Any must match electricity production to consumption, both of which vary significantly over time. Energy derived from and varies with the weather on time scales ranging from less than a second to weeks or longer. is less flexible than , meaning it cannot easily match the variations in demand. Thus, without storage presents special challenges to .
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While the energy storage capacity of grid batteries is still small compared to the other major form of grid storage, with 200 GW power and 9000 GWh energy storage worldwide as of 2025 according to , the battery market is catching up very fast in terms of power generation capacity as price drops.
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