A dispatchable latent heat solar thermophotovoltaic battery

Concentrated solar power coupled with thermal energy storage enables dispatchable solar electricity production, a key step towards the penetration of solar energy in the renewable energy mix. However, the high cost and moderate operating temperatures (∼565 °C) of current systems limit their competitiveness compared to photovoltaic–battery solutions. To overcome these limitations, this study introduces a conceptual solar-powered latent heat thermophotovoltaic battery coupled with beam-down concentrated solar optics for ultra-high temperature (∼1157 °C) energy storage and conversion. Designed with a modular architecture, the system allows for scalability and flexibility, enabling configurations that meet diverse energy demands. Operating in four distinct modes — charging, discharging, simultaneous charging/discharging, and storage — the system addresses critical challenges associated with modular solar thermal power systems. Minimizing lateral heat and solar-aperture re-emission losses and selecting thermophotovoltaic cells with band gaps tailored to the emitter temperature are key elements for an optimized system efficiency. Furthermore, the system’s dimensions significantly influence the optical, thermal and conversion performance, affecting radiation distribution, thermal insulation losses, and overall efficiency. A multi-physics model coupling optical, thermal and electric analyses reveals that, by minimizing the lateral thermal losses (<10 %) and maintaining a solar absorber efficiency over 65–70 %, the system can achieve round-trip efficiencies above 20 % for configurations with crucible heights between 0.48–0.72 m and thermophotovoltaic cell band gaps of 0.74 eV. These results demonstrate that the proposed system offers a compact, high-temperature, and dispatchable alternative to molten-salts, paving the way for next-generation solar energy storage and conversion.