A storage heater or heat bank (Australia) is an electrical heater which stores thermal energy during the evening, or at night when base load electricity is available at lower cost, and releases the heat during the day as required.

Storage heater
Storage heater
Storage heater
Appendix B . Fire Protection Checklist
An electrical storage heater using the phase-change method of heat storage
Experimental research on a kind of novel high temperature phase change storage heater
Heat storage water heater
A solar water heater with a built-in latent heat storage
Performance of a collector/storage solar water heater
Integrated collector-storage solar water heater with extended storage unit
Performance of collector/storage solar water heaters: Arbitrary demand pattern
Assessment of energy efficiency in electric storage water heaters
Triangular built-in-storage solar water heater