Breadcrumbs
Türkiye can expand solar by 120 GW through rooftops
Türkiye’s rooftop solar potential is close to ten times its current installed solar capacity - enough to meet 45% of electricity consumption.
Available in: Türkçe
Highlights
120 GW
Technical potential of solar power on Türkiye’s rooftops
45%
The share of total electricity consumption in Türkiye that can be met from rooftops
$3.6 bn
Subsidies for residential power that can be reduced by rooftop solar
About
This study considers potential for expanding solar rooftop capacity in Türkiye, alongside potential benefits and routes towards policy implementation.
Analysis of high resolution satellite images is used to assess what solar panels can be installed on rooftops, outside the 11 provinces of Türkiye declared as disaster areas. By calculating the capacity and electricity production potential for each province, this then demonstrates the extent to which electricity consumption can be met through expanded rooftop solar. The analysis concludes with policy recommendations for Türkiye, taking into consideration global policies regarding rooftop solar energy, as well as the context of electricity tariff subsidies in Türkiye.
Executive summary
Rooftops offer a path to solar goals
Rooftop solar is an invaluable tool in expanding clean power. It does not require land and generates power at the point of consumption, making it more affordable and efficient. It will play a critical role in the economy by mitigating the EU carbon border levy’s impact on Turkish exports, and will underpin development efforts by providing people with the opportunity to produce their own electricity. The future of rooftop solar will also have an important impact on fiscal policies by reducing the need for subsidies in electricity tariffs.
Ufuk Alparslan Regional Lead
Rooftops are prioritised in energy transition policies across the world - and for good reason. Türkiye, which has ambitious solar targets, has a rooftop potential almost ten times its installed solar capacity. In addition to the current potential of roofs, tens of thousands of new buildings are being constructed every year in Türkiye with the rebuilding effort in the earthquake zone raising this figure even higher. Introducing rooftop solar obligations for new buildings and public buildings, and the tendering of suitable apartment building roof areas by municipalities can both help Türkiye achieve its energy targets and enable people to generate their own electricity cheaply.
Status of rooftop solar
Widespread benefits from rooftop solar power
Solar generation from rooftops is not only important in terms of energy and environmental policies; expansion can also benefit Türkiye in terms of industry, growth, development and fiscal policies.
There are obstacles to residential rooftop solar power installation other than the bureaucracy of the application process. According to the 2021 Population and Housing Census statistics of the Turkish Statistical Institute (TÜIK), 60.7% of households in Türkiye own the house in which they live. According to TÜİK’s 2021 Building and Housing Qualifications Survey, only 11.7% of households living in residences reside in single-story buildings.
Electricity generated on residential rooftops could help reduce the need for energy subsidies. According to official statements, national electricity tariffs in Türkiye are subject to subsidies of up to 50%. However, keeping electricity rates low does not reduce the cost of electricity — meeting that gap creates a burden on the treasury budget. Residences, where one quarter of the country’s electricity consumption occurs, receive the highest level of support. As more residences use electricity directly from solar panels, they will depend less on the subsidised power, therefore lessening the cost burden to the treasury.
A robust understanding of Türkiye’s rooftop solar power potential will serve as a guide for determining how much of the country’s planned future solar capacity can be installed on rooftops. Since rooftop solar power systems stand out as a clean energy alternative that can benefit all sectors, decisions taken on rooftop solar expansion will have an impact in industrial, residential and governmental areas. Understanding the potential for rooftop solar generation nationwide can help inform not only Türkiye’s energy and environmental policies, but also to navigate the impact and opportunities of CBAM, the development potential from prosumers and impacts on the treasury budget due to subsidies in electricity tariffs.
Rooftop potential
The path to solar targets is through rooftops
With a potential exceeding 120 GW and able to meet 45% of electricity consumption, rooftop solar will play a critical role in Türkiye’s energy transition.
According to the National Energy Plan published by the Ministry of Energy and Natural Resources at the end of 2022, Türkiye plans to increase its solar power capacity to 52.9 GW by 2035. The 12th Development Plan published in October 2023 foresees a solar capacity target of 30 GW to be achieved by the end of 2028. In other words, the aim is to install 3.8 GW of solar power plants every year between 2024 and 2028.
Although targets highlighting solar energy have been announced in the National Energy Plan and the 12th Development Plan, no information has been provided regarding the types of solar power plants that will contribute to these targets. It is therefore not clear what planned capacity will be installed on rooftops, land or water surfaces.
Türkiye’s technical potential of at least 120 GW of rooftop solar capacity indicates that rooftops will play an important role in achieving the country’s solar energy capacity targets. Given the absence of land requirements, the ability to generate electricity in the same place as consumption, and the potential for participation from individuals across all sectors, future goals should include the development of appropriate policies to help rooftops actively contribute to energy transition and economic development.
Global examples
Rooftop solar incentives are expanding worldwide
The need for clean and reliable electricity is driving countries to take advantage of their rooftops.
While rooftop solar installations have accelerated in many countries thanks to proactive policies as part of energy strategies, people have turned to rooftop solar as a solution in countries where energy supply security was hit by crises or war. For example, in Lebanon, where there have been cuts in fossil fuel imports due to the economic crisis since 2021, rooftop solar power installations grew from 14 MW in 2020 to 663 MW in 2022.
South Africa is another example where energy supply insecurity has driven consumers to rooftop solar. In the country, where more than 80% of the electricity production is sourced from coal, the number of days with at least one hour of power outage increased from 14 in 2018 to 181 in the first half of 2023. As self-consumption proved to be a feasible way of overcoming grid unreliability, rooftop solar capacity in South Africa increased more than fourfold from March 2022 to October 2023, surpassing 4.8 GW. This progress, which stemmed from consumer initiative, has started receiving support from the government through policies such as a tax deduction of one-fourth of the panel costs and loan guarantees.
In summary, a salient point in energy transition policies implemented worldwide is the prioritized utilisation of the solar potential on rooftops in electricity generation. When looking at the results of these policies and experiences in different countries, the electricity generated from rooftops is notable not only as a clean energy solution, but also in ensuring energy supply security.
Conclusion
Roofs stand out globally
With installation on roofs being given priority in many countries around the world, the share of roofs in new solar installations worldwide reached 50% as of 2022.
In Türkiye, 88.3% of the population lives in multi-story buildings. However, the current situation has hindered the development of electricity production on apartment rooftops due to shared rooftop ownership and obstacles posed by lengthy decision-making and application processes.
To promote widespread installation of solar power plants on apartment roofs, regional rooftop solar power programs can be designed by the responsible municipality or distribution company in the area. After determining the rooftop solar power potential of the apartments that choose to be part of this program, the total capacity in each region can be converted into a single rooftop solar power tender. While the electricity generated in excess of consumption from the solar power plants to be commissioned continues to be supplied to the grid, the income resulting from excess electricity production can be shared among the apartment residents in proportion to their legal shares on the roof, utilizing a virtual net metering system. The government can support such installations through tax deductions.
While incentives have made a significant contribution to the spread of rooftop electricity production around the world, the removal of obstacles can also have a stimulating effect. In Spain, for example, where the share of solar in electricity production was 11.5% as of 2022, the Solar Tax applied to solar power plants installed for self-consumption was one such obstacle. The removal of this tax in 2018 led to a rapid increase in the country’s solar capacity. In fact, the installed rooftop capacity doubled for two consecutive years and reached 3 GW in 2022. Despite being far behind in rooftop solar power potential, Türkiye’s policies could likewise lead to a rapid increase in rooftop solar installations.
Supporting Material
Methodology
Calculations of capacity potential
In the analysis, the publicly available Microsoft Building Footprints database, which contains more than 1 billion roof coordinates stored as polygons, was used to identify roofs in Türkiye. For this study, the May 2022 update, stored as a “Feature Collection” in the Google Earth Engine, was used. The dataset contains 18,058,257 polygons within the borders of Türkiye, including all kinds of structures with roofs.
More than one source was examined regarding the surface area a 1 kW solar power plant installed on the roof will occupy. According to a UK-based company that lists the most suitable solar panel options for homeowners and enables them to get price quotes, the required roof area is calculated as 6.4 m 2 per kW, assuming panels with less than 20% efficiency and with a capacity of 260 watts. According to a US-based website established to assist consumers in the solar energy sector, and an Australian service provider that lists solar panel suppliers to facilitate obtaining price quotes, the roof area required for 1 kW with panels of 330–400 watts and an efficiency of at least 20%, is from 4.1 to 5.6 m2. When ten random rooftop SPP projects completed in Türkiye in 2021-2022 were examined using satellite images, it was observed that the average area required for 1 kW of rooftop SPP capacity was 6.3 m2. Therefore, taking a conservative approach for the calculations, it was assumed that a 1 kW panel would cover an area of 6.4 m2.
The process of classifying roofs into three separate categories started with a training set including all three types identified in a satellite image containing only roofs for a selected province. In creating the training set, a sufficient number of randomly selected roof images were manually labeled according to the three roof types (flat empty/pitched empty/full). The decision to create a sufficient number of training sets was made using a validation set created completely independently of the training set. The validation set, selected from eight different regions of Türkiye, required the manual labelling of thousands of points in each region according to whether they were flat/pitched/full. Then, a visual classification algorithm designed on Google Earth Engine (GEE) was run to calculate accuracy rates in the validation set, and the training set was expanded and improved to maximize accuracy. The training set was created in Ankara, and the provinces covered by the validation set included Istanbul, Ankara, Izmir, Antalya, Konya, Erzurum, Trabzon and Şırnak. During validation, the final model achieved accuracy scores of 97% for empty pitched roofs, 83% for empty flat roofs, and 89% for full roofs.
Some corrections were applied to the roof areas following classification into three separate categories. The first correction was to reclassify areas with insufficient space for a panel as unsuitable roofs. Another adjustment was made for regions such as Antalya and Mersin, where greenhouse cultivation is common. For these regions, the coordinates of greenhouse roofs were manually identified and likewise classified as unsuitable.
Calculation of production forecasts
To determine the azimuth angles of pitched roofs in each province, roofs with an area between 150 and 500 m² in the Microsoft Building Footprints database were first filtered. This is because the majority of pitched roofs are found among roofs of this size. Assuming that the line dividing a roof into two sloping sides will run parallel to the long side of the roof, the angle between the long side of each rectangle obtained after filtering and the north-south axis was calculated and accepted as the azimuth angle of the roof. The calculated azimuth angles were then classified into categories based on directions, divided into eight equal parts of 45 degrees.
The maximum electricity production for the capacity potential of each district was calculated using the solar potential map published by Solargis (kWh/kWp). To achieve this, the Solargis potential map was uploaded to GEE and the pixel values were averaged for each district. The potential calculation provided by Solargis in this map was made based on the assumption of the production potential of an independent plant with optimum angles. It was thus used as a maximum production estimate. In the Solargis assumptions, inverter efficiency is 98%, loss due to dusting is 3.5%, DC-related loss is 2.3%, and AC-related loss is 0.9%. Correction factors applied to average district kWh/kWp potentials obtained from Solargis were calculated using the PVGIS solar energy production estimation model. For this purpose, tilt and azimuth angles for nine roof types in different parts of Türkiye were selected in PVGIS to calculate the degree to which the production estimate decreased compared to an independent solar power plant. These ratios were then used as correction factors in the analysis. As a final step, the capacity potential calculated for each district in GEE was multiplied by correction factors based on the average maximum production potential for the district and the roof category.
Subsidy calculations
In subsidy calculations for electricity tariffs, the active energy fee applied for low voltage – single rate second tier (above 8 kWh/day) in the Invoice-Based Tariff Tables published by the Energy Market Regulatory Authority (EPDK) was used. Monthly foreign exchange rates of the Central Bank of the Republic of Türkiye were used to convert tariff prices into US dollars. For the wholesale electricity market price, the prices reported in USD/MWh in the Day Ahead Market on the EPİAŞ Transparency Platform were used. The monthly subsidy amount was calculated by multiplying the monthly consumption of residential consumers published in EPDK’s monthly reports by the price difference between the two.
Acknowledgements
We would like to thank Ateş Uğurel (Solarvizyon) for reviewing the content of the text, Sam Hawkins and Matt Ewen for reviewing the methodology, Reynaldo Dizon for reviewing the data visualizations, and Eva Mbengue for reviewing the English translation of the text.
Image creditMikel Bilbao / Alamy Stock Photo