About SolarCostData: Data, Methods & Editorial Standards

What this site is for

Data vintages (current): State electricity rates: EIA Table 5.6.A, July 2026 data (released Sep 2026). The 17¢ US-average default in appliance and EV examples is the EIA 2025 full-year residential average (17.3¢, Table 5.3); the latest monthly figure (July 2026 US total) is 18.31¢. Utility tariffs: EIA-861 2024 final. Production: PVGIS v5.2 NSRDB. Installed cost: EnergySage marketplace, Aug 2026.

SolarCostData turns public energy data into direct answers about what energy actually costs you: to run an appliance, to charge a car, to heat a house, to put panels on a roof.

It exists because of a specific problem. The 2025 budget law ended most federal residential energy tax credits at the end of that year, and an enormous amount of otherwise-good online content became wrong overnight. Calculators still subtract 30% from solar systems. Dealer sheets still show $7,500 off an EV. Guides still describe a heat-pump credit that no longer exists. None of it is malicious — it is simply content written before the law changed and never revisited.

Longer arguments and state-by-state analyses live on the blog . Our whole editorial position is that being correct about 2026 is worth more than being optimistic about it.

What we cover

The site started with solar and has grown to cover household energy cost more broadly, because the questions people actually ask cut across all of it:

• Solar — cost, payback, and the honest post-credit math, state by state.
• Electricity and appliances — what any device costs to run, at your rate rather than a national average.
• EV charging — per-model running costs built from EPA efficiency data.
• Heat pumps and heating — operating cost against gas, propane, oil and resistance electric.
• Home batteries — payback under net billing, and who actually claims the credit.
• Energy tax credits — which federal credits survived into 2026, which did not, and what remains at state level.

How we model each thing

Different questions need different data, so the methods differ. All of them are stated on the page they apply to.

Electricity rates. Each state’s average residential rate from the EIA. Every calculator lets you override it with the figure from your own bill, which is always the better number — state averages hide enormous variation between utilities and rate plans.

Appliance running costs. Pure physics: watts ÷ 1,000 × hours × your rate per kWh. Wattages are given as typical ranges with a midpoint, and are explicitly planning values, not measurements of your unit. The nameplate on your own appliance beats any figure we can publish, and every tool lets you type it in.

EV charging costs. Efficiency (kWh per 100 miles) and range come from the EPA’s fueleconomy.gov dataset, averaged across the configurations the EPA lists for the current model year. We add roughly 10% for charging losses, because electricity drawn from the wall exceeds what reaches the battery — omitting this is the most common reason published EV running costs come out too low. “Energy for a full charge” is EPA range × efficiency, not the manufacturer’s battery capacity, because usable capacity is always less than the headline figure.

Solar cost and payback. System size modeled from about 1,200 kWh per kW per year (a US average — the Southwest beats it, the Pacific Northwest and New England fall short), market-average price per watt before incentives, the federal credit set to $0 for 2026 purchases, and a 25-year projection that raises utility rates and degrades panel output. Every one of those assumptions is printed under the result.

Tax credits. Read from IRS source material and reported with the section number attached, so you can check it yourself. Where a rule turns on a date or a test we cannot verify with confidence — begin-construction cutoffs, for example — we say so rather than guess.

The 2026 tax position, and why we keep repeating it

Because it is the single thing most likely to cost a reader real money, and the single thing most sites still get wrong:

• §25D , the residential clean energy credit that paid 30% on home solar and batteries, ended after December 31, 2025. The statute treats the expenditure as made when the installation is completed, not when you paid — so a system paid for in 2025 but finished in 2026 gets $0. There is no phase-down. Unused credit from a system completed in 2025 does carry forward to later years.
• §30D and §25E , the new and used clean vehicle credits, ended for vehicles acquired after September 30, 2025.
• §25C , the energy-efficient home improvement credit covering heat pumps, insulation and similar work, ended for property placed in service after December 31, 2025.
• §48E , the clean electricity investment credit, is a business credit and is still available to whoever owns the equipment. It reaches a homeowner only through a lease, PPA or third-party-owned arrangement — where the company claims it, not you. Storage runs far longer under it than solar does, and the much-quoted end-2027 solar cutoff binds only projects beginning construction after July 4, 2026.
• §30C , the credit for home EV charging equipment, ended June 30, 2026 (30% up to $1,000, eligible census tracts). Equipment placed in service by that date is still claimed on that year’s return; nothing installed later qualifies. With it gone, no federal energy credit remains that a homeowner can claim directly on a new 2026 purchase.
• State credits and utility programs are unaffected by the federal changes and continue on their own schedules. Six states still run a residential solar income-tax credit.

When we say a credit is dead, we mean for the person reading — a homeowner buying with their own money. That distinction is exactly where most of the confusion online comes from, so we make it explicitly every time.

Our principles

• Accuracy over optimism. We would rather publish a sobering correct payback than a flattering outdated one. If the honest answer is “at your electricity rate, this does not pay,” we print that.
• No fabricated numbers. Every figure traces to a public dataset or to a transparent assumption we disclose on the page. Where we do not have reliable data, we say so instead of filling the gap.
• Show the formula. Every calculator states its arithmetic. You should be able to check any result by hand, and disagree with our assumptions if you want to.
• No gates. No email walls, no “unlock your results,” no passing your details to installers. The tools work because you opened the page.
• Independence. We may earn from advertising or referrals. It does not change a number on this site.

Editorial standards and updates

• Sources. Electricity rates: EIA, average retail price by state and sales, revenue and price . Vehicle efficiency: EPA, fueleconomy.gov vehicle dataset . Incentives and net-metering rules: DSIRE (program index ), Database of State Incentives for Renewables & Efficiency, NC Clean Energy Technology Center, plus state and utility program records. Federal tax rules: IRS pages for each credit — §25D , §25C , §30D , §25E , §30C — and Public Law 119-21 (2025).
• Review cadence. Pages carry a visible “Updated” date and a dateModified signal. We revise when the underlying data or the law changes, not on a schedule for its own sake.
• Corrections. If a rate, incentive or rule looks wrong for your state or your utility, we want to know — accuracy is the entire proposition of the site.
• Not advice. Everything here is an estimate for orientation . Nothing on this site is tax, legal or financial advice for your specific situation, and no calculator output is a quote.

Methodology & data review

Until a named author page exists, this section is the accountability statement for everything published here.

• Who maintains this. The site is maintained by its operator (reachable at the contact page ); no editorial staff is claimed and no author identity is invented. Every page is reviewed against its primary sources before publication. The interactive tools added in September draw on the same primary-only rule: EIA Form 861 (service territories, revenue/sales), the EIA Short-Term Energy Outlook (regional degree-days), EPM archive editions (the rate tracker), the NEEP cold-climate heat-pump database, the Census ZCTA–county crosswalk, and utilities’ own tariff sheets — each cited with its vintage on the page that uses it.
• Data sources and update cycle. Electricity rates: EIA Table 5.6.A, refreshed when EIA publishes (about a 2-month lag, updated in the last week of each month). EV efficiency: EPA fueleconomy.gov dataset. Heat-pump performance: NEEP ccASHP database, deduplicated by outdoor unit. Incentives and export rules: state PUC/PSC documents and DSIRE, snapshot-dated on every page. Appliance benchmarks: ENERGY STAR criteria, EnergyGuide values and EIA RECS 2020 microdata.
• How figures are computed. One shared model (solarmodel) drives every payback figure on the site — the tools, all 51 state pages and every table — so no two pages can disagree. Each calculator prints its formula.
• Error reporting. Found a wrong rate, program status or tax fact? Email the address on the contact page with the page URL. Verified corrections are applied and the page’s “Data updated” date moves with them.

Accountability

Who publishes this. SolarCostData is an independent, one-operator publication. There is no installer, utility, lender or manufacturer money behind it: no lead forms, no paid placements, no affiliate quotes. Revenue, when it exists, is display advertising, which never influences a number on a page. Editorial output is signed collectively as the SolarCostData Data Desk; the publisher of record is the TyreMap Editorial Team .

Sourcing policy. Every figure traces to a primary public dataset named on the page — EIA (Electric Power Monthly, Natural Gas Monthly, SHOPP, STEO, EIA-861), EPA fueleconomy.gov, NEEP’s cold-climate heat pump database, RECS, DSIRE, state PUC filings and IRS guidance — with the data month printed next to it. Modeled outputs (paybacks, seasonal costs) are labelled as estimates and the formula is printed under every calculator. Where a primary figure does not exist (a state without a SHOPP series, a utility whose export terms are unverified) the page says so and shows a range instead of a single invented number.

Corrections policy. When a reader, a reviewer or our own gates find a factual error, we fix it at the source (data file or generator), redeploy, and record it in the corrections log with the date, what was wrong and what changed. Nothing is silently edited; the “Reviewed” date under each heading moves only when the page’s content actually changes.

How to reach us. Corrections, data-error reports and privacy requests go through the contact page . We answer with the fix or with why we disagree, and either way the log records it.

Frequently asked questions

Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.

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