Test a solar cash-payback scenario from entered all-in cost, verified incentives, tariff-aware year-one savings, recurring costs, and horizon.
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Test one entered solar cash-purchase scenario by accumulating year-specific net operating benefits against verified net upfront cost without assuming incentives, rates, financing, taxes or investment suitability.
Use actual all-in prices and tariff-aware year-one savings rather than generic averages.
Enter written cash cost, verified upfront incentives, savings, recurring costs, change assumption and ownership horizon.
Can see the crossing year or no-payback state and reproduce every cash-flow input.
Avoid relying on an expired or inapplicable benefit.
Start at $0, verify owner/property/equipment/timing against the official source, then add only the applicable upfront amount.
Does not enter the former U.S. residential federal credit for post-2025 property.
Recognize that cash payback is not the contract comparison.
Use the cash case only as a reference, then separately review fees, interest/escalators, ownership, incentives, warranties, termination and transfer.
Does not treat the undiscounted scenario return as investment ROI or contract approval.
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
This tool is part of these guided projects. Each project provides step-by-step instructions with checklists and all the tools you need in one place.
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Start with a dated written all-in cash proposal and subtract only upfront incentives verified for the owner, property, equipment and placed-in-service date. Current IRS guidance says the U.S. Residential Clean Energy Credit is not available for property placed in service after December 31, 2025; other programs and jurisdictions must be checked separately.
Entered net upfront cost = entered all-in cash cost − verified upfront incentivesEnter year-one bill savings from a model that distinguishes self-consumption, exports, fixed/minimum charges, time-varying rates and utility compensation. Subtract only sourced recurring costs. Future savings change is an explicit scenario assumption; the FTC notes future utility rates are hard to predict.
Year N net operating benefit = entered year-one savings × (1 + entered change)^(N−1) − entered annual recurring costsThe tool accumulates each year's net operating benefit and reports the fractional year in which it first reaches the entered net upfront cost, or states that no crossing occurs within the horizon. The scenario return is undiscounted and omits financing, opportunity cost and taxes beyond the entered incentive.
Scenario payback = first point where cumulative net operating benefit ≥ entered net upfront costUpdated: August 2026
$18,000 entered cash cost, $0 verified incentives, $1,800 year-one bill savings, $100 annual recurring cost and 0% change produce $1,700 year-one net operating benefit and a 10.59-year scenario payback. Over 25 years, net benefit after upfront cost is $24,500 before discounting or omitted risks.
Run the same written proposal once with $0 and once with a currently verified upfront local incentive. Preserve the program link, eligibility decision and date; do not enter an expired, transferable, refundable or owner-only benefit unless it actually applies.
$25,000 net upfront cost with $1,000 year-one savings, $100 annual recurring cost and 0% change accumulates $18,000 of net operating benefit over 20 years. The correct result is “Not within 20 years,” not an extrapolated promise.
Use the official program source and confirm owner, property, equipment, timing, tax treatment and whether the benefit is upfront. Keep uncertain or future amounts out of the base case.
Model each year consistently, subtract recurring costs, state the change assumption, keep production/tariff/financing uncertainty visible, and compare with a 0% and adverse case.
Test whether one entered cash-purchase scenario recovers its net upfront cost within a selected whole-year horizon. The calculation preserves verified incentives, year-one bill savings, recurring costs, and an explicit annual savings-change assumption. It does not assume a current tax credit, forecast utility rates, or model a loan, lease, PPA, tax return, investment alternative, or site production.