Modular solar-thermal hybrid systems
Modular solar–thermal hybrid systems capture solar energy and store it as heat in insulated high-temperature thermal media such as molten salts or ceramic materials, then convert this stored heat into electricity on demand through heat engines. Thermal storage decouples energy collection from delivery, enabling dispatchable renewable output that can support evening peaks or periods of reduced solar generation.
Research by National Laboratory of the Rockies (NLR) demonstrates that high-temperature materials can retain heat with low losses over extended durations, providing a pathway for long-duration renewable supply in distributed settings. relatively rapid deployment for microgrids, industrial sites and grid-constrained digital infrastructure, offering an alternative form of renewable dispatchability where lithium-based batteries or fossil-fuel peaker backup would otherwise be used.[1,2]
Main outcomes of the solution
- Sustainability: Reduces reliance on electrochemical batteries by storing energy in thermal media, lowering exposure to critical-mineral supply risks and supporting greater use of solar resources without fossil-fuel backup.
- Reliability & Flexibility: Provides controllable renewable output and supports load during evening peaks or cloudy periods, while heat engines deliver stable, on-demand generation suitable for microgrids and industrial applications.
- System Resilience: Enhances resilience for remote or grid-constrained sites through thermally stable storage media and modular container units that offer redundancy, withstand repeated charge-discharge cycles and maintain performance across variable operating conditions.
Key deployment and scaling factors
- Identify locations with strong direct normal irradiance (DNI) where stored heat can reliably support evening peaks and deliver firm renewable output.
- Integrate the units into microgrid control systems so their output is coordinated with rooftop solar, thermal storage levels and any backup generators.
- Establish permitting processes that address thermal-storage safety, fire-protection rules and the electrical interconnection requirements for containerized systems.
- Create commercial models that deliver firm, low-carbon electricity to industrial sites and data centers, helping them avoid grid bottlenecks and long connection queues.
- Validate heat-engine performance and thermal-storage durability in real operating conditions to confirm stable, long-duration power output.
- Standardize the design and manufacturing of container units to speed up installation, simplify engineering work and enable consistent deployment across multiple sites.
- Work with distribution system operators (DSOs) and microgrid operators to manage local network constraints and ensure deployments support regional flexibility needs
Case Study
Exowatt (2024), USA
Exowatt is developing the P3, a modular solar–thermal hybrid system that uses an optical array to concentrate sunlight, stores the captured heat in a long-duration thermal battery and generates electricity on demand through a compact heat engine. Each 40-foot container is designed to operate as a standalone power module capable of extended-duration renewable generation. The system is engineered to avoid lithium and rare-earth materials, using thermally stable media and mechanical components intended to simplify maintenance and reduce supply-chain exposure.
Exowatt targets applications where consistent, local, low-carbon power is required—such as microgrids, industrial loads and data-centre campuses operating under grid constraints. Commercial deployments are expected to begin in 2025/2026, with early projects focused on demonstrating operational performance, integration with microgrid controls and the scalability of modular thermal storage. The P3 illustrates an emerging approach to dispatchable clean-energy supply using solar-thermal storage outside of conventional concentrated solar power configurations.[3]
References:
