Battery Time-of-Use Arbitrage Value

Charge cheap off-peak and discharge dear on-peak, but the round trip loses ~15 percent, so the daily value is usable energy at the peak price minus the larger amount bought at off-peak to store it (daily = usable x peak - usable/RTE x offpeak). The catch every arbitrage pitch skips is that the peak has to beat off-peak by more than the round-trip loss (break-even = 1/RTE) just to break even, so a spread that looks like a tempting 1.56x nets almost nothing. The NREL round-trip framing; RTE is AC-to-AC, DoD is warranty-usable. A gross spread-value aid, not a financed payback.

usable_kwh = nameplate_kwh x dod; charge_kwh = usable_kwh / rte; daily_value = usable_kwh x peak_price - charge_kwh x offpeak_price; annual_value = daily_value x cycles_per_year; breakeven_ratio = 1 / rte.

The standard energy-arbitrage value (daily = usable x peak - (usable / RTE) x offpeak, usable = nameplate x DoD, break-even when peak > offpeak / RTE) and the NREL battery round-trip / degradation framing, by name; the relations are public.

The arbitrage-value arithmetic and the round-trip-efficiency relation are public; NREL storage cost/performance data is free at nrel.gov.

Estimate. AHJ and licensed professional govern.

Field names used by the API: nameplate_kwh, dod, rte, peak_price, offpeak_price, cycles_per_year, usable_kwh, charge_kwh, daily_value, annual_value, breakeven_ratio

• Arbitrage value daily = usable energy at the peak price minus the larger charge energy at the off-peak pricefirst principles
• Round-trip loss charge energy = usable / RTE; break-even requires peak > offpeak / RTE (AC-to-AC efficiency)NREL battery round-trip framing
• Usable energy usable = nameplate x depth of discharge (the warranty-usable fraction)manufacturer warranty