Research & Development

SOLID's R&D Department

Advancing Solar Thermal and Photovoltaic Solutions

The R&D department has been an integral part of SOLID for more than 25 years, laying the foundation for innovation and new developments in solar thermal and, more recently, photovoltaic applications. SOLID’s R&D experts are involved in national and international projects in collaboration with the world’s leading research and development organisations, key industry players and networks involved in the energy transition.

USP and main topics

The world’s largest test field for solar thermal collectors was built by SOLID – this solar district heating plant is used for both research and commercial purposes.

The commercially operated plant feeds solar energy into the district heating network of Graz, Austria’s second largest city. More than 10 different types of collectors are operated under real conditions. The test field makes it possible to evaluate the performance of the collectors, continuously improve their quality and increase their efficiency. A win-win situation for solar research and industry.

SOLID also offers its customers the monitoring of large solar thermal systems with storage tanks. A wide range of services is available, from individual data analysis by our solar experts to fully automated monitoring based on machine learning. SOLID also offers a full service package for the operation and maintenance of your system.

Selected R&D Projects


The TREASURE project is a pioneering initiative supported by the European Union through its HORIZON 2.5 – Climate, Energy and Mobility programme, with the main objectives of bridging the gap between research and practice to ensure robust, safe, cost-effective and sustainable large-scale thermal energy storage; developing safe and smart system integration concepts; and increasing the […]


HeatMineDH, aims to develop business models and investment plans for the integration of low quality heat sources into district heating networks. Through feasibility studies and practical investment plans, the project aims to help district heating companies and municipalities to meet the targets for efficient district heating in the next decade. The project is funded by […]

Harvest IT

The project HarvestIT was based on developing an open-source software for a comprehensive performance and yield analysis of large-scale solar thermal plants. SOLID Solar Energy Systems 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.


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 […]


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. It was the predecessor project of Harvest-IT.


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). In addition, numerical technologies are being developed to optimise the thermal, structural, system integration and economic suitability of materials, components and systems.


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.


This project aimed 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 […]


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.


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 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.


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. 


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 […]

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