How we verify

This site exists to be right, not to be first. These are the rules we follow.

State laws

Primary sources only. Every legal fact (status, bill number, dates, size limit, battery rules, utility notice, landlord and HOA rules, certification, net metering) must come from the legislature's bill page, the enacted or chaptered text, a governor's signing record, or a state utility commission page.
Trackers and news find leads; they are not evidence. When a tracker and the law disagree, the law wins, and we log the conflict.
Every rule shows its source. Each row in a state's rules table links to the section of the law it comes from.
No guesses. If we cannot confirm a fact, we mark it "unknown" and explain why. We do not estimate dates, wattages or certifications.
Derived dates are labelled. Some laws don't print a calendar date. They take effect "six months after enactment" or on a constitutional default date. We work out the date and mark it as derived.

Each state page carries a verification level. Today 26 records are fully traced to primary sources. 25 have a note explaining what is still unconfirmed. We could not yet confirm the status in Arizona, Delaware, Hawaii, Illinois, Ohio, Rhode Island, because their legislature websites did not load for our research tools. We list them as "status not yet confirmed" rather than repeat a tracker.

Kits and certification

Certified: we have seen the certifier's public directory entry or a certificate document.
Claimed: the maker says so, but we found no certificate.
Not certified: the maker or seller says it is not certified.
Unknown: no claim and no evidence either way.

We also record what a certificate covers: a single component, such as the inverter, or the complete system you plug in. State laws come in two kinds, and we judge kits differently for each.

UL 3700 or complete-system states (Vermont, Maine, New Jersey, California): a kit is compatible only with a certificate for the complete system. A certificate for one part is shown as "Component certificate only: check with seller". Maine also allows a system configured per the National Electrical Code. We don't judge that route; ask a licensed electrician.
Lab-listed states (Utah, Maryland, Colorado, Connecticut, Virginia): the law asks for certification by UL or an equivalent lab without naming a standard. If we have seen a lab certificate for the kit's inverter, we show "Likely compatible: confirm with seller". If the maker only claims a listing, we show "Listing claimed, no certificate seen". Connecticut also names UL 1741. Connecticut and Maryland allow one device or system per meter, so kits with several inverters carry a "check device count" note.

In every state the kit's stated output must be within the legal limit. If the seller doesn't state the output but the panels alone are under the limit, the kit cannot exceed it. Specs and prices come from the maker's or seller's own pages, with the date we checked. An output we calculated from the parts is labelled "estimated".

Savings estimates

Electricity prices are U.S. EIA residential averages for September 2025 – August 2026 (12 months): total revenue divided by total sales, from Form EIA-861M. Solar output comes from NREL (National Laboratory of the Rockies) PVWatts v8, typical meteorological year weather, run for each state capital in two cases: 20° tilt facing south, and vertical (90°) facing south. Where a figure is missing, we show no estimate.

Savings depend on how much of the output you use at home, because exports usually earn nothing. We show a best case (100%) and a typical case (69%). The typical case comes from HTW Berlin's Stecker-Solar-Simulator: 800 W, no battery, a home using 3,000 kWh a year. That is well below every US state's average household use. The model uses German weather and household patterns, so treat it as a guide.

Update schedule

We re-check every record at least weekly. We check sooner when a bill has a vote scheduled or a law is about to take effect. Each page shows the date it was last checked. Every change is logged on the updates page and in its RSS feed.

Records last checked: November 10, 2026 (oldest state record) · 10 kits tracked.

Corrections

If you find an error, we want to know. Corrections are logged on the updates page with the source we used.