Molecular Solar Thermal: A Sunlight Battery for Heat Storage

A Science Magazine paper details Molecular Solar Thermal (MOST) energy storage that stores solar energy in UV-triggered molecular states (pyrimidone). It achieves about 1.65 MJ/kg energy density and can be liquid at room temperature, but heat release requires acidic conditions, complicating closed-loop use. The system exhibits self-discharge with a half-life up to roughly 481 days and supports only ~20 charge cycles, which limits practical cycling. While its energy density rivals Li‑ion batteries in theory, efficiency and cycling challenges mean it’s better suited for seasonal heat storage in sunny locations until further refinements improve viability.