Choose a power station by checking two separate limits: enough watts to run and start your appliances, and enough watt-hours to keep them running for your target time. Under the explicit example assumptions below, a 1,000Wh station powers a 60W laptop load for about 10.7 hours or a fridge using 1kWh/day for about 14.7 hours—not both simultaneously.
This is a US-focused sizing guide, not a product ranking. The runtime table contains calculated scenarios, not appliance specifications or hands-on test results. Sources checked November 14, 2026. Replace the example inputs with your equipment’s measured energy use and manufacturer limits before buying.
Watts versus watt-hours: check both numbers
Watts (W) describe power at a moment in time. A station’s continuous output rating limits what it can supply at once. Watt-hours (Wh) describe stored energy. A 1,000Wh battery theoretically supplies 100W for ten hours before losses or reserve; real operation includes both.
The University of Maryland’s system-sizing guide explains this distinction and why itemizing loads comes first. More storage does not automatically mean more output power. Two stations with the same Wh can have different inverter ratings and ports.
Also check startup demand. A refrigerator compressor can briefly require more power than it draws while running. Read the station’s continuous rating, surge duration and the appliance’s requirements. A marketing boost mode is not automatically equivalent to ordinary continuous output at normal voltage.
Runtime table: 300Wh versus 1,000Wh versus 2,000Wh
Every row assumes: full charge, stopping at a 20% reserve, 90% AC conversion efficiency, 8W additional inverter draw, one listed load only and no recharging. These are chosen teaching inputs, not universal power-station specifications. All rows use the AC-output path, including a phone’s wall charger.
| Illustrative load | 300Wh | 1,000Wh | 2,000Wh |
|---|---|---|---|
| Fridge: 1kWh/day | 4.4 h | 14.7 h | 29.5 h |
| Phone charger: assumed 10W | 12.6 h | 41.9 h | 83.7 h |
| Laptop: assumed 60W | 3.2 h | 10.7 h | 21.4 h |
| CPAP setup: hypothetical 40W* | 4.6 h | 15.3 h | 30.5 h |
| LED lighting: assumed 10W | 12.6 h | 41.9 h | 83.7 h |
| Fan: assumed 35W | 5.1 h | 17.1 h | 34.1 h |
| TV: hypothetical 80W | 2.5 h | 8.3 h | 16.5 h |
*CPAP row: 40W is a hypothetical measured average, not a typical rating or a claim about any CPAP model. It cannot establish safe overnight coverage. See the CPAP checks below.
The phone row means hours supplying an assumed steady 10W charging load—not hours of phone use or a count of full charges. Real charging tapers and stops. Direct USB or DC operation needs a different loss model and may avoid the AC inverter’s overhead.
Formula: runtime = nominal Wh × 0.80 ÷ [(average AC watts ÷ 0.90) + 8W]. For the laptop row: 1,000 × 0.80 ÷ [(60 ÷ 0.90) + 8] = 10.7 hours.
At tiny loads, inverter overhead matters disproportionately. A different station could use much less or more than the assumed 8W, and an automatic low-load shutdown could interrupt operation. If you have a tested usable-AC-energy figure for a comparable load, divide that by load watts instead; do not subtract the same losses twice.
How to run a TV on a portable power station
Measure your TV in the picture mode you actually watch, then add any streaming box, antenna amplifier or sound system. Confirm that their combined load is within the station’s AC output limit. Connect the TV using the equipment instructions and test a viewing session before relying on it during an outage.
The table assumes an 80W TV, not a universal TV rating. With a 1,000Wh station, the same 20% reserve, 90% inverter efficiency and 8W overhead used above give 800 ÷ (80 ÷ 0.90 + 8) = 8.3 hours. Brightness, screen size, accessories, temperature and the actual station can change the result. Leave capacity for the fridge or communications if those take priority.
Build your own appliance list before choosing capacity
For each item, record average watts or energy per session, hours needed, output-port requirements and startup demand. Use a suitably rated energy meter where permitted, or exact model documentation. A laptop adapter’s maximum rating is not its steady consumption, and a refrigerator’s running watts are not its daily average.
| Illustrative evening setup | Time | Energy delivered to appliances |
|---|---|---|
| Laptop averaging 60W | 4 hours | 240Wh |
| Fan averaging 35W | 4 hours | 140Wh |
| LED lights totaling 10W | 4 hours | 40Wh |
| Total average load: 105W | 4 hours | 420Wh |
Using the same loss assumptions, this setup requires [(105 ÷ 0.90) + 8] × 4 = 498.7Wh from the battery. Keeping a 20% reserve means at least 498.7 ÷ 0.80 = 623.3Wh nominal capacity, before extra allowance for aging, temperature or longer use. That is a mathematical threshold, not a finished purchase recommendation.
Then verify simultaneous output and ports. The inverter must support the actual combined load and any startup event; USB-C ports must provide the power profile your laptop requires. Check shared port limits, not just the largest number printed beside one outlet.
Fridge example: why “100Ah lasts 19 hours” needs context
Our refrigerator battery runtime calculator includes a reproducible example: a 12.8V, 100Ah battery, starting full with a 20% reserve, supplying a fridge using 1kWh/day through an assumed 90%-efficient inverter with 8W additional draw.
Available battery energy: 12.8 × 100 × 0.80 = 1,024Wh.
Average fridge demand: 1,000 ÷ 24 = 41.67W.
Battery draw: 41.67 ÷ 0.90 + 8 = 54.30W.
Runtime: 1,024 ÷ 54.30 = 18.9 hours.
This battery contains 1,280Wh nominal energy, so it is not equivalent to a 1,000Wh station. Ah alone is insufficient without voltage. A hotter room, frequent door openings, defrost cycles or a partly charged battery can change runtime. Start with our guide to measuring refrigerator kWh per day.
The 41.67W average is an energy-planning input, not the output rating needed to start the compressor. Verify startup compatibility separately. Runtime is also not a prediction of food temperature; keep food-safety decisions separate from battery calculations.
CPAP backup: verify the exact setup first
CPAP energy use depends on the device, operating settings, humidifier and heated tubing. Confirm the approved battery or converter route with the manufacturer and your equipment provider. Do not change prescribed therapy settings to make a small battery last longer.
ResMed’s Air11 converter documentation, for example, specifies a converter for AirSense 11 and suitable 12V or 24V sources. That does not mean any power station’s car-style socket is sufficient or any adapter is acceptable. Check voltage, current, connector and compatibility for your exact model and region.
Plan and test backup with your provider before an outage. Check automatic shutoff, transfer behavior and runtime under your normal setup. A generic power station is not automatically an approved medical backup or an uninterrupted supply. Do not apply the table to a ventilator or other life-support equipment.
Solar recharging: replace daily energy, not just battery size
A panel’s watt rating is not an all-day charging promise. Use location- and season-specific solar resource, shading and the charging system’s limits. Illustrative example: a 200W array × four peak-sun-hours × an assumed 80% panel-to-stored-energy factor = 640Wh stored per day, before subtracting loads operating during charging.
That would exceed the 498.7Wh evening demand above under those assumptions, leaving about 141Wh. At two peak-sun-hours, it yields only 320Wh and falls short. These scenarios demonstrate the energy balance; they do not predict tomorrow’s weather. See our 200W panel and 100Ah battery example and panel tilt calculator.
Check input voltage, current, wattage and approved connectors before pairing panels with a station. For example, the EcoFlow DELTA 2 Max manual lists separate solar-input limits and shared DC-output limits. These are model-specific; matching a plug shape is not sufficient. Follow the exact manual rather than improvising panel wiring.
The purchase checklist that prevents sizing mistakes
Compare nominal Wh, documented usable output at your load, continuous W, surge duration, required ports, reserve settings and low-load shutoff. Also check charging time, allowed simultaneous charging and discharge, operating temperature, ventilation, carry weight and warranty terms.
Keep the unit dry and use it within its instructions. Power plug-in appliances through approved connections. Never connect a portable station to household wiring through an ordinary wall outlet; supplying home circuits requires equipment designed for that purpose and a qualified installation.
Quick answers
Is 300Wh enough? It may cover short, modest loads. Under our assumptions it runs the 60W laptop scenario for 3.2 hours, but capacity alone cannot confirm appliance compatibility.
Is 2,000Wh enough for a whole house? That label alone cannot answer it. Use our whole-home backup checklist to separate supported circuits, peak power and duration.
Does a bigger inverter extend runtime? No. More output capacity can support a larger load, but stored energy and losses determine duration.
The short version
List your loads, calculate their energy, account for reserve and losses, then check startup and port compatibility. Choose enough capacity for your real use and a recharge plan for the next day. Validate the setup before relying on it during an outage.
If your appliance list outgrows a portable unit, compare a power station, installed home battery and generator by outage length, recharge options and critical loads.
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