The short version: we do not have a test bench, we do not receive review units, and we never describe a published specification as though we measured it.
What we actually do
Every number on this site is derived, not observed. That is a real limitation and stating it plainly is more useful to you than pretending otherwise.
In practice, producing an article means four things:
- Pulling the primary figures. Appliance draw comes from the unit’s EnergyGuide label, the manufacturer’s published specification sheet, or the ENERGY STAR product finder. Equipment capacity, inverter rating and surge tolerance come from the manufacturer’s own manual, not from a retail listing.
- Pulling the reference rates. US electricity costs use the EIA Electric Power Monthly average residential rate. UK costs use the Ofgem price cap in force. Both are cited with the month they refer to, because both move.
- Doing the arithmetic in the open. Where an article calculates a runtime or a cost, the assumptions are printed alongside it: usable capacity against rated capacity, inverter efficiency, duty cycle. If you disagree with an assumption you can see it and redo the sum.
- Checking every figure before publication. A named person opens each source and confirms each number against it. Nothing goes live on the strength of a draft.
What we will not claim
- We will not present a specification sheet as a measurement.
- We will not write “we tested” about a product nobody here has run. Where a recommendation rests on published specifications and verified owner reviews, that is what the page says.
- We will not fill a table cell with a plausible-looking number. Where no reliable published figure exists, the cell reads varies by model, check the appliance label. An empty answer is worth more than a confident wrong one when somebody is about to spend $1,500.
Where the numbers come from
Only these classes of source are admissible: FTC EnergyGuide labels and ENERGY STAR; manufacturer specification sheets and manuals; the US Energy Information Administration; Ofgem; the US Consumer Product Safety Commission and the NFPA; the National Electrical Code (NFPA 70) and BS 7671; VDE-AR-N 4105 and the German Marktstammdatenregister; the Spanish REBT and ITC-BT-40; NOAA and the National Hurricane Center; and the text of the relevant statute where a rule is set by state law.
When this changes
If WattBackup ever acquires measurement equipment or begins receiving review units, this page will be rewritten to say so before any article relies on it, and the change will be dated. Until then, take everything here as careful desk research with its sources attached.