Data / Index, September 2026
Solar Economics Index / September 2026
Solar Economics Index, September 2026
The 11 states we published in September 2026, ranked by how long rooftop solar took to repay itself on one identical house: from 5.7 yr in New York to 13.5 yr in Arizona. Cut 6 September 2026 and frozen on that date.
This page is a permanent record and will not be revised. The current edition is October 2026. Download: 2026-09.csv.
The ranking, September 2026
11 states, ranked by the year a cash purchase repays itself. One reference house in every state: a $200 monthly electricity bill, statewide averages, 2026 federal policy, a system sized to cover that household's own use. Cut 2026-09-06 and frozen.
| # | State | Payback | Rate | Installed | Yield | System | Net cost | Year 1 | 25-year net |
|---|---|---|---|---|---|---|---|---|---|
| 1 | New York | 5.7 yr | 29.49¢ | $2.76/W | 1291 | 5.93 kW | $12,266 | $2,026 | $52,320 |
| 2 | New Jersey | 6.1 yr | 24.95¢ | $2.58/W | 1305 | 6.93 kW | $17,876 | $2,802 | $58,806 |
| 3 | Massachusetts | 7.1 yr | 29.61¢ | $2.91/W | 1302 | 5.85 kW | $16,029 | $2,106 | $50,567 |
| 4 | Illinois | 8.2 yr | 19.89¢ | $2.98/W | 1308 | 8.67 kW | $25,841 | $2,522 | $31,952 |
| 5 | Maryland | 8.5 yr | 21.84¢ | $2.62/W | 1392 | 7.42 kW | $19,442 | $2,106 | $47,154 |
| 6 | California | 8.6 yr | 34.74¢ | $2.48/W | 1677 | 3.87 kW | $9,603 | $1,023 | $22,359 |
| 7 | Pennsylvania | 8.6 yr | 21.73¢ | $2.58/W | 1359 | 7.64 kW | $19,710 | $2,106 | $46,886 |
| 8 | Florida | 8.9 yr | 15.1¢ | $2.12/W | 1544 | 9.68 kW | $20,514 | $2,106 | $46,082 |
| 9 | Connecticut | 10.3 yr | 24.32¢ | $2.72/W | 1252 | 7.41 kW | $20,153 | $1,733 | $37,657 |
| 10 | Texas | 11.1 yr | 15.94¢ | $2.22/W | 1506 | 9.4 kW | $20,863 | $1,700 | $32,745 |
| 11 | Arizona | 13.5 yr | 15.18¢ | $2.21/W | 1755 | 8.47 kW | $17,715 | $1,253 | $21,607 |
Payback in years on a cash purchase, after maintenance and an inverter replacement. Rate: cents per kilowatt-hour. Installed: dollars per watt before incentives, on the quoted basis. Yield: kilowatt-hours per kilowatt per year. Every input is in the data index, with the source it was read from.
One sentence per state
Written at the cut and stored with the edition, so a sentence quoted from this page says the same thing for ever. Take any of them.
- New York ranks 1st of 11 for solar payback in September 2026, at 5.7 years.
- New Jersey ranks 2nd of 11 for solar payback in September 2026, at 6.1 years.
- Massachusetts ranks 3rd of 11 for solar payback in September 2026, at 7.1 years.
- Illinois ranks 4th of 11 for solar payback in September 2026, at 8.2 years.
- Maryland ranks 5th of 11 for solar payback in September 2026, at 8.5 years.
- California ranks 6th of 11 for solar payback in September 2026, at 8.6 years.
- Pennsylvania ranks 7th of 11 for solar payback in September 2026, at 8.6 years.
- Florida ranks 8th of 11 for solar payback in September 2026, at 8.9 years.
- Connecticut ranks 9th of 11 for solar payback in September 2026, at 10.3 years.
- Texas ranks 10th of 11 for solar payback in September 2026, at 11.1 years.
- Arizona ranks 11th of 11 for solar payback in September 2026, at 13.5 years.
What this edition was computed from
| Electricity prices | EIA 2026-06, read 2026-09-05 |
| Solar yield | PVWatts v8 (verified), read 2026-09-05 |
| Installed cost | EnergySage 2026, read 2026-09-05 |
| Export rules | read 2026-09-05 |
| State incentives | read 2026-09-05 |
| Federal policy | 2026, read 2026-09-05 |
| Modelling assumptions | set 2026-09-04 |
Each of those is a file you can download whole, with every record and its source, from the data index. The formulas that consume them are on the methodology page.
What had moved
The first edition of the index, so there was nothing to compare it against. Every edition after this one carries the movements against the one before it, with the published input that caused each.
Either side of this edition
- October 2026
The edition after. New York led at 5.7 years.
- The data behind it
Every record this edition was computed from, with its source and the date it was read.
The rest of the data
- Electricity prices
What a residential kilowatt-hour costs, by state. The single biggest driver of whether solar pays.
- Solar yield
How much electricity a kilowatt of panels makes in a year, by place. The only pure physics on the site.
- Installed cost
What a system costs installed, on both published bases: competitive quotes, and what buyers actually paid.
- Export rules
What the utility pays for a kilowatt-hour you send out. Decides payback more than sunshine does.
- State incentives
What a buyer can actually claim from a state, read from the statute or programme that grants it.
- Federal policy
The federal credit as data, versioned by year, with the dated events that changed it.
- Modelling assumptions
Everything the model assumes rather than sources: panel wattage, degradation, loan terms, escalation.
Published 6 September 2026. Last verified 6 September 2026. A figure here that looks wrong is the mail we most want: tell us, and we publish corrections. The formulas that consume these records are on the methodology page.