From Forecasting to Capability: Cirata Strengthens Indonesia’s Renewable Energy Integration

A new variable renewable energy forecasting system at the Cirata Floating Solar PV Power Plant brings advanced forecasting technology into daily power system operations, supporting PLN in managing growing shares of solar and other variable renewable energy while strengthening Indonesia-Germany cooperation on the energy transition.
 
Cirata, 20 August 2026 – Indonesia took another step towards integrating higher shares of renewable energy into its electricity system with the inauguration of a new variable renewable energy (vRE) forecasting system at the Cirata Floating Solar PV Power Plant.

The inauguration took place during a visit by Reem Alabali-Radovan, Federal Minister for Economic Cooperation and Development of Germany, together with representatives of the Government of Indonesia, PT PLN (Persero), PT PLN Nusantara Power, the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG), the Government of the United Arab Emirates, German development cooperation, and other partners.

The German delegation also included Ralf Beste, German Ambassador to Indonesia, Timor-Leste and ASEAN; Carsten Schmitz-Hoffmann, Division Manager Latin America, Europe, North Africa / Middle East, Asia (LENA), GIZ; and Hans-Ludwig Bruns, Country Director of GIZ Indonesia & ASEAN.

The visit highlighted a central challenge for Indonesia’s energy transition: as more solar and other variable renewable energy enters the power system, expanding generation capacity must go hand in hand with strengthening the ability of grid operators to anticipate, manage and respond to fluctuations in renewable electricity generation. At Cirata, forecasting is helping turn this challenge into an operational capability.

Seeing Changes Earlier to Operate the Grid Better

Solar power generation naturally varies throughout the day depending on weather conditions. As the share of solar and wind in an electricity system increases, these variations become increasingly important for system operators.

Accurate forecasting provides operators with better information on how much renewable electricity is expected to be generated and when changes in generation may occur. This enables them to plan other generation, manage reserves and maintain the balance between electricity supply and demand more efficiently.

The vRE forecasting system at Cirata combines several forecasting approaches across different time horizons. Numerical weather prediction is used to support day-ahead forecasts, satellite-based information contributes to intraday forecasting, while sky-camera technology provides information for shorter-term forecasts.

These different sources are brought together in an operational dashboard, providing PLN with information that can support both power system planning and real-time operations. The objective is not to eliminate the inherent variability of renewable energy, but to make it more predictable and manageable.

By identifying changes in solar generation earlier, operators have more time to prepare and make informed dispatch and reserve decisions. Over time, this can contribute to more stable grid operations, more efficient use of reserves and reduced balancing requirements and costs.

From Technology to Operational Capability

The Cirata initiative goes beyond the installation of forecasting technology. A key objective of the pilot is to introduce an operational approach that can be integrated into PLN’s existing processes. This allows PLN to build practical experience in using renewable energy forecasts as part of day-to-day power system management.

This distinction is increasingly important as Indonesia expands renewable energy capacity. Technology can provide better information and new possibilities, but its long-term value depends on how effectively it becomes embedded in operational processes and institutional capabilities.

Cirata therefore serves not only as a demonstration of advanced forecasting tools, but also as an opportunity to strengthen the knowledge and experience required to operate a power system with growing shares of variable renewable energy.

The system draws on German technology and research expertise in renewable energy forecasting and energy meteorology. Overspeed GmbH & Co. KG, together with its partners, contributes experience from renewable energy forecasting systems covering approximately 200 GW of vRE capacity worldwide. The Energy Meteorology group of the German Aerospace Center (DLR) in Oldenburg contributes expertise in satellite- and sky-camera-based forecasting. The initiative also involves the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG), whose meteorological and climate data and expertise contribute to the broader ecosystem supporting renewable energy forecasting in Indonesia.

Through this cooperation, international experience in energy meteorology and forecasting is combined with PLN’s knowledge of Indonesia’s electricity system and operational requirements, alongside Indonesia’s meteorological and climate expertise, helping strengthen the capabilities needed to integrate increasing shares of variable renewable energy.

Supporting Indonesia’s Energy Transition

The Cirata forecasting initiative forms part of the broader German–Indonesian development cooperation in the energy sector, supported by the German Federal Ministry for Economic Cooperation and Development (BMZ) and implemented together with Indonesian partners.

Within the BMZ Development Cooperation Programme Energy, GIZ works with Indonesian partners to strengthen the political, regulatory and technical conditions required for a sustainable energy system.

One of these areas of cooperation is Renewable Energy to Grid (RE2Grid), which supports the planning and integration of variable renewable energy into Indonesia’s electricity system. The cooperation works with the Ministry of Energy and Mineral Resources (MEMR) and PLN on regulatory, technical and operational solutions that can enable the power system to accommodate increasing shares of renewable energy while maintaining reliability.

This contributes to Indonesia’s broader energy and climate objectives, including its long-term development vision towards Indonesia Emas 2045 and its commitment to achieving Net Zero Emissions by 2060 or sooner.

For a power system such as Java–Bali, the integration of higher shares of variable renewable energy requires more than the development of new renewable generation assets. Grid infrastructure, system planning, digitalisation, forecasting and operational capabilities must develop alongside generation capacity. The Cirata forecasting system demonstrates how these different elements can come together in practice.

Cirata as a Platform for International Cooperation

The 192 MWp Cirata Floating Solar PV Power Plant is itself an important milestone in Indonesia’s renewable energy development and one of the country’s flagship large-scale solar projects.

Its role is now expanding beyond renewable electricity generation. As a site for the implementation of advanced forecasting approaches, Cirata also provides a practical setting to explore how large-scale solar generation can be more effectively integrated into Indonesia’s electricity system.

The inauguration brought together Indonesian, German and international partners, reflecting the importance of collaboration in addressing the technical and investment challenges associated with the energy transition.

During the programme, Reem Alabali Radovan, Federal Minister for Economic Cooperation and Development of Germany, delivered a ministerial address highlighting the opportunities presented by Indonesia’s energy transition and the importance of continued cooperation.

The programme also featured remarks and presentations from Atena Falahti, Coordinator for Electricity Cooperation, Directorate General of Electricity, Ministry of Energy and Mineral Resources; Dwi Hartono, Director of Business Development & Commerce, PT PLN Nusantara Power; Denny Triyanto, Director of Risk Management, PT PLN (Persero); and Dr. Christoph Luerssen, Lead Power System Transformation, Energy Programme, GIZ Indonesia & ASEAN. Together, their contributions provided perspectives on Indonesia’s electricity system, the operation and development of the Cirata Floating Solar PV Power Plant, and the role of forecasting in supporting the integration of increasing shares of variable renewable energy.

The visit also provided an opportunity to discuss the future direction of Indonesia–Germany cooperation in the energy sector, particularly efforts to mobilise private investment in renewable energy and strengthen electricity grids to accommodate further renewable energy development.

Following the inauguration of the forecasting dashboard, the delegation visited the Cirata Floating Solar PV Power Plant by boat and met with staff to learn more about the facility, its operations and the role of forecasting in supporting the integration of solar electricity into the grid.

Building the Power System for the Next Phase of Renewable Energy

Indonesia’s renewable energy transition will increasingly depend not only on how much renewable capacity is installed, but also on how effectively the electricity system can accommodate it. Forecasting is one part of that transformation.

Better information on expected renewable generation can give system operators greater visibility of upcoming changes, allowing them to plan ahead, improve dispatch decisions and operate reserves more efficiently. Combined with stronger grids, appropriate regulatory frameworks, digital tools and skilled operators, these capabilities can help enable the secure integration of higher shares of renewable energy.

The Cirata pilot therefore represents more than the completion of a technology project. It demonstrates how cooperation can translate technology and research into practical capabilities for Indonesia’s electricity system.

By combining PLN’s operational experience with German expertise in renewable energy forecasting and energy meteorology, the initiative provides a foundation for learning that can inform the integration of renewable energy beyond Cirata.

As Indonesia continues to expand solar and other renewable energy sources, the experience gained at Cirata can contribute to a broader transformation of the power system—one in which renewable generation, grid development, digitalisation and operational capability advance together.

Ultimately, the value of forecasting lies in what it enables operators to do: see changes earlier, make better-informed decisions and keep the power system reliable as renewable energy continues to grow.

About the vRE Forecasting System at Cirata

The vRE forecasting system at the Cirata Floating Solar PV Power Plant combines numerical weather prediction, satellite data and sky-camera technology to provide solar generation forecasts across different time horizons, including day-ahead, intraday and shorter-term forecasting. The forecasts are integrated into an operational dashboard for PLN and can support power system planning and operations. The initiative is supported under the BMZ Development Cooperation Programme Energy and implemented by GIZ together with PLN and technology and research partners from Indonesia and Germany. The system forms part of broader German–Indonesian cooperation aimed at strengthening the conditions for integrating increasing shares of variable renewable energy into Indonesia’s electricity system while maintaining secure and reliable grid operations.

About German- Indonesian Cooperation on Renewable Energy Integration

Germany and Indonesia cooperate on the energy transition under the core area “Climate and energy, just transition.” Through technical cooperation, policy advisory and investment, German development cooperation supports Indonesia in expanding renewable energy, strengthening electricity grids and developing the institutional and technical capabilities needed for a sustainable energy system. Within this cooperation, the Energy Programme - GIZ Indonesia & ASEAN component works with Indonesian partners, including the Ministry of Energy and Mineral Resources and PLN, on solutions for the planning and integration of variable renewable energy into the power system. The cooperation contributes to Indonesia’s long-term sustainable development objectives and its ambition to achieve Net Zero Emissions by 2060 or sooner.