Methodology
How we score
WattLab Review exists to make portable power stations comparable. Every product is stored as one structured record with the same fields, and every page, chart and comparison is generated from those records. Nothing is hand-tuned per product.
Where the specs come from
We start from the Amazon.com listing you'll buy from, then verify and complete every figure against the manufacturer's official spec sheet, user manual or product page, cross-checked with independent hands-on reviews. When sources disagree we use the manufacturer's published figure and note the discrepancy. When a number isn't published anywhere reliable, we show a dash. We never estimate a missing spec to fill a chart.
The seven score axes (0–10)
Each axis uses a fixed reference range for the whole category, not a curve relative to the models we happen to list, so scores never shift when we add new products.
| Axis | Rule |
|---|---|
| Capacity | 10 × log(Wh ÷ 50) ÷ log(3000 ÷ 50), clamped 0–10. 288 Wh ≈ 4.3; 1,070 Wh ≈ 7.5. |
| Power | 10 × log(continuous AC W ÷ 100) ÷ log(3600 ÷ 100). Surge is not counted. |
| Charging | 10 if the fastest official 0–100% time is ≤ 1 hr; falls logarithmically to 0 at 8 hr. |
| Battery tech | LiFePO4 starts at 6, NMC lithium-ion at 3; plus 1 point per 1,000 rated cycles (max +4). |
| Portability | 10 at ≤ 5 lb, falling logarithmically to 0 at 60 lb. |
| Solar input | 10 × log(max solar W ÷ 50) ÷ log(1200 ÷ 50). |
| Value | Wh per dollar at the reference price, log-scaled 0.3 → 0 to 3.0 → 10, with an editor adjustment of at most ±1 (e.g. −1 for older NMC chemistry). |
The WattLab Score
Bigger isn't automatically better: a 288 Wh station shouldn't lose points for not being a 2 kWh station. The overall WattLab Score therefore measures how good a product is for its size. It's the average of six size-independent sub-scores: charging speed, battery technology, energy density (Wh per pound), solar refill speed (capacity ÷ max solar input), value (Wh per dollar) and versatility (number of outputs plus UPS and app features).
How we score solar panels
Solar panels get their own five-axis scale. Power is the total rated watts (log scale, 50 W → 0 to 1,000 W → 10). Cell efficiency runs from 18% → 0 to 26% → 10. Watts per lb divides one panel's watts by its weight (4 → 0 to 25 → 10). Weatherproofing maps the IP rating (IP68 = 10, IP67 = 9, IP65 = 7.5). Value is watts per dollar at the reference price (0.25 → 0 to 2.0 → 10). The WattLab Panel Score averages efficiency, watts per lb, weatherproofing and value, so a small panel isn't penalized for being small. Complete kits that bundle batteries and an inverter aren't scored on this scale.
Refill estimates on panel pages assume a panel delivers about 75% of its rated watts in good sun, capped at the power station's maximum solar input.
Runtime estimates
Runtime = rated capacity × 85% ÷ device watts. The 85% factor approximates typical inverter and conversion losses for AC loads. Devices that exceed the continuous AC rating are marked "Exceeds inverter". Device loads are typical US figures; check your own appliance's label for precision.
Prices
We show a reference price, the manufacturer's US store price on the date we checked it, so value scores are reproducible. It isn't the Amazon price. Amazon prices change frequently, so always use the "Check Price on Amazon" button for the current price.
Independence
We earn affiliate commissions when you buy through our Amazon links. Commissions never change scores: the formulas above are applied identically to every product.