Solar Break Even Time Calculator

Calculator

Enter costs, incentives, and energy assumptions.

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Currency

Used for display and exports.

Installed cost

Total contract price before rebates.

Upfront rebates

Instant discounts paid at installation.

Tax credit percent

Applied to cost after rebates.

Tax credit received in

Timing affects break-even.

Other incentive (Year 1)

Example: performance bonus, grant payment.

Production input mode

Use a site report when available.

System size (kW)

Peak sun hours per day

Performance ratio

Typical 0.75–0.88.

Annual generation (kWh)

From solar proposal or monitoring data.

Annual usage (kWh)

Usage change per year (%)

Example: EV adoption or efficiency upgrades.

Electricity rate (per kWh)

Rate escalation (%)

Annual tariff growth assumption.

Self‑consumption (%)

Portion of generation used on‑site.

Export credit (% of rate)

100% for full net metering.

Panel degradation (%/year)

Analysis horizon (years)

Discount rate (%)

Used for NPV only.

O&M mode

O&M percent (%)

Common range 0.5–2.0%.

O&M fixed (per year)

O&M inflation (%)

Inverter replacement year

Set 0 to disable.

Inverter replacement cost

Payment method

Down payment (%)

Loan APR (%)

Loan term (years)

Example data table

Sample scenario illustrating typical inputs and outputs.

Scenario	Installed cost	System size	Annual gen	Usage	Rate	Break-even
Urban home, net metering	$12,000	5.0 kW	~7,480 kWh	7,500 kWh	$0.16	~7–9 years
High usage, partial export credit	$18,500	7.5 kW	~11,200 kWh	12,000 kWh	$0.19	~6–8 years
Low export value, higher O&M	$10,800	4.0 kW	~5,980 kWh	6,500 kWh	$0.14	~9–12 years

Numbers are illustrative only; enter your local values for accuracy.

Formula used

This calculator models yearly cashflows and finds the first year where cumulative savings recover the upfront investment.

Estimated annual generation

Generation₁ = System kW × Sun hours/day × 365 × Performance ratio

If you already know annual generation, switch to manual mode.

Yearly savings value

Savings_y = Offset kWh × Rate_y + Export kWh × Rate_y × ExportCredit

Rates and usage can change each year using escalation inputs.

Cashflow and cumulative

Net_y = Savings_y − O&M_y − LoanPay_y + OneTime_y

Cumulative_y = Year0 + Σ Net_1..y

Break-even happens when cumulative crosses zero.

NPV (optional)

NPV = Year0 + Σ (Net_y / (1 + DiscountRate)^y)

NPV helps compare alternatives with different timelines.

How to use this calculator

Enter installed cost and any upfront rebates or discounts.
Choose a production input mode: estimate or manual generation.
Fill in annual usage, current electricity rate, and escalation assumptions.
Set self‑consumption and export credit to match your policy.
Open advanced settings for degradation, O&M, inverter, loan, and NPV.
Press Calculate Break-even Time to view results above the form.
Use the download buttons to export your results to CSV or PDF.

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