Portable power station shopping hinges on two separate specs that are easy to conflate but answer completely different questions.
Watt-hours (capacity) vs. watts (output)
Watt-hours (Wh) measure total stored energy — how much power the unit holds overall, comparable to a fuel tank's size. Watts (W), specifically the continuous and surge/peak output ratings, measure how much power the unit can deliver at any given moment — comparable to how fast fuel can flow out of that tank. A power station can have a large watt-hour capacity but a limited continuous watt output, meaning it can run a low-power device for a long time but genuinely cannot power something that draws more watts than its output rating, regardless of how much total capacity remains in the battery. Checking both numbers against actual intended use — not just the more prominently marketed capacity figure — avoids buying a unit that can't actually run the specific device intended.
Surge watts matter for motors and compressors
Devices with a motor or compressor — refrigerators, power tools, air conditioners — draw a brief surge of power meaningfully higher than their steady running wattage at the moment they start up. A power station's continuous watt rating might be sufficient for a device's ongoing operation, but if its surge/peak rating is too low, the device may fail to start at all. Checking a specific appliance's startup surge requirement, not just its running wattage, matters especially for anything with a motor.
Solar charging capability depends on more than just having an input
Many portable power stations support solar panel charging, but actual charging speed depends on the panel's wattage, sunlight conditions, and the power station's maximum solar input rate — a mismatch between a large power station and undersized solar panels means slow real-world recharging regardless of the station's solar-compatible marketing. For anyone planning to rely on solar charging specifically (extended off-grid use, emergency preparedness), matching panel wattage to the power station's actual maximum solar input capacity is worth checking rather than assuming any solar panel works equally well.
Battery chemistry affects longevity and safety profile
Lithium iron phosphate (LFP/LiFePO4) batteries generally offer a longer cycle life and are considered to have a more stable safety profile than older lithium-ion chemistries, at the cost of being somewhat heavier and bulkier for the same capacity. For a power station expected to see frequent, regular charge cycles over years of use, this longevity difference can be a meaningful factor beyond the initial capacity and price comparison.
The one thing people forget
Check the unit's actual recharge time from empty, both via wall outlet and via car charging or solar, before assuming a large-capacity unit is always the better choice. A bigger battery that takes considerably longer to recharge can be less practical for regular use than a smaller unit that charges quickly, depending on how the power station will actually be used and how often it needs to be topped up.