as a renewable energy source, many people in many different countries are against these expenditures because of the effects they have on the environment. The destruction of wildlife habitats and migration routes, impact on local precipitation patterns, controlled water release into the river below the dam, forced emigration of residents of settlements below the dam reservoir, and other negative effects of hydroelectric power plants are among the most frequently mentioned. Despite these drawbacks, the most economical way to produce electricity today is through hydroelectric power generating.
Within the scope of the Paris Agreement and sustainable development goals, hydropower projects protect countries against the harmful effects of climate change (flooding and drought). When compared to other energy sources, hydroelectric power has the lowest greenhouse gas (GHG) emissions per kilowatt-hour¹⁹. A hydroelectric power plant’s average life cycle carbon equivalent density is 18.5 gCO₂-eq/kWh²⁰.
The environmental effects of solar energy, one of the most widely used renewable energy sources, are also widely acknowledged. Solar systems cannot be considered a zero-emission technology due to environmental impacts such as land use, air quality, water use, and potential noise/visual pollution.
A number of studies have examined how PV systems’ carbon emission characteristics affect them¹²., conducted a review of studies conducted on the life cycle carbon emission parameters of systems in various geographical regions. Key factors like manufacturing energy consumption, module efficiency, and solar insolation that affect the energy payback time and life cycle carbon emissions of PV systems were studied by Pacca and colleagues²¹¹⁶., looked at the life cycle carbon emissions and energy payback period of several PV system types. The greenhouse gases (GHG) emitted by the different energy sources are shown in Table 4.
Determine the plant’s annual electricity production: Multiplying the installed capacity by the plant capacity factor and then adding 7920 (the number of hours the power plant operates in a year) yields the estimated annual energy production (Eqs. 2 and 3).
Plant emissions are calculated by multiplying energy generation by the relevant emission coefficients (Eqs. 4 and 5). This yields the annual carbon dioxide emissions.
where (Eq. 6) is used to calculate Ek = CO₂ emissions per year of generation mode k:
where FCk is the annual fuel consumption of power plant k (1000 m³ of biogas or producer gas from biomass energy system); EFk is the emission factor of the fuel used in power plant k (Ton CO₂/TJ); and UF is the unit conversion factor = 4186 J/cal and 109. The following equations provide the weighted average emission intensity (Ei) (Eq. 7):
Table 5 displays the build margin estimation computation. According to calculations, the emission factors for solar and hydroenergy systems are all zero because there is no pollution of any kind due to the distant rural location. However, the emissions occurring during the production phase are given in Table 6.
Water consumption during production and recycling procedures in power plants is significantly higher than in normal operations. Minerals processing, extraction, purification, and chemical etching are among the manufacturing processes. Fully assessing water use is a crucial step in understanding water conservation strategies for renewable energy sources.
According to Jin et al. (2019)²³, the median water consumption across the full life cycle of electricity generation technologies varies significantly between sources. Hydropower systems exhibit a median consumption of approximately 4,961 L per megawatt-hour (L/MWh), while solar photovoltaic systems consume around 330 L/MWh. These values reflect not only operational water use, but also embedded water in the manufacturing and infrastructure development stages.
It can be concluded that solar systems rank among the foremost renewable energy technologies in terms of minimal water consumption, making them especially suitable for regions experiencing water scarcity or climate-related stress.
In order to evaluate the economic performance of the proposed renewable energy systems, several standard financial metrics were applied in this study. These include:
Initial Investment Cost (USD): Total upfront capital cost, calculated as Unit Cost × Installed Power (e.g., $1300/kW × 15 MW for HEPP).
Annual Yield (USD/year): Total annual revenue from electricity sales (Energy Output × Tariff).
Operating Costs (USD/year): Annual operation and maintenance expenses, based on national averages ($15–18/kW).
Payback Period (years): Defined as Initial Investment/Annual Net Cash Inflow.
Total Energy Revenue over project life (USD): Based on guaranteed tariffs and projected output.
Levelized Cost of Electricity (LCOE) (USD/kWh): Computed as Total Lifetime Cost/Total Energy Generated.
Each indicator was calculated based on real-world assumptions and aligned with current market practices in Turkey. The comparative results are presented in Table 7.
When comparing the electrical energy produced by renewable energy sources to other systems that generate electrical energy from fossil fuels, the levelized cost of electricity (LCOE) is the unit of measurement that is utilized (Eq. 8). The system installation cost, operation, maintenance, and financial ratios used by nation are all included in this cost computation. The ratio of the costs of the PV and hydropower plants to the total amount of electrical energy produced during this time is known as the “levelized cost of electricity,” or LCOE for short.
Initial project expenses, depreciation, yearly running costs, and residual value make up the four primary components of system life cost. Depending on the system size, system maintenance and operation expenses might range from $15 to $18 per kW annually in total system life costs. In addition to all of these cost considerations, the average system life cost may be calculated by multiplying the system’s initial installation cost by 1.4 when depreciation and financial components are taken into account. Since the annual rental price pricing of the land where the systems will be used is not certain, it is included in the 1.4 coefficient in the life cost calculations of the system.
In addition, the annual energy gain values to be obtained from 1 kWp installed photovoltaic power plant are evaluated as 1650 kWh and 1750 kWh. Likewise, 2570 kWh energy gain is obtained from 1 kW hydroelectric power plant. The system losses are estimated to be 20%, although the producers of solar modules have specified an efficiency loss rate of 10% over a 25-year period. Likewise, the losses occurred in the electromechanical equipment of the hydroelectric power plant are considered as 10% and the efficiency loss rate of the electromechanical equipment specified by the turbine manufacturers is evaluated as 10% over 50 years.
The investment cost includes all capital expenditures necessary to bring each power plant into operation, including EPC (engineering, procurement and construction), civil works, electromechanical equipment, grid integration, licensing and land acquisition. Based on contractor bids and past project data in Turkey, the unit investment cost was set at $1300/kW for HEPP and $650/kW for SPP.
The cost per unit watts of photovoltaic systems varies depending on the size of the systems. Since the Ekinozu power plant is a large power plant with a power of 15 MW, a cost of the plant has a cost of $650/kW (Table 7). As the unit costs of hydroelectric power plants vary depending on the geographical structure, transmission structure, and many variables, the cost of 15 MW Cardakli HEPP has cost $1300/kW. These calculations are given in normalized unit costs. The assumed economic life cycle used in financial projections is 50 years for the hydropower plant, and 25 years for the solar power plant, reflecting standard industry practice and technology-specific lifespans.
In this study, the most widely used hydroelectric power plants among the renewable energy sources with solar power plants which are used effectively in recent years and which have the potential to be the greatest installed power in the future are compared to the socioeconomic and environmental aspects. The results of this comparison can be listed as follows;
Solar power plants have very important advantages such as short construction time and easy construction. This leads to easier financing of the plant.
The initial investment costs of solar power plants are lower than those of hydroelectric power plants. This provides ease of financing for investors.
When a medium or large scale solar power plant is compared with a hydroelectric power plant of the same size, the operational period operation costs are lower in the solar power plant. Thanks to this, solar power plants appear to be a more profitable investment considering the current state guaranteed prices in Turkey.
According to the current energy market prices in Turkey, the state offers the first ten years of purchase guarantees for the electricity produced by both types of plants. The first ten-year guarantee price for hydroelectric power plants is 7.3 USD Cent/kWh, while the guarantee purchase price of the electricity generated by solar power plants is 13.3 USD Cent/kWh. As can be seen, the purchase prices of the state are almost double in solar power plants. Thanks to this high price of solar energy, it reduces the period of redemption of the large-scale solar power plant to a very attractive time for investors, such as 5–6 years, together with the financing activity. Although energy production in hydroelectric power plants is high on an annual basis, due to the low purchase price of the state, the amortization period of the investment is 8–9 years together with the financing cost.
The annual energy production of the selected hydroelectric power plant (HEPP) was 38.6 GWh, while the solar power plant (SPP) generated 26.28 GWh under similar capacity and regional conditions.
In terms of payback period, the solar power plant investment was found to be significantly more attractive, with a return period of 3.72 years, compared to 9.22 years for the hydropower project.
After the first ten years, which is the guarantee of the state purchase, the energy market price will be determined in large part by the growing use of solar power plants and their ability to provide electricity during hours when people need it most.
Many industrialized nations have altered their perspectives and approaches to hydroelectric power plants as a result of the uncertainty around water resources brought on by climate change and global warming. The faith in hydroelectric power plants was particularly affected by the decline in river flow rates. As a result, hydroelectric power facilities no longer possess the characteristics of dependable renewable energy. In contrast, the amount of sunny days and the decrease in precipitation will make solar power plants more strategically important in the near future.
Compared to a traditional power generating system, the environmental impact of a solar energy system on air quality and climate change is far lower. One benefit of PV systems that use self-cleaning techniques is that they use less water while cleaning. PV modules have very little visual or auditory impact, with the exception of installation.
It is an undeniable fact that solar power plants are easier to construct in terms of environmental impact, while large hydroelectric power plants cannot be built in every region due to the damages it may cause to ecological balance.
Since hydroelectric power plants are built on rivers, they can be built in the event of reconciliation with the locals and local authorities. Legal procedures and permits for the construction of hydroelectric power plants may take as long as 5–10 years in the pre-construction period. On the other hand, solar power plants can be installed on private land in as little as 1–2 years with fewer government procedures.
The quality of life and environmental factors suggest that environmental pollution (air, water, etc.) is closely related to rising energy consumption; at the moment, climate change brought on by extensive use of fossil fuels that release carbon dioxide emissions is turning into a global issue that will affect future generations. Air pollution is one aspect of environmental concerns. Recent studies show that some renewable energy systems also have high emission values. In terms of carbon emissions, hydroelectric energy was shown to be more beneficial than solar energy systems.
The environmental concerns caused by the energy sectors are not limited to air pollution. Another dimension of the environmental problem is water pollution and excessive water use. In this respect, it can be said that solar energy systems are more advantageous.
The total annual water consumption was calculated as 191,544 m³ for the hydroelectric plant and only 8,672 m³ for the solar plant, indicating a significant environmental advantage for solar energy in water-scarce regions.
As a result, it is seen that solar power plants are more advantageous when social, environmental, and economic aspects of both types of power plants are considered. In the near future, it will become the most basic renewable energy source of many countries.
The data that support the findings of this study are not publicly available, Since the Euphrates is a transboundary river, data cannot be shared due to international politics. However, are available from the corresponding author on reasonable request.
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The author declares that no funds, grants, or other support were received during the preparation of this manuscript.
Department of Civil Engineering, Dogus University – Dudullu Campus, Istanbul, Turkey
Ayca Aytac
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Aytac, A. Environmental and socio-economic impact comparison of solar and hydroelectric systems. Sci Rep 16, 7822 (2026). https://doi.org/10.1038/s41598-025-10377-4
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Received: 10 June 2024
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Published: 15 February 2026
Version of record: 02 March 2026
DOI: https://doi.org/10.1038/s41598-025-10377-4
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