Why is battery storage important for renewable energy?

Battery storage addresses intermittency of solar and wind by storing energy when generation exceeds demand and discharging when needed. Benefits include: time-shifting renewable generation to peak demand, providing backup power, smoothing variable output, reducing grid stress, enabling off-grid applications, and providing grid services (frequency regulation, voltage support). Common technologies are lithium-ion (high energy density, improving costs) and flow batteries (long duration). Storage enables higher renewable penetration and grid flexibility.