Methodology

This site is a record of plug-in solar law in all 50 states and DC. It is only useful if it is right, so the rules below are strict and we would rather show a gap than a guess.

What counts as a source

A state’s status must come from an official source: the legislature’s own bill page or enacted text, a public utility commission order or rule, a state code site, or a governor’s office signing release. News stories, manufacturer pages, advocacy groups and other guide sites can tell us a bill exists. They are never the citation.

If a fact can’t be confirmed on an official source, the record leaves it empty and the page shows “—”. We don’t fill a watt cap or a date because another state’s law used that number.

The five statuses

• Legal: an enacted law specifically allows plug-in solar devices.
• Bill pending: no law yet, but a bill that would allow it is alive in the current session, confirmed on the legislature’s site.
• Unclear: official sources conflict or leave the answer genuinely open. The state page explains why.
• Not addressed: no statute addresses plug-in solar either way. This is the default. It does not mean illegal.
• Prohibited: an official source explicitly forbids these devices. We do not infer this from general interconnection rules.

When a record is in doubt it moves toward “Not addressed” or “Unclear”, never toward “Legal”.

Review dates

Every state page shows the date its record was last checked against its sources. Records are due for review every 60 days, and the page says so when one is late. A bill moving in a legislature triggers a review sooner.

The savings numbers

• Electricity rates: the U.S. Energy Information Administration’s residential average for each state over the most recent 12 months.
• Solar output: PVGIS 5.3, European Commission Joint Research Centre, ERA5 weather data, run on 2026-09-21 for a panel hanging vertically on a railing, facing each direction, at one city per state that we name on each page. A tilted rooftop panel would make more. We model the railing because that’s where these kits go. Vertical panels do relatively better in northern states and worse near the Gulf, where the summer sun is high overhead.
• Our own assumptions (shade factors, the share of output you use, the default kit price) are labelled as ours wherever they appear, and you can change every one of them in the calculator.

How we pick kits

The kits on this site are research picks. We list kits sold in the US and compare them on what their makers and sellers publish: output, certification, warranty and price. Each figure links to the page we read it from, with the date we read it. Where a maker doesn’t publish a figure, the card says so.

We don’t score kits, and an affiliate relationship doesn’t change which kits we list or their order. Each card says whether we earn anything from it.

What we have not done

We have not tested any plug-in solar kit ourselves. When we write about products, we’ll say what we know and where it came from, and we won’t imply hands-on testing that didn’t happen.

Corrections

If a record is wrong or out of date, email hello@mlighthouse.com with the bill number or the official link. We check it against the source and update the record and its review date.