Payback period
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Things to check
Cash versus loan
Incentives are taken off the cost at the start in both columns, so the two compare like for like. Payback, present value and return count only the cash you put in.
Year by year with the loan
After tax, for a business
The federal credit is taken off the cost at the start, as everywhere on this page. Tax then applies to the savings and the costs each year.
Paying cash
Using the loan
Year by year after tax
Cash before tax plus the tax effect is cash after tax. A plus in the tax effect column is tax saved, a minus is tax paid.
With the loan, cash before tax is what is left after the loan payments.
This is not tax advice. The defaults are common starting points. Confirm with your tax advisor.
The defaults assume a 25% combined tax rate, the 5-year depreciation schedule (MACRS) with no bonus depreciation, a cost to depreciate that is the installed cost less half of the credit, and enough tax owed to use every deduction in the year it arises.
The rules as summaries by law firms and trade groups describe them, checked on October 11, 2026 (the summaries, not the law itself):
- The federal credit for business solar ends for systems placed in service after December 31, 2027, unless construction began by July 4, 2026. What counts as having begun construction has been before a court, and the answer could change again.
- Bonus depreciation (part of the cost deducted in year 1) of 100% was restored for property acquired after January 19, 2025. Sources differ on whether that date means acquired or placed in service, and on whether the 5-year schedule still applies to solar whose construction began after 2024.
- The cost you can depreciate is reduced by half of the credit. This comes from summaries and was not checked against the law itself.
- Not included: state or utility incentives that count as income. The inverter replacement is deducted when it is paid, though it may have to be depreciated. A loan fee is spread evenly over the term of the loan here, and the tax treatment of fees can differ.
- Also not included: the size of the credit (the summaries say 30% only when wage and apprenticeship rules are met or the system is under 1 MW AC, otherwise 6%; set the credit under Costs and incentives), limits on foreign-made parts, the alternative minimum tax, limits on losses from passive activities, recapture of the credit, state rules that differ and a tax rate that changes.
Cumulative cash
Cumulative cashDiscounted to today
What moves the result
Lifetime breakdown
Tilt
Break-even and sensitivity
Each cell reruns the whole analysis with the installed cost per watt and the energy rate changed by the percentages shown. Nothing else changes.
Monthly detail
Year-by-year cash flow
Compare scenarios
Pick 2 to 4
Compare 2 to 4 setups side by side, from your saved projects or from the inputs on the page right now. Nothing here changes your inputs. A scenario is a copy taken when you add it. The list is kept only for this visit: it is not saved, not put in links, and gone when you reload.
Saved projects
To compare
Cumulative cash by scenario
Each line starts at the cash put in and climbs as savings arrive. A line ends where that scenario’s years end. Move over the chart, or focus it and use the left and right arrow keys, to read each year.
Cumulative cash by year, as a table
How this estimate works
Disclaimer: A planning estimate based on your inputs and the assumptions shown. Actual costs and eligibility may differ. Solar production estimates rely on NREL PVWatts historical weather models. Not financial, tax, or legal advice.