Battery Rate Arbitrage Payback
On a time-of-use rate plan, a battery can charge during cheap off-peak hours and discharge during expensive on-peak hours, pocketing the spread. This isolates that one specific value stream, separate from demand-charge savings or outage protection.
At your inputs, rate arbitrage with a battery pays back in 30.0 years and changes your annual cost by $400 a year.
| Net cost after confirmed incentives | $12,000 |
|---|---|
| Annual savings | $400 |
- This uses planning estimates you entered, not a contractor quote or guaranteed savings.
- Rate arbitrage value depends on your utility's actual time-of-use spread, which can change; weigh that uncertainty.
What this also tells you: If your annual savings are 20% higher or lower than entered, rate arbitrage payback would move from 37.5 years to 25.0 years.
This is a planning estimate based on your entries. It does not size equipment, determine electrical or building-code compliance, verify incentive eligibility, or replace a contractor quote or professional energy audit.
Why this decision comes up
Homeowners on a time-of-use rate plan often hear "arbitrage" pitched as a battery's main selling point, and it deserves its own isolated payback number rather than being bundled into a vaguer overall value claim.
How this is calculated
This is a standard payback calculation: battery net cost divided by annual savings from shifting usage between rate periods. Use your utility's actual time-of-use rates for an accurate estimate.
A worked example
With the defaults ($12,000 net cost, $1,800/year flat-rate baseline dropping to $1,400/year), the annual savings is $400 and payback lands at 30.0 years on arbitrage alone, a long horizon reflecting that at current battery prices, rate arbitrage by itself rarely justifies the cost without a bigger rate spread, demand-charge savings, or outage value added.
Common mistakes
A common mistake is assuming a large rate spread automatically means strong arbitrage value without checking your actual usage pattern against the rate schedule's specific peak and off-peak windows.
Limitations
This does not include demand-charge savings or outage protection value. See the related tools in this cluster to build a complete picture of a battery's total value.
Common questions
What rate spread makes arbitrage worthwhile?
The bigger the gap between your off-peak and on-peak rates, the more a battery can capture. A small spread produces modest arbitrage value regardless of battery size.
Is this the same as demand-charge savings?
No. Rate arbitrage is about the price difference between times of day; demand charges are a separate fee based on your peak power draw. See the demand-charge savings tool for that specific value stream.
Does battery efficiency loss affect this?
Yes, charging and discharging a battery loses some energy to inefficiency, which your entered annual savings figure should already account for if you have a realistic estimate.
Does my utility need to specifically allow battery arbitrage?
Most time-of-use plans allow it inherently, since you are simply shifting when you draw from the grid. Check for any specific restrictions or separate battery tariffs some utilities apply before assuming full flexibility.
Can arbitrage value change after I buy the battery?
Yes, utilities periodically revise time-of-use windows and rate spreads, which can improve or worsen arbitrage value after purchase. This tool reflects today's rates, not a forecast of future changes.