Battery Peak-Shaving Demand-Charge Savings
Sizes a battery to shave a commercial demand peak and prices it: the demand charge (often $10-30/kW on the single highest 15-minute reading of the month) times the shave, but the shave is energy-limited - a battery holds a given kW reduction only as long as its usable energy lasts (sustainable = usable / duration, actual = min(target, sustainable)). Shaving a 40 kW peak that persists three hours needs 120 kWh; a wide afternoon plateau demands far more storage per kW than a brief spike. The duration comes from an interval-meter load profile. A demand-savings estimate, not a metered bill.
Formula and source
usable_kwh = nameplate_kwh x dod; sustainable_kw = usable_kwh / event_duration_h; actual_shave_kw = min(target_shave_kw, sustainable_kw); annual_savings = actual_shave_kw x demand_per_kw_mo x 12; energy_limited = sustainable_kw < target_shave_kw.
The standard demand-charge peak-shaving method (sustainable shave = usable / duration, actual shave = min(target, sustainable), savings = actual shave x $/kW-month x 12), by name; the relations are public.
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