Pumped-storage hydroelectricity, compressed air energy storage, and flywheel energy storage are all types of solar energy storage technologies.

Battery energy storage is the most common type of solar energy storage technology.

Pumped-storage hydroelectricity works by pumping water from a lower reservoir to a higher reservoir when there is excess solar energy, and then releasing the water from the higher reservoir to the lower reservoir when there is a demand for electricity.

The efficiency of pumped-storage hydroelectricity is typically between 80% and 90%.

Compressed air energy storage works by compressing air and storing it in an underground cavern when there is excess solar energy, and then releasing the air from the cavern and using it to drive a turbine when there is a demand for electricity.

The efficiency of compressed air energy storage is typically between 70% and 80%.

Flywheel energy storage works by spinning a flywheel up to a high speed when there is excess solar energy, and then connecting the flywheel to a generator when there is a demand for electricity, and the generator converts the flywheel's kinetic energy into electricity.

The efficiency of flywheel energy storage is typically between 90% and 95%.

Solar energy storage technologies can help to integrate solar energy into the grid, reduce the cost of solar energy, and improve the reliability of solar energy.

Solar energy storage technologies can be expensive, have a limited lifespan, and be difficult to maintain.

The development of solar energy storage technologies is facing challenges related to cost, efficiency, and lifespan.

Promising research directions in solar energy storage technologies include new battery technologies, improved energy density, and longer lifespans.

Solar energy storage technologies are expected to play an increasingly important role in the grid, the cost of solar energy storage technologies is expected to continue to decline, and the efficiency of solar energy storage technologies is expected to continue to improve.

Solar thermal energy storage is not a type of solar energy storage technology.

Lithium-ion batteries are the most common type of battery used in solar energy storage systems.