How We Evaluate Products

Sizing

Device energy equals average watts × hours. We divide that result by 0.85 for estimated conversion losses, then apply a separate 15% reserve to produce the suggested minimum manufacturer-rated battery capacity. These assumptions are applied once each.

Average power usage estimates energy over the requested duration. Maximum simultaneous running load sets the minimum continuous inverter output. The optional startup / surge requirement is a separate short-duration check for motors, compressors, pumps, and similar equipment. When supplied, a product must meet both output requirements and the rated-capacity requirement. We do not invent a surge requirement when that field is empty.

Presets are cited example planning values, not measurements of the user's equipment. Compressor and motor startup allowances are explicitly identified as estimates. Users should edit every value and check the appliance nameplate or manufacturer documentation. Actual runtime changes with temperature, load profile, battery age, and standby use.

Recommendation Match Score

Eligibility is a hard gate; ranking then looks for best fit rather than maximum capability. The score combines Capacity Fit, Output Fit, Use-case Fit, Portability and Feature Fit. We round the result to a whole number because it is a planning score, not laboratory precision. Price, retailer availability and affiliate commission are not inputs.

Capacity Fit uses rated capacity divided by the suggested rated minimum. Ratios from 1.0–1.5 receive near-full credit; 1.5–2.5 keeps useful headroom with a growing penalty; 2.5–4.0 is penalized more steeply; and capacity above 4× receives little additional credit. Home-backup features can improve other components, but they never remove this oversizing penalty.

Sources and product data

Specifications are stored once in a normalized product record. Official manufacturer product pages, manuals, and support documents are the primary sources. Other reputable sources may be used when a manufacturer source is unavailable or needs clarification. We link the source and show the last verification date on product pages.

What we compare

Structured comparisons consider rated and estimated usable capacity, continuous and surge output, battery chemistry and cycle life, weight and size, AC and solar charging, ports, expansion and UPS features, warranty, intended use case, and available price context. Estimated usable energy is a planning value of 85% of rated capacity, not a manufacturer claim.

Use-case scores

These weights are used for general product-to-product comparison. Calculator recommendations additionally use the requirement-aware Match Score described above. Scores explain tradeoffs; they do not replace checking appliance manuals or local electrical requirements.

Hands-on testing

Products are not presented as personally tested unless the page says so explicitly. The current database is based on specification research and transparent calculations rather than laboratory or long-term field testing.

Pricing and editorial independence

Prices and availability can change at any time and should be checked with the retailer. Affiliate commission rates are not inputs to our eligibility filters, comparison fields, or scoring weights. A commercial relationship does not guarantee inclusion or a favorable result.