Energy Cabin SOLID

Renewable energy for SOLID headquarters in Graz

This demonstrator plant at SOLID headquarters in Graz provides renewable heating, cooling, and electricity to the office building.

Renewable supply of heating, cooling, and electricity

The plant consists of a 58 m² solar thermal collector field (40.6 kW) mounted on the canopy in front of the south-facing entrance. A container-sized wooden structure beneath the collectors houses the main components: circulation pumps, a 2,000 L hot water storage tank, a 16 kW absorption chiller, and a 200 L chilled water storage tank. The system supplies space heating in winter and solar-thermal-driven cooling in summer, ensuring reliable year-round thermal comfort with low operating costs.

In 2025, a 7.8 kWp photovoltaic system (35m²) with 12.7 kWh battery storage was added, allowing a large share of the electricity demand of both the building and the thermal plant to be covered on-site. The system can also be operated in island mode, maintaining heating, cooling, and electricity supply during grid outages.

Cooling with solar heat

Cooling is provided by solar thermal energy using an absorption chiller, which converts hot water into chilled water. Unlike conventional compression chillers, the system uses heat instead of electricity to generate cooling, significantly reducing electricity consumption and peak loads. This results in high efficiency and low electricity demand, especially during peak cooling periods.

A key advantage of solar cooling is the natural match between solar irradiance and cooling demand: high solar gains occur precisely when cooling demand is highest. This allows the building to be kept comfortably cool during summer with very low electricity consumption.

Demonstrator

The plant is realised as a compact, modular system integrating all main components in a container-sized structure, enabling flexible replication and simplified installation for similar applications.

Located directly in front of the SOLID office building, the system serves as a demonstrator and test bench for new developments, allowing continuous monitoring and optimisation under real operating conditions. The experience gained contributes to the further development and refinement of SOLID’s solar heating and cooling solutions for larger-scale applications.