The most important page on this site. For each dataset we use, this page records: where it comes from, when we last keyed it in, and whether the refresh is automatic or manual.
| Dataset | Method | Snapshot | Next review |
|---|---|---|---|
| State electricity rates | Manual | May 2025 | Aug 2026 |
| Peak sun hours by state | Manual | May 2025 | May 2027 |
| Federal Residential Clean Energy Credit | Manual | May 2025 | Jan 2027 |
| Installed cost per watt (residential) | Manual | May 2025 | Aug 2026 |
| State and utility incentives | Manual | May 2025 | Aug 2026 |
All five datasets currently use the manual snapshot method: the operator reads the cited source and types the values into the configuration files in the codebase. No data is pulled automatically. This is intentional disclosure — earlier versions of the site implied automated freshness it did not have.
Three of the five datasets can be put on a live feed without disproportionate effort. Each is documented here so readers can hold the operator accountable to the timeline.
| Dataset | Live-feed mechanism | Effort | Status |
|---|---|---|---|
| State electricity rates | EIA Open Data API (api.eia.gov), free API key | ~1 day | Planned, not yet built. |
| Peak sun hours | NREL Solar Resource Data API (developer.nrel.gov), free API key | ~1 day | Planned, not yet built. |
| State incentives | DSIRE monthly CSV archive, parsed by the existing scripts/dsire_import.php |
~2 hours / month | Importer exists, schedule does not. |
| Cost-per-watt | No public API; depends on quarterly reports being released and read | Manual | Manual review every ~6 months. |
| Federal credit | Statutory law; changes only on Congressional amendment | Manual | Reviewed on every IRS rule change. |
If a value below is materially out of date, please report it via the contact form. Specific corrections (with a link to the current value in the cited source) are easier to act on than general comments.
Four inputs. Sixty seconds. Every number traceable to a public source.