Variable renewable energy

The 150 MW Andasol solar power station is a commercial parabolic trough solar thermal power plant, in Spain. The Andasol plant uses tanks of molten salt to store solar energy so that it can continue generating electricity even after sunset.
Grids with high penetration of renewable energy sources generally need more flexible generation rather than baseload generation

Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable (adjustable on demand) due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable energy sources, such as dammed hydroelectricity or bioenergy, or relatively constant sources, such as geothermal power.

The use of small amounts of intermittent power has little effect on grid operations. Using larger amounts of intermittent power may require upgrades or even a redesign of the grid infrastructure.

Options to absorb large shares of variable energy into the grid include using storage, improved interconnection between different variable sources to smooth out supply, using dispatchable energy sources such as hydroelectricity and having overcapacity, so that sufficient energy is produced even when weather is less favourable. More connections between the energy sector and the building, transport and industrial sectors may also help.