Every product we recommend is chosen by research and calculation. We research and compare; we do not run our own product trials, and we never imply that we have. This page explains where our information comes from, how we narrow a category down to a short list, how we rank it, and what the Yard & Grid Score on each product card does and does not mean.
Where our information comes from
- Manufacturer documentation: spec sheets, user manuals, and warranty terms for figures such as rated output, battery capacity, charge input, coverage area, and operating temperature range. If a manufacturer does not publish a figure, we say that it is unpublished.
- Public agencies and standards bodies: guidance from the CPSC, FEMA, NOAA, USDA, DOE, and NFPA, plus university extension publications for garden topics. We use these for safety rules, climate and zone data, and planning figures.
- Published independent measurements: when a reviewer or publication has measured something such as usable battery capacity or noise, we cite that source by name and treat the result as theirs, not ours.
- Public buyer feedback: reviews and owner discussions on retail listings and forums. We look for problems that repeat across many owners, such as a fan that runs loud under moderate load or a seal that fails after one winter, and we give little weight to one-off complaints.
How we narrow a category
Before we look at individual products, we define the job. For a backup power guide that might be “keep a full-size refrigerator, a few lights, and a phone charger running overnight.” For a dehumidifier guide it might be “a finished basement that stays damp through summer.” The job sets the minimum specifications, and products that cannot meet them are dropped.
From there we look at products that are currently sold in the United States, have enough public buyer feedback to judge, and have manufacturer documentation we can verify. We leave out products that are discontinued, hard to find, or sold with specifications we cannot confirm. When a category only has a few strong options, we publish a shorter list instead of padding it.
The math we show
Most of our guides include at least one calculation, and we always show the formula. Each assumption gets a name and a reason. A typical example:
A 2,000 Wh power station running a refrigerator that averages 140 W: 2,000 Wh x 0.85 inverter efficiency / 140 W = about 12 hours.
The 0.85 is a common planning figure for losses when a battery’s DC power is converted to household AC power. We round down when the number is one you would rely on during an outage, and we write “about” because real appliances cycle on and off. You can swap in your own appliance’s wattage and get your own answer.
How we rank products
Our rankings are an editorial judgment. We weigh how well each product fits the job we defined, based on its specifications, the documented limits in its manual, the recurring patterns in buyer feedback, and the needs of the households the guide is written for. A product that suits an apartment balcony may rank lower in a guide written for a house with a well pump, and the reverse.
Every product in a buying guide gets a “Best for” and an “Avoid if” note. The “Avoid if” line names a real situation where the product is the wrong choice, so you can rule it out quickly.
The Yard & Grid Score
The Yard & Grid Score is the number from 5.0 to 9.5 shown on our product cards. It is a conversion of the average star rating that verified buyers have given the product on Amazon. We calculate it with one formula, applied the same way to every product:
Yard & Grid Score = 6.5 + (average star rating minus 3.0) x 1.5, kept within a floor of 5.0 and a ceiling of 9.5.
| Average buyer rating | Calculation | Yard & Grid Score |
|---|---|---|
| 5.0 stars | 6.5 + (5.0 minus 3.0) x 1.5 | 9.5 |
| 4.6 stars | 6.5 + (4.6 minus 3.0) x 1.5 | 8.9 |
| 4.2 stars | 6.5 + (4.2 minus 3.0) x 1.5 | 8.3 |
| 3.8 stars | 6.5 + (3.8 minus 3.0) x 1.5 | 7.7 |
| 3.0 stars | 6.5 + (3.0 minus 3.0) x 1.5 | 6.5 |
| 2.0 stars or lower | 6.5 + (2.0 minus 3.0) x 1.5 | 5.0 (floor) |
What the score means
The score reflects how satisfied buyers say they are. It is not a measurement made by Yard & Grid, and it is not a rating of power output, build quality, or safety. We do not add hidden weights, adjust it for any commercial reason, or blend in our own opinion. Because the ratings behind it change as new buyers leave reviews, the score on a card can move over time.
Why the ranking and the score can disagree
The order of products in a guide is our editorial ranking, so it will not always match the order of their scores. A product with a higher score may sit lower on a list because it cannot carry the load the guide is about, or because its manual limits it in a way that matters for that household. A product with a modest score may rank high because it is the only one that fits the job. Read the score as one signal about owner satisfaction, and read the article to decide what fits your home.
What we do not do
- We do not write prices into our articles. Prices change often, and the retailer’s page shows the current one.
- We do not accept payment, free products, or any other arrangement in exchange for coverage, rankings, or scores.
- We do not let affiliate commissions decide which products we include or where they rank. See our Affiliate Disclosure.
- We do not provide wiring instructions. When a project involves a home’s electrical panel, we explain the concept and recommend a licensed electrician. See our Safety Notice.
Updates
Each guide shows when it was published and when it was last updated, and longer guides end with a short changelog. When a product is discontinued, a manufacturer changes a specification, or agency guidance changes, we update the article and note it. If you find an error, please email [email protected]. Our broader standards are in our Editorial Policy.