Updated October 2026
energycostmap publishes the break-even period for a residential solar system in each US state, calculated from public data and each utility's own tariff, with no federal tax credit applied. It exists because the figure most sites publish is still the one that was true before Section 25D expired on 31 December 2025.
Chameera Sampath
Compiler and maintainer, energycostmap
August 2026
50 states, each verified against the serving utility's tariff
None. No investor, no installer, no sponsor.
Until the end of 2025 a 30% federal tax credit took several thousand dollars off the price of a residential solar system and shortened almost every payback period in the country by three to five years. Section 25D expired. A year later, most solar calculators, installer pages and comparison guides still subtract that credit, which makes the figures they publish several years shorter than anything a buyer can now achieve.
Correcting that is mechanical work rather than clever work: read each state's net metering rule and the serving utility's tariff, record what is actually paid for exported power and how often the meter is netted, and run the arithmetic again with the credit set to zero. Nobody appeared to be doing it state by state, so this site does.
A state page appears only after its export terms have been read from a primary source — a public utility commission order, a rule in the state code, or the utility's own filed tariff sheet. Secondary summaries are used to find the document, never as the figure. Each state page names what was checked and the month it was checked in, and the method page sets out every assumption and every deliberate omission.
Two states were held back for weeks because their published figures could not be reconciled with the tariff. Illinois was held until the Illinois Shines payout could be established in dollars rather than in certificate prices; Kentucky was held until the LG&E export rate set in PSC Case 2021-00397 was confirmed. Publishing a figure that cannot be traced to a document is the one thing the site will not do.
The figures have been wrong before. A reader pointed out that Hawaii's $5,000 state tax credit cap applies per 5 kW of capacity rather than per installation, which meant a 6 kW array earned $6,488 rather than $5,000 and the page understated it. The page was corrected, and the credit caps in the other four states with percentage-based credits were rechecked in case the same mistake had been made there.
That is the intended process. Any figure here may be wrong. A report identifying the state and the figure concerned, sent to corrections@energycostmap.com, is rechecked against the source, and any change is recorded in the change log.
The complete dataset is published as states.json under CC BY 4.0, free for any use including commercial and republication, with attribution. It is the same file the pages are built from rather than an export prepared separately, so the two cannot disagree. A citable version is archived with a DOI at 10.5281/zenodo.22305313, and the repository carries the field documentation.
Corrections, data questions and press enquiries: corrections@energycostmap.com, or LinkedIn.
Figures on this site are estimates for comparison between states. They are not financial advice, not a quotation, and not a system design. At least three written quotations are advisable before any purchase.