Storing Solar Energy As Ice For Air Conditioning

A DIY thermal energy storage system uses excess solar PV power to freeze water in a reservoir, storing cooling energy as ice. When needed, a glycol loop extracts the stored cold energy to cool air. Using R600 (n-butane) as refrigerant, the system leverages water's phase-change properties — 1 kWh per 10.8 kg or 92.8 kWh per cubic meter — making it more compact and cheaper than chemical batteries. A proof-of-concept prototype successfully cooled a car in two hours using a small PV array.