A system and method for energy storage using phase change material.

A thermal energy storage system (300) with storage banks (302a-302f) containing different materials that undergo a phase change within different operation temperatures and therefore has a different melting point for storing heat. There is insulation (312) around each bank, and the banks can be enclosed within each other as Russian dolls or after each other as a line of banks. Thermal energy can be transported from an inlet (304) to heat exchangers (306) in each of the banks and to an outlet (308) via heat pipes in connection with a pump or another sort of prime mover. Heat can be moved from a lower temperature bank to a higher temperature bank. The banks can be switched in succession and/or in parallel or a selected bank can be chosen according to different criterions like the largest quantity of thermal energy. The storage system can be used in connection with a solar heat system, a boiler or a wood burning stove for heating or cooling of buildings.