United States version
How it works
Value stored electricity after charging losses and the opportunity cost of the charging energy.
This is the United States planning view, with monetary inputs and outputs in USD. A currency label does not establish that a tax rate, construction price, coverage rule or legal limit has been verified locally. The inputs and limitations below describe the actual scope.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
15-
?capacity=Nameplate battery capacity, kWhNumber · Required · Default: 10
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?usablePercent=Usable capacityPercentage · Required · Default: 90
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?cycles=Equivalent full cycles per yearNumber · Required · Default: 250
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?roundTripEfficiency=AC round-trip efficiencyPercentage · Required · Default: 90
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?peakRate=Avoided high-price electricity per kWhMoney · Required · Default: 0.3
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?chargingRate=Charging energy opportunity cost per kWhMoney · Required · Default: 0.1
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?projectCost=Installed battery priceMoney · Required · Default: 10,000
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?incentive=Confirmed incentiveMoney · Required · Default: 0
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?maintenance=Annual maintenanceMoney · Required · Default: 0
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?years=Planning horizon, yearsNumber · Required · Default: 25
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?discountRate=Annual discount ratePercentage · Required · Default: 4
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?degradation=Annual output degradationPercentage · Required · Default: 0.5
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?energyEscalation=Annual energy-price escalationPercentage · Required · Default: 2
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?replacementYear=Replacement year (0 means none)Number · Required · Default: 0
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?replacementCost=Replacement costMoney · Required · Default: 0
Outputs
8-
capitalNet capital costCurrency · Currency: USD
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annualSavingFirst-year net savingCurrency · Currency: USD
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paybackSimple payback, yearsNumber · Primary output
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npvDiscounted net valueCurrency · Currency: USD
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deliveredFirst-year delivered electricity, kWhNumber
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chargedFirst-year charging electricity, kWhNumber
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breakevenCash-flow break-even yearNumber
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cumulativeUndiscounted lifetime net benefitCurrency · Currency: USD
Formula
arbitrage benefit = usable kWh × cycles × peak price − charged kWh × charging price.
Calculations retain numeric precision internally. Displayed values are rounded for readability. Quantities that must be purchased as whole units are rounded up only where the formula explicitly requires it.
Read the inputs before calculating
- Nameplate battery capacity, kWh: Enter the quantity described by the label.
- Usable capacity: Enter the quantity described by the label.
- Equivalent full cycles per year: Enter the quantity described by the label.
- AC round-trip efficiency: Enter the quantity described by the label.
- Avoided high-price electricity per kWh: Enter the quantity described by the label.
- Charging energy opportunity cost per kWh: Enter the quantity described by the label.
- Installed battery price: Enter the quantity described by the label.
- Confirmed incentive: Enter the quantity described by the label.
- Annual maintenance: Enter the quantity described by the label.
- Planning horizon, years: Enter the quantity described by the label.
- Annual discount rate: Enter the quantity described by the label.
- Annual output degradation: Enter the quantity described by the label.
- Annual energy-price escalation: Enter the quantity described by the label.
- Replacement year (0 means none): Enter the quantity described by the label.
- Replacement cost: Enter the quantity described by the label.
Reproducible worked example
The following is a fictional arithmetic example, not a local quote, a verified claimant or a market forecast. Its values are included so the formula can be checked. The form does not automatically confirm any verification checkbox.
| Input | Example value |
|---|---|
| Nameplate battery capacity, kWh | 10 |
| Usable capacity | 90 |
| Equivalent full cycles per year | 250 |
| AC round-trip efficiency | 90 |
| Avoided high-price electricity per kWh | 0.3 |
| Charging energy opportunity cost per kWh | 0.1 |
| Installed battery price | 10,000 |
| Confirmed incentive | 0 |
| Annual maintenance | 0 |
| Planning horizon, years | 25 |
| Annual discount rate | 4 |
| Annual output degradation | 0.5 |
| Annual energy-price escalation | 2 |
| Replacement year (0 means none) | 0 |
| Replacement cost | 0 |
| Output | Calculated result |
|---|---|
| Net capital cost | USD 10,000 |
| First-year net saving | USD 425 |
| Simple payback, years | 23.5294 |
| Discounted net value | USD -2,260.8514 |
| First-year delivered electricity, kWh | 2,250 |
| First-year charging electricity, kWh | 2,500 |
| Cash-flow break-even year | 20.3188 |
| Undiscounted lifetime net benefit | USD 2,760.7197 |
Interpreting a changed assumption
Start with one complete scenario and change only one input when diagnosing a difference. Recheck units, the period of every rate, whether an amount is recurring or one-off, and whether a cost is already included elsewhere. A larger calculated benefit is not evidence that an assumption is more likely to occur.
Limitations
- Do not count the same solar export payment and time-of-use saving twice. Backup resilience is not monetized automatically. Replacement and warranty cycle limits require a product-specific assessment.
Frequently asked questions
What does this Home Battery Economics result represent?
Value stored electricity after charging losses and the opportunity cost of the charging energy. It applies the displayed formula to your inputs; it does not infer omitted facts.
Are the starting amounts verified United States prices or legal rules?
No. Numeric defaults are illustrative unless an input or dated reference explicitly identifies a researched component. Currency is USD; local quotes, eligibility and unsupported rules must be entered and verified separately.
What must I check before relying on the result?
Check the input units, supplier or authority evidence, the stated model exclusions and the period used for costs. This arithmetic does not supply missing site-specific design or local legal rules.
Can I compare or share different assumptions?
Change one assumption at a time and use the browser-local project or share controls. A shared URL contains the encoded input values; do not include information you do not wish to disclose.
Sources and reference scope
- DOE energy-use arithmetic — retrieved 2026-09-24. Energy consumption versus power; not a local tariff or an approval of this implementation.
- PVWatts: site-specific solar estimation — retrieved 2026-09-24. External site-yield model. AskCalculators uses your entered yield; it does not call or reproduce PVWatts.
- DOE insulation overview — retrieved 2026-09-24. Insulation and thermal resistance concepts; not structural or code approval.
These references support only their stated scope. They are not evidence that every local rule or price needed by the master expansion has been loaded.