P PaybackZIP

Methodology

Last updated: May 26, 2026 · Written by Heather George

Everything on PaybackZIP — the rebate calculator, the state guides, the product guides, the payback numbers — is built on data I collect and refresh manually every week. This page explains where the data comes from, how I verify it, and what to be cautious about.

The five sources that do the work

DSIRE (Database of State Incentives for Renewables and Efficiency)

Source URL: dsireusa.org

Maintained by the NC Clean Energy Technology Center at NC State University. Over 2,500 policies and incentives across 124 energy technologies. DSIRE is the ground truth for state and local incentives — I cross-check every state entry against it.

Caveat: DSIRE's update cadence lags a bit — sometimes 2–4 weeks behind program launches or closures. For time-sensitive changes I fall back to state energy office pages.

ENERGY STAR HEAR program tracker

Source URL: energystar.gov HEAR page

Official status list for the federal HEAR (Home Electrification and Appliance Rebates) rollout by state. This is what I use to determine whether HEAR is currently accepting applications in your state, or whether it's still launching or fully reserved.

Caveat: The tracker sometimes shows "approved" before contractor enrollment is complete. A state can be "open" on the tracker but have zero registered contractors in your county. State energy offices are more reliable for on-the-ground status.

State energy office pages

Each state has its own energy office. GEFA (Georgia), CEC (California), CO Energy Office, NYSERDA (New York), etc. These pages have the freshest status updates — often days ahead of DSIRE and sometimes ahead of the ENERGY STAR tracker.

For the 11 states with deep coverage on PaybackZIP, I check the state energy office page for each every week during the refresh cycle. Links to every state's official page are on the corresponding state guide.

Utility residential efficiency pages

Each investor-owned utility publishes its residential rebate program on its own site. PG&E's is different from Xcel Colorado's, which is different from Duke Energy Carolinas'. I track programs for the top 13 utilities across the 11 deep-coverage states.

Caveat: Utility rebate amounts occasionally change mid-year without press release. When I catch a change, it gets logged on the updates page.

EIA (Energy Information Administration)

Source URL: eia.gov monthly electricity report

State-averaged residential electricity rates. Used in the calculator's payback math to scale annual savings by how expensive electricity is where you live. Refreshed quarterly (EIA publishes monthly, but state averages don't shift enough day-to-day to justify a weekly re-pull).

The weekly refresh cycle

Every Monday morning, I go through the same routine:

  1. Open the ENERGY STAR HEAR tracker and check any state that had a status change flagged in the previous week's DSIRE alerts.
  2. Visit each of the 11 deep-coverage state energy office pages. Look for banner announcements, funding updates, or contractor-list revisions.
  3. Check the 13 utility residential rebate pages for any dollar-amount or eligibility changes.
  4. Cross-reference reader emails from the past week — every correction or missed program gets validated against a primary source before it lands.
  5. Update src/data/rebates.json, src/data/states.json, and the state editorial files as needed.
  6. Log every change on the updates page, with the source URL, the specific change, and the date it took effect.
  7. Rebuild and redeploy the site.

When something breaks mid-week — a state suddenly closes its HEAR program, a utility overhauls its rebate structure — I run an off-cycle update rather than waiting for Monday. Those show up on the updates page dated when they happened.

How the AMI estimate works

HEAR eligibility depends on your Area Median Income (AMI) percentage. The calculator estimates AMI by:

  1. Looking up your state's four-person median household income (source: US Census ACS 5-year + HUD state-level income limits, 2024–2025 vintage).
  2. Adjusting for your household size using HUD's standard factors: 70% of the four-person median for one person, 80% for two, 90% for three, 100% for four, and up from there.
  3. Dividing your reported annual household income by that adjusted median.

This lands you in one of three tiers: ≤80% AMI (100% of project cost covered under HEAR, up to program caps), 80–150% AMI (50% of cost covered), or above 150% AMI (not HEAR-eligible, but state and utility programs may still apply).

Important caveat: HUD's official eligibility uses metro-area median income, not state median. For metros with high income variance (NYC, SF Bay Area, DC), the state estimate can be 20–30% off. Before applying for HEAR, look up your county or metro's official AMI on HUD's income limits page.

How the payback estimate works

Payback = net cost (project cost minus applicable rebates) divided by expected annual savings.

This is a simplification. Real payback depends on your current heating fuel, your home's envelope, your electric rate plan (time-of-use vs standard tiered), and behavioral factors. The calculator's payback number is a reasonable midpoint, not a guarantee.

Corrections process

If you notice a program that we've missed, a status that's out of date, or a rebate amount that's wrong, email hello@paybackzip.com. I read every message. Corrections that can be verified against a primary source (state energy office page, utility rebate page, DSIRE entry) land in the next weekly refresh.

Material corrections get their own entry on the updates page, with attribution to the reader if you'd like the credit. Anonymous submissions are also fine — the updates page will note the correction without a name.

What's on the roadmap

Data-related priorities for the rest of 2026: