By Emily ParkerSpec sheets only help when you know which numbers matter. This checklist covers battery capacity, inverter output, solar input, chemistry, charge time, ports, weight, warranty, and app features so you can compare any two portable power stations directly. If you are new to these units, the solar generator buying guides explain the basics first.
Before you start: define the job
List the devices you want to power and how long each one needs to run. Power is measured in watts, and energy is power multiplied by time in hours. A 100-watt device running for 3 hours uses 300 watt-hours. Add up every load to find the minimum capacity you should shop for. The solar generator sizing guide walks through this step in more detail.
One formula appears on every spec sheet: watt-hours equals amp-hours times volts. If a battery lists 50 amp-hours at 12 volts, it stores 600 watt-hours in that example. When two batteries list different voltages, compare watt-hours rather than amp-hours.
The spec-sheet checklist by category
Work through these categories in order, then fill in the comparison template at the end.
Battery capacity and usable energy
Look for capacity stated in watt-hours. Some units show milliamp-hours in fine print; convert by multiplying by voltage and dividing by 1000. Check whether the spec reports total cell energy or usable energy. High discharge rates and cold temperatures can lower real-world capacity, so treat the number as a planning figure.
Inverter output and surge
Continuous output tells you how much alternating current power the unit can sustain. Surge output covers brief starts from inductive loads such as refrigerators and pumps. Compare both numbers with the loads on your list. Check whether the output is pure sine wave; sensitive electronics generally prefer that waveform. The shape matters more than the marketing language around it.
Inverter efficiency is usually not on the sheet, but a common planning assumption is 85 to 90 percent. To size this, divide your AC load by the efficiency. At 90 percent, a 100-watt load draws about 111 watts from the battery; at 85 percent it draws about 118 watts. That margin matters when you estimate runtime.
Battery chemistry and cycle rating
Chemistry affects lifespan and weight. Common chemistries include lithium iron phosphate, often called LFP, and nickel manganese cobalt, sometimes called NMC. LFP units usually hold many more cycles but weigh more; NMC units tend to be more compact. Compare the cycle rating instead of just the chemistry name. Check what depth of discharge the rating assumes.
Solar input voltage and watts
The maximum solar wattage tells you how much panel power the charge controller can accept. The maximum input voltage tells you how many panels you can wire in series. The controller also has a startup voltage and a working voltage range. Panels must stay inside that range, and the voltage limit must never be exceeded. Check the connector type as well, so your panel cable will fit. When in doubt, read the manual before connecting any panel.
Charge time from AC and solar
Manufacturer charge times assume specific conditions. AC charging is usually the fastest, but the actual input depends on the wall outlet and the internal charger. Solar charging depends on sunlight, panel angle, and controller losses. A simple estimate is battery capacity divided by solar wattage, plus a loss factor. For example, a 1200 watt-hour battery with 200 watts of panels is 1200 divided by 200, or 6 hours in perfect conditions. Realistic time will be longer, so label every number as an estimate when you compare.
Ports and output types
Count the ports you actually need: AC outlets, USB-C, USB-A, and 12-volt outputs. For USB-C, check the wattage rating. For AC outlets, look at the total continuous output. Also note whether the AC outlet shape matches your plugs. The right port mix prevents adapter clutter, but it does not replace the capacity calculation.
Weight and portability
Weight on the spec sheet is the unit without panels unless stated. Compare the total weight and the handle design. A heavy unit with a well-designed handle can be easier to move than a lighter unit with an awkward grip. Check the shape against your storage space and vehicle. The spec sheet is the reliable source here, not product photos.
Warranty and support
Compare warranty length, what it covers, and the claim process. Coverage may include the battery, inverter, and accessories separately. Some warranties require registration within a short period. Read the support page or the manual before you buy, because a warranty is only useful when the process is realistic.
App and monitoring
App connectivity is a convenience, not a core spec. Look for an app that reports state of charge, live input power, and live output power. Useful apps may also set charge limits and update firmware. Check whether the app needs an internet connection for basic monitoring. Decide whether that level of control matters for your camping, emergency, or off-grid use.
What you can skip
Not every number deserves equal attention. Skip vague claims such as “powers most appliances” unless the continuous wattage supports it. Ignore surge ratings far beyond any load you own. Skip port types you will never use, and ignore car charging input if you never charge from a vehicle. Extra features such as built-in lights or displays are pleasant but do not change the energy math. For a broader method of weighing trade-offs, see the guide to choosing a portable solar generator.
Comparison table template
Copy this structure into a notebook or spreadsheet. Enter each spec in its own row so you can compare candidates side by side.
| What to compare | What to check | Candidate 1 | Candidate 2 | Candidate 3 |
|---|---|---|---|---|
| Battery capacity | Capacity in watt-hours | — | — | — |
| Inverter output | Continuous AC watts | — | — | — |
| Surge output | Peak AC watts and stated duration | — | — | — |
| Solar input | Max watts, max voltage, connector | — | — | — |
| AC charge time | Input watts and rated hours | — | — | — |
| Solar charge time | Input watts and rated hours | — | — | — |
| Battery chemistry | Cell type and minimum cycle rating | — | — | — |
| Ports | AC outlets, USB-C watts, USB-A, 12V | — | — | — |
| Weight | Total pounds or kilograms | — | — | — |
| Warranty | Duration, coverage, claim process | — | — | — |
| App | What it shows and connection needs | — | — | — |
How to apply the checklist
Fill one row per candidate using the spec sheet, not the marketing page. Note any assumptions in a separate column: solar irradiance, discharge depth, or efficiency. If one unit has more capacity but lower surge, decide which factor your load list rewards. If you rely on solar, the solar input range matters more than fast AC charging. For a useful starting list, the best solar generators guide can point you toward categories worth comparing. You can use the same template when you compare solar generators from different manufacturers side by side. Once the checklist narrows your options, read the manufacturer’s manual for exact charging and safety details.
FAQ
Should I compare amp-hours or watt-hours?
Always compare watt-hours. Amp-hours only make sense at the same voltage, so convert: watt-hours equals amp-hours times volts. A 100 amp-hour battery at 12 volts stores 1200 watt-hours; the same 100 amp-hours at 24 volts would be 2400 watt-hours. The two figures are not directly comparable without the voltage.
What if the surge rating seems too low?
Surge ratings are short-term capabilities. Check the surge duration: some units hold it for a few seconds and others longer. For motors and compressors, the starting surge must be available long enough to spin the device up. If the surge looks marginal for your largest load, choose a unit with more headroom.
Why does solar input voltage matter so much?
Because the charger expects a specific voltage range. Exceeding the maximum can damage the unit, and too little voltage may keep the charger from starting. Panels wired in series increase voltage; panels wired in parallel increase current. Choose panels using the manual’s limits, not just the wattage rating.
How should I interpret a manufacturer’s charge time?
Treat it as an estimate for a defined condition. Solar charge time especially depends on sun intensity and panel angle. Recalculate using your own panels and add a loss margin for controller and wiring losses. Real-world time almost always exceeds the ideal calculation.
A spec sheet checklist turns a confusing list of numbers into a clear trade-off table. Work through capacity, output, surge, solar input, charge time, ports, weight, warranty, and app features in that order, and write down the assumptions you used. When you compare solar generators this way, the best choice for your situation becomes obvious without falling for marketing language.
About Emily Parker
Emily Parker is part of our editorial team and reviews and edits our solar generators for home backup & emergencies guides, checking product details against manufacturer specifications and owner feedback.
