Research & Development

Bringing solar energy technology ahead
Research & Development is an integral element of SOLID since more than 30 years.

SOLID Research & Development department

SOLID´s R&D department is the cornerstone for innovation and new developments for large scale solar thermal and recently also photovoltaic applications. 

The technical expertise of SOLID is acknowledged worldwide. Always being a step ahead, Research & Development is an integral element of SOLID since more than 30 years. SOLID´s R&D experts are participating in national and international projects together with the world’s leading Research & Development institutions, main industry players and networks dealing with energy transition.

USP and main R&D topics

The world’s largest test field for solar thermal collectors built by SOLID – this solar district heating plant was constructed for both, research and economic operation.

The commercially operating plant feeds solar energy into the district heating network to supply Graz, the 2nd biggest city of Austria. More than 10 different collector types are operating under real conditions. The test field provides the opportunity to evaluate the collector performance and offers the possibility to constantly improve quality and to increase efficiency in future collector developments. A win-win effect for solar research and industry.

SOLID also serves customers with data monitoring of large-scale solar thermal installations. We offer a wide range of services from individual data evaluation through our solar experts up to fully automated machine-learning-based supervision. SOLID also offers a full-service pack for operation & maintenance of your plant.


Selected R&D Projects




This project aims at improving the control of absorption heat pumping systems. They should be capable to explicitly consider and compensate the coupled and partly non-linear correlations between the different processes and process variables, all internal and external manipulated variables as well as the fluctuations of the external disturbances, e.g. the temperature of the incoming streams.




With METHODIQA, SOLID and other project partners AEE INTEC, Landesenergie Verein Steiermark and Cerebra pursued the goal of developing an innovative monitoring solution for renewable heating systems. METHODIQA enables an automated analysis and evaluation of current and historical operating data.





The project has developed novel materials and component technologies up to a technology readiness level between 4-5 (Laboratory testing of prototype component or process and laboratory testing of integrated system). Besides, numerical technologies are developed to optimize the thermal, structural, system integration and economic performance of materials, components and system.




This project aims on the basis of existing models and methods to develop a systematic approach, on the one hand to facilitate the planning of multi-sector energy networks (heat, electricity, gas),on the other hand to provide a techno-economically optimized operation strategy based on superordinate predictive control.




The IEA ECES TASK 39 aims at determining the aspects that are important in planning, design, decision-making and realising very large thermal energy storages for integration into district heating systems and for industrial processes, given the boundary conditions for different locations and different system configurations.




SHIP2FAIR aims to promote the integration of solar heat into industrial processes in the agri-food industry. To this end, SHIP2FAIR develops and demonstrates a set of tools and methodologies for the development of industrial solar thermal projects throughout their life cycle. 





SOLID was Operating Agent for the international solar heating and cooling IEA SHC TASK 55, which was dealing with large scale solar district heating (SDH) systems including heatpumps and seasonal heat storages technologies. In the follow-up Task IEA SHC TASK 68 SOLID has again a major role as Subtask Leader for Subtask B “Data Preparation and Utilization”.






This is precisely where the Austrian lead project „Thermaflex“ came in, which focused on increasing energy fl exibility and the resulting CO2 emission reductions in the district heating sector within the showcase region „GreenEnergyLab“. No fewer than 27 project partners were working on the identification, simulation-based planning, evaluation and selection as well as the implementation in combination with detailed monitoring and resulting optimisation of flexibility measures.




During the MeKuSo research project, the following goals were achieved: (1) in-situ methods were developed for estimating the actual energy output of large collector arrays, and (2) data were provided on the thermal performance of the deployed collectors under operating conditions in the field.




SPC refers to a model-based predictive control with an overall system approach, which also incorporates forecasting methods, for systems in the range of 50kW to 5MW. This flagship project demonstrates the benefits of smart networked control strategies for complex plants. The successful implementation on a real plant represents for SOLID a decisive step towards the future in a digitized world.






The project HarvestIT is based on developing an open-source software for a comprehensive performance and yield analysis of large-scale solar thermal plants. SOLID Solar Energy Systems GmbH is one of the industry partners of this project with the main objective to integrate the open-source software into their business processes and monitoring solutions. For further information have a look at the project webpage




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