Grid Battery Storage Simulator

Grid Battery Storage

Battery capacity 40 MWh

Round-trip efficiency 90%

Solar fleet size 1.0×

Evening demand peak 1.0×

State of charge

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Flow

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Unmet demand today

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Cycles completed

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How it works

Solar output follows the sun and drops to zero at night, while electricity demand peaks in the evening — the "duck curve" mismatch that grid-scale batteries exist to fix. Whenever supply exceeds demand, the surplus charges the battery; whenever demand exceeds supply, the battery discharges to cover the gap. Every charge/discharge pass loses energy to internal resistance, split evenly across the round trip:

SOC += (P_surplus·dt·√RTE) / capacity     (charging)
SOC −= (P_deficit·dt) / (capacity·√RTE)   (discharging)
1 full cycle ≈ total throughput / (2·capacity)

Real grid-scale batteries run this exact loop: lithium-ion (mostly LFP) prices fell from $1,200/kWh in 2010 to about $139/kWh in 2023, and LFP packs are rated past 6,000 cycles — which is why round-trip efficiency (typically 85–95%) and cycle life, not raw capacity, decide how many years of daily arbitrage a battery bank can deliver before it needs replacing.

Battery capacity — total MWh the bank can hold; bigger banks absorb more midday surplus and cover more of the evening peak.
Round-trip efficiency — the fraction of stored energy actually returned; the rest is dissipated as heat inside the cells during charge and discharge.
Solar fleet size — scales the midday supply curve, changing how much surplus exists to store.
Evening demand peak — scales how sharp the evening ramp is, testing whether stored energy is enough to cover it.

Solar supply Demand Battery SOC Grid draw (unmet)

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