Backup Power Breakeven Electricity Rate
Rather than testing one system cost against one assumed rate, this works backward: given the backup system's cost and expected rate-based savings, what electricity rate makes it hit your target payback, compared directly against your actual rate.
At your inputs, the electricity rate that hits a 10-year payback is $0.300/kWh.
| Required electricity rate | $0.300/kWh |
|---|---|
| Payback at your actual entered rate | 16.7 years |
- This uses planning estimates you entered, not a contractor quote or guaranteed savings.
- It solves for the electricity rate that meets your target payback; it does not predict future rates.
What this also tells you: Your actual entered rate gives a payback of 16.7 years; the rate above is only the threshold for your stated target, not a forecast.
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
Backup power economics are unusually sensitive to your specific electricity rate, and this tool isolates that sensitivity directly rather than burying it inside one fixed-rate estimate.
How this is calculated
Given your system's net cost, expected annual kWh impact from rate-based savings, and a target payback period, this solves for the electricity rate that makes those three numbers work out exactly, and shows your actual payback at the real rate you enter.
A worked example
With the defaults ($12,000 net cost, 4,000 kWh/year, 10-year target), the required rate is $0.300/kWh, a notably high threshold reflecting how much rate-based savings alone would need to be worth to justify a system this expensive on that basis. Most households would need to lean on outage protection value or an incentive as well.
Common mistakes
A common mistake is assuming rate-based savings alone should justify a backup system's full cost. For many households, the honest economic case combines rate savings, outage protection, and incentives together.
Limitations
This does not model a rate that changes over your ownership horizon, and it does not verify your annual kWh savings estimate, which should come from your actual rate plan and usage pattern.
Common questions
Does this apply to a battery, a generator, or both?
It applies to whichever system's rate-based savings (arbitrage or demand-charge reduction) you enter. A generator with no rate-based savings would not fit this tool well; use its dedicated payback tool instead.
What if my rate is well below the required threshold?
That means the system does not clear your target payback on rate savings alone at current prices. Outage protection value or a confirmed incentive may still justify the purchase; check those tools too.
Does this account for rates that change over time?
No, it holds your rate constant to solve for the threshold. Treat the result as a snapshot against today's numbers, not a forecast.
Is this the same math as the breakeven-rate tools in other clusters?
Yes, the same underlying breakeven logic is used across the site; this version is scoped to a backup system's rate-based savings specifically.
What if my system captures both rate arbitrage and demand-charge savings?
Enter the combined kWh-equivalent savings figure across both value streams for this calculation, since it solves for one blended rate threshold.