Editorial Standards

Our rules

• No invented numbers. Every state electricity rate is reproduced verbatim from EIA. Where a measured state figure is unavailable, the value is a labeled modeling benchmark — never presented as a measurement.
• Measured vs modeled, on the page. Each state page states whether its installed $/W came from EnergySage or from the national benchmark, and whether its export regime was verified.
• Current law, dated. The federal credit treatment is pinned to a named IRS document and a date. Deprecated rules are described as historical, never applied.
• One kernel. Static tables and interactive results come from the same equations and are cross-checked before deployment.
• Uncertainty is visible. Known omissions are listed on the methodology page and on every calculator page's "what this tool does not do" section.
• Corrections are public. Material changes are logged with the date, the affected pages and the reason.
• Independence. HelioCalc does not sell solar, does not collect leads, and does not accept payment for a placement in a calculation. If affiliate links are added in future, they will be labeled and will never change a computed number.

Who publishes this site

HelioCalc is published by the HelioCalc organization and maintained by Jian Yuan (also written Yuan Jian), who is accountable for the state dataset, the calculation model, these editorial standards and the public corrections log. We claim no professional credential, license, installer experience or engineering qualification: solar payback is a household finance topic, and we would rather be explicit about who is accountable than imply an expertise we cannot demonstrate. The author page describes the person behind the byline; this page describes the process behind the numbers. Use the contact page for corrections and questions; material corrections are logged publicly on the corrections page.

How the content is made

Every page is produced by one versioned generator from a single dataset, with AI-assisted drafting of explanatory prose and human checking of each number against its primary source. No figure is invented: residential rates are reproduced verbatim from EIA Table 5.6.A (August 2026); installed prices are EnergySage September 2026 state marketplace averages for twelve states and a clearly labeled 2.80 $/W national modeling benchmark elsewhere; peak sun hours are NREL-derived planning bands; the federal rule is pinned to IRS FS-2025-05. Where a statewide incentive or export rule could not be verified, the model uses $0 or a conservative export credit and says so on the page.

Automation is used because keeping 51 jurisdictions on one consistent, auditable rule set by hand is error-prone: a single generator lets the static answer tables, the browser calculator and the Python reference kernel be diffed field by field before every deployment. Every page states whether a value is measured or modeled, and the methodology page lists the known omissions. This disclosure exists so a reader can judge the estimate rather than trust a byline.

Why these pages exist

In 2026 a great deal of solar advice still quotes a 30% federal residential credit that ended with 2025. HelioCalc exists to give a homeowner a reproducible, source-labeled starting point under the law and tariffs that actually apply. The 51 state pages are not a bid for search traffic: each carries that state's own rate, cost basis, resource band, incentive stack, worked estimates at three bill levels, a comparison with the national model and its neighbours, and a calculator preloaded with those inputs. Nothing here is tax, legal or financial advice, and no computed number depends on a commercial relationship.

What we will not do

We will not publish a "typical" saving without the assumptions behind it, quote a tax credit that no longer exists, convert a planning benchmark into a state-specific claim, or hide an omission that would make a number look better. A calculator that flatters the answer is not a calculator.