A dual-cavity method and device for collecting and storing solar energy with metal oxide particles. Solar radiation irradiates into a light receiving cavity of a dual-cavity, heat-collecting reactor to heat a separating plate and preheat metal oxide particles. The preheated metal oxide particles then enter a reacting cavity. As temperature increases, the metal oxide particles reduce to release oxygen, which discharges through a gas outlet. Reduced metal oxide particles discharge through a particle outlet into a particle storage tank, and then into an oxidation heat exchanger to react with the discharged oxygen discharged to release and transfer stored chemical energy to a medium to be heated. The oxidized metal oxide particles are conveyed into a storage tank, and again enter into a particle inlet of the light receiving cavity. Ambient air controls the gas flow rate in the reactor and the reacting rate in exchanger.