Does solar actually pay back?

Year-by-year cash flow with exports valued separately from self-consumption, an IRR that refuses to mislead you, and a sensitivity table for the assumptions that matter.

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Does solar pay back?

Year-by-year cash flow, with exported energy valued separately from what you use yourself.

Symbol only — no conversion.
Only what you have confirmed you qualify for. Nothing is assumed.

Energy and tariffs

Without a battery, homes typically self-consume 25–50%.
What your utility actually pays for exports. Often far below retail.

Ongoing costs and discounting

What your money could earn elsewhere.

Paying for it

Year by year

If the assumptions are wrong

Each row changes one thing and leaves everything else alone.

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Your data stays in this browser. Everything on this page is calculated on your own device. Your electricity use, roof dimensions, prices and equipment details are never uploaded, stored on a server, or included in analytics.
Planning estimate — not an engineering or installation plan. Results depend on the information and assumptions you enter. Output, savings and equipment behaviour vary with weather, shading, tariffs, temperature, ageing and installation. Verify equipment limits against current manufacturer documentation. Permits, structural capacity, electrical protection, conductor sizing, grounding, rapid shutdown, fire access, utility interconnection and code compliance must be reviewed by qualified professionals and the applicable authorities.
Educational estimate, not financial advice. This is not tax, legal, financial or investment advice, and it makes no guarantee of savings. Incentive eligibility and utility policies change and vary by location — confirm them with the relevant programme, your utility and a qualified adviser before relying on any figure here.
How this is calculated

netInitialCost = installedCost − upfrontIncentives

yearNProduction = year1 × (1 − degradation)^(N−1)
yearNRate = year1Rate × (1 + escalation)^(N−1)
yearNSavings = selfUsedKWh × retailRate + exportedKWh × exportRate − maintenance − replacements − loanPayments

Payback is the interpolated point where cumulative cash flow crosses zero — a fraction of a year, not a rounded one. If it never crosses, the tool says so rather than returning infinity.

IRR is refused when it would be misleading. An inverter replacement makes the cash flows change direction more than once, and such a series can satisfy several different rates of return. Quoting one would look authoritative and mean nothing, so the tool points you at NPV instead.

Self-consumed and exported energy are valued separately. Treating them as equal is the single biggest reason payback estimates come out too optimistic where net metering has been retired.

Fixed supply charges are excluded from savings, because solar does not avoid them. All figures are nominal — inflation is not removed.

Why the export rate matters so much

Under full net metering, a kilowatt-hour you export is worth the same as one you avoid buying, so self-consumption barely matters. That arrangement has been ending in many places. Where exports earn a fraction of retail, a system generating far more than the house uses during the day gives most of its output away cheaply — and payback stretches by years. If you take one thing from this page, make it checking what your utility actually pays for exports before you sign anything.

What this does not assume

No tax credit. No rebate. No net-metering arrangement. No feed-in tariff. Those exist, they are often substantial, and eligibility depends on where you live, what you earn, what you install and when — none of which a calculator can verify. If you have confirmed one applies to you, enter it in the incentives field and it will be counted exactly as you typed it.

Limitations

This is a nominal cash-flow model. It does not handle tax treatment of income or depreciation, time-of-use tariffs, demand charges, battery arbitrage, changes in your consumption, or the effect on your property's value. It also cannot tell you whether your utility's rates will actually rise at the rate you entered — that assumption compounds over 25 years and deserves more scrutiny than any other number on this page.