Hybrid Geothermal–Solar Power at Zorlu Enerji’s Kızıldere 2 Plant Boosts Türkiye’s Renewable Capacity and Grid Reliability

Zorlu Enerji’s Kızıldere 2 hybrid plant marks a pivotal moment for geothermal‑plus‑solar in Türkiye, transforming an already strategic geothermal asset into a higher‑value, combined renewable facility that can deliver more flexible, resilient and investor‑attractive power to the grid.

Image: Geothermal workers onsite 

A new hybrid era at Kızıldere 2

Zorlu Enerji has moved Kızıldere 2 from a pure geothermal operation into a hybrid power plant by integrating a dedicated solar photovoltaic (PV) facility alongside the existing geothermal unit. The geothermal plant, located in the Sarayköy district of Denizli in western Türkiye, has long been a flagship 80 MW installation in the country’s renewable energy mix. By adding an approximately 8.5 MW solar PV plant on the same site, Zorlu increases the total installed capacity to around 88.7 MW, while using the same grid connection and site infrastructure.  

From a system perspective, the hybrid configuration allows Kızıldere 2 to blend stable geothermal baseload generation with daytime solar peaks, creating a more balanced production profile over a typical 24‑hour cycle. For grid operators and off‑takers, this mix of firm and variable renewable energy can improve reliability, reduce net load volatility, and support integration of higher renewable shares without compromising system stability.

Regulatory approval and license amendment

The hybrid shift at Kızıldere 2 is underpinned by regulatory changes to the plant’s generation license. Turkish authorities formally amended the license to categorise the plant as a “combined renewable electricity production facility,” recognising that electricity is now produced from both geothermal and solar sources within the same operating entity. This license amendment is critical for several reasons.  

First, it legally enables hybrid operation under Türkiye’s energy market framework, which has been gradually evolving to accommodate multi‑technology renewable plants. Second, it updates the recorded installed capacity to approximately 88.7 MW, reflecting the sum of geothermal and solar capabilities and allowing the plant to participate in market mechanisms and support schemes appropriate to its new scale. Third, it signals regulatory confidence in hybrid projects, which can support future investments by other developers seeking similar configurations.

Why Zorlu Enerji is betting on hybrid geothermal–solar

Zorlu Enerji’s decision to hybridise Kızıldere 2 is rooted in both technical and commercial rationales. Technically, geothermal plants provide continuous, dispatchable renewable energy with high capacity factors, often exceeding 90 per cent. Solar PV, by contrast, offers relatively low marginal operating costs and quick deployment but produces only when the sun shines. By combining the two at a single site, Zorlu can:  

- Use geothermal output to provide firm baseload power, ensuring the plant contributes stable generation during nights and cloudy periods.  

- Add solar PV to boost generation during daylight hours, increasing total output and revenue without major additional grid infrastructure.  

- Improve the utilisation of the grid connection capacity, as daytime peaks from solar can ride on the same transmission line that geothermal uses around the clock.  

Commercially, this hybrid approach allows Zorlu to extract more value from the Kızıldere 2 asset by layering additional renewable production onto an existing sunk investment. The company can sell incremental solar power during high‑price daytime periods while continuing to earn revenue from geothermal baseload. In markets where wholesale prices or feed‑in tariffs vary by time of day, this combined profile can enhance average realised prices per megawatt‑hour and improve project returns.

The strategic role of Kızıldere in Türkiye’s geothermal landscape

Kızıldere is already a cornerstone of Türkiye’s geothermal sector. The broader Kızıldere complex, encompassing Kızıldere 1, 2 and 3, is recognised as the country’s largest geothermal cluster, with total capacity in the range of 165 MW. Kızıldere 1 started as a smaller plant, while Kızıldere 2’s 80 MW commissioning represented a step change in scale and ambition. Kızıldere 3 then extended the complex further, consolidating Zorlu Enerji’s leadership in geothermal generation.  

With the hybridisation of Kızıldere 2, the complex shifts from being a symbol of geothermal development alone to a practical demonstration of integrated renewable operations. This is particularly important in Türkiye, which has rapidly grown its geothermal portfolio over the past decade and now ranks among the leading countries globally in installed geothermal capacity. Hybridisation showcases how established geothermal assets can be modernised and optimised for a new era of grid requirements, where flexibility, emissions reduction and cost control must be delivered simultaneously.

Technical synergies between geothermal and solar

Hybrid geothermal–solar systems like Kızıldere 2 benefit from several technical synergies that go beyond simple capacity addition. One key synergy is the complementarity of generation profiles. Geothermal output is essentially flat and predictable; solar output rises and falls with the sun. When combined, the overall plant can target a more “square” load profile that aligns better with demand curves, especially in regions where daytime consumption spikes due to cooling, industrial activity and commercial operations.  

Another synergy lies in shared infrastructure. Because geothermal plants require robust grid connections and ancillary systems, the marginal cost of adding solar PV can be lower when that infrastructure already exists. Interconnection, transformers, control rooms and some site facilities can be leveraged for the new asset, reducing capital expenditure per added megawatt. In addition, data acquisition, SCADA systems and control algorithms can be integrated so that plant operators monitor and optimise both geothermal and solar output in real time, adjusting operations to maximise efficiency and revenue while respecting grid constraints.

Financial and market implications for investors

For investors and analysts, Zorlu Enerji’s move at Kızıldere 2 carries several implications. First, it demonstrates that hybridisation can be a viable pathway to enhance returns on existing assets, rather than relying solely on greenfield development. By adding solar to a proven geothermal plant, Zorlu effectively upgrades the facility without the full risk profile of a new project, benefiting from established resource data, operating history and regulatory relationships.  

Second, hybrid plants can improve bankability by diversifying generation risk. Geothermal resource performance is highly stable once proven, but drilling and reservoir uncertainty can be significant during development. Solar output is well understood but depends on weather conditions and irradiance patterns. Combining the two reduces over‑reliance on a single resource and can make cash flows more resilient, which is attractive for lenders and equity investors.  

Third, hybridisation can align projects with evolving ESG and climate‑finance criteria. Multilateral banks, green funds and sustainability‑focused investors increasingly seek assets that deliver high renewable penetration, grid support and emissions reduction. A combined geothermal–solar plant ticks multiple boxes: it is low‑carbon, provides firm capacity, supports integration of variable renewables, and optimises land and infrastructure use.

Türkiye’s policy push for hybrid renewables

Türkiye’s energy policy has been gradually moving toward greater support for hybrid renewable plants. Regulations allowing multiple renewable technologies under a single license, and mechanisms for integrating complementary resources on the same site, are part of a broader effort to increase renewable penetration while maintaining grid reliability.  

Within this context, Kızıldere 2 serves as a proof‑of‑concept that hybrid plants can be successfully licensed, built and operated at commercial scale. As authorities refine rules on interconnection, metering, incentives and market participation for hybrid sites, the experience gained at Kızıldere 2 will likely inform future frameworks and encourage other operators to consider similar investments. For policymakers seeking to accelerate the energy transition without triggering instability or excessive costs, hybrid projects are an attractive tool that makes better use of existing assets and connections.

Operational benefits: flexibility, efficiency and grid support

Hybridising Kızıldere 2 brings tangible operational benefits. Flexibility is one of the most important. With both geothermal and solar at its disposal, the plant operator can adjust output patterns more dynamically. For instance, if solar generation is high and grid demand is moderate, geothermal can be slightly ramped back or used to supply auxiliary loads, reducing wear on equipment while still ensuring capacity availability. Conversely, during cloudy periods or peak evening demand, geothermal output can carry the plant.  

Efficiency gains can also arise from optimised maintenance scheduling. Solar arrays can be serviced during periods when geothermal is fully covering demand, minimising the need for plant‑wide outages. Likewise, geothermal equipment can undergo maintenance during times of strong solar production, maintaining overall site generation. From a grid‑support viewpoint, the combined plant can offer services such as voltage support, reactive power control and frequency regulation more robustly than single‑technology plants, especially when advanced inverters and control systems are deployed.

Positioning Zorlu Enerji as a regional innovator

By launching hybrid power production at Kızıldere 2, Zorlu Enerji positions itself as an innovator in the regional renewable market. The company already has a strong presence in geothermal, wind and solar, but hybridisation demonstrates a higher level of system thinking and portfolio optimisation. In an increasingly competitive landscape—both domestically and across neighbouring markets—being able to showcase successful hybrid projects can differentiate Zorlu from peers and support its reputation as a technically sophisticated and forward‑looking developer.  

This positioning matters for future tenders, partnerships and financing. Governments and utilities looking for reliable partners on complex renewable projects will gravitate toward developers that have proven they can manage multi‑technology plants, navigate regulatory transitions and deliver projects that align with long‑term energy strategies. Kızıldere 2 thus functions not only as a revenue‑generating asset but also as a strategic reference project in Zorlu’s corporate narrative.

Implications for global geothermal markets

Beyond Türkiye, the hybridisation of Kızıldere 2 has signal value for the global geothermal market. Many geothermal fields around the world are located in regions with strong solar resources—East Africa, the Andes, parts of Southeast Europe, and the western United States, among others. Yet, comparatively few projects have fully embraced hybrid geothermal–solar configurations at commercial scale.  

As more case studies like Kızıldere 2 emerge, developers and financiers may become more comfortable with the concept, seeing it not as a novel experiment but as a practical optimisation strategy. Hybridisation can become a standard pathway for extending the life and value of existing geothermal plants, enabling modest capacity upgrades, better grid services, and improved economics without new drilling campaigns. Over time, this could raise the profile of geothermal within the broader renewable mix, demonstrating that it is not only a baseload workhorse but also a flexible platform for integrated energy solutions.

Looking ahead: replication and scaling potential

The experience at Kızıldere 2 raises an important question: how quickly can similar hybrid models be replicated and scaled across Türkiye and other markets? For replication, key ingredients include favourable solar resources at geothermal sites, supportive regulation for multi‑technology licenses, and developers with sufficient technical and financial capacity to execute such integrations.  

In Türkiye, where geothermal clusters already exist in provinces like Denizli, Aydın and Manisa, there is significant potential to add solar at or near existing plants. Each successful hybrid project will strengthen the case for the next one, creating a virtuous cycle of learning and confidence. In other countries, especially those with nascent geothermal industries, integrating solar from the outset in new developments could become standard practice, designing plants as hybrid assets from day one rather than retrofits.  

For the global energy transition, these models illustrate a broader trend: as grids decarbonise, single‑technology assets are giving way to integrated, multi‑resource platforms. Kızıldere 2 stands at this frontier, showing that a mature geothermal plant can be successfully reimagined as a hybrid powerhouse that delivers more value, more flexibility and more resilience to the system it serves.

Source :Ceenergy