The power station math nobody does before buying one

Two numbers decide whether a portable power station is useful to you. Watt-hours, which is how much energy it holds. And watts, which is how much it can push out at once. Almost every disappointing purchase comes from buying enough of one and not enough of the other.

Start with your refrigerator, because that's the thing most people are actually trying to save. A full-size modern fridge pulls something like 1 to 1.5 kilowatt-hours over a full day. It isn't drawing that constantly. The compressor kicks on at maybe 120 to 150 watts, runs for a while, shuts off. Average it out and you're looking at 40 to 60 watts around the clock. So a 1,000Wh unit runs your fridge for most of a day and then it's empty. A 2,000Wh unit gets you through a day and a half and nothing else.

That's the first ugly bit of arithmetic. Write it down before you shop.

Do the audit, and be honest about it

Walk the house with a notepad. List what you genuinely need powered during an outage, not what would be nice.

For most families it's a short list. Fridge. Phones and a laptop. A few lamps. Maybe a modem and router, which together sip 15 to 25 watts and will run for days off almost anything. Possibly a CPAP, which is the one medical-adjacent item worth planning around carefully.

A CPAP without the heated humidifier typically draws 30 to 60 watts and might use 300 to 400 watt-hours over a night. Turn the humidifier on and that can double or worse. If someone in your house depends on one, check the label on the unit and talk to the supplier about the DC cable, which skips the inverter losses and saves you meaningful capacity.

Now add up the daily watt-hours. Fridge at 1,200. CPAP at 400. Phones, tablet, laptop, lights at maybe 300. You're at roughly 1,900 watt-hours a day for a pretty modest setup.

What won't run, no matter what the box says

Anything that makes heat is the enemy. Resistive heating is brutally inefficient in energy terms and there's no clever way around it.

An electric kettle is 1,500 watts. A hair dryer, a space heater, a toaster, a coffee maker, a microwave. All in the same range. A 1,500W load on a 2,000Wh battery drains it in about eighty minutes of actual run time, and that's before inverter losses.

You can boil one kettle. You can't heat a room.

Well pumps, sump pumps and anything with a big induction motor are a separate problem. They surge hard on startup, often three to six times their running wattage. A pump rated at 800 watts running can demand 3,000 or more for a fraction of a second. If the inverter can't cover that surge it trips, and you've got a dead pump and a basement filling up. Check the surge rating, not just the continuous rating, and check the pump's locked-rotor amps on its plate.

Sizing for two very different jobs

Camping. You want light, and you want it to survive being thrown in a truck bed. For a weekend with phones, a camera, some lights and a fan, 300 to 500Wh is plenty and weighs under fifteen pounds. Add a 12V portable fridge and you want 1,000Wh plus a solar panel, because those fridges draw 30 to 45 watts on and off all day and they don't stop just because the sun went down.

Home outage. You want capacity, and weight matters less because it's going to sit in one place. From that audit above, 2,000Wh covers about a day. If you want three days without sun, you'd need 6,000Wh, which is a lot of money and a lot of lithium.

So most people go a different route: a 2,000Wh unit plus enough solar to refill it daily. That changes the question from "how big a battery" to "how fast can I put energy back in".

Solar is slower than the marketing suggests

A 100W panel doesn't make 100 watts. In good summer sun, angled properly, you might get 400 to 500 watt-hours out of it across a day. In December, under cloud, in the northern half of the country, you could get a fifth of that.

To replace 1,900 watt-hours daily in fair conditions you want 400 to 600 watts of panel. That's four to six full-size portable panels, and they need somewhere to sit where nothing shades them. One tree branch across a panel can knock the output down disproportionately.

Charging off your car's 12V socket is the backup people forget. It works, and it's slow. Most sockets are fused around 10 to 15 amps, so you're limited to roughly 100 to 180 watts. Call it ten hours of idling to put a kilowatt-hour back. Some newer stations charge off a car's alternator at much higher rates with the right cable. Worth asking about.

LiFePO4 versus the older chemistry

Lithium iron phosphate is what you want for a unit that sits in a closet for years. It handles far more charge cycles than the NMC chemistry that older stations used, and it's more tolerant of being left sitting. It's heavier for the same capacity, which is why a few ultralight camping units still use NMC.

Expect a 2,000Wh LiFePO4 station to weigh somewhere around 45 to 60 pounds. That's a two-handed lift with a real handle, not something you carry to a campsite one-handed.

Cold matters too. Most lithium packs refuse to charge below freezing, and the good ones have a heater built in to handle it. If your station lives in an unheated garage in Minnesota, that feature isn't optional.

The features that earn their keep

Pure sine wave inverter. Non-negotiable for anything with a motor or sensitive electronics. Most decent units have it. Confirm anyway.

UPS pass-through. The station sits between the wall and your gear, and when grid power drops it takes over in 10 to 20 milliseconds. Your desktop doesn't reboot. Your CPAP doesn't stop. This is the single most useful feature for a home office and it's easy to miss on a spec sheet.

Expandable battery ports. Buy 2,000Wh now, bolt on more later if you find you need it. Cheaper than buying twice.

Actual outlet count. Two AC outlets isn't enough when you've got a fridge, a lamp and a power strip going.

What goes wrong after you buy it

People store them full and never touch them. Lithium doesn't love sitting at 100 percent for a year. Aim for 50 to 60 percent in storage and put a reminder in your phone to run it down and top it up every three or four months. You also want to know it actually works before the night you need it.

People also buy the station and forget the extension cord. Your fridge isn't next to your closet. Get a heavy-gauge outdoor cord, 12 or 14 AWG, long enough to reach, and store it with the unit along with the solar cables and the car charging lead. One box, one place.

And the honest concession: if you're regularly losing power for three or four days, a propane or dual-fuel generator is the better tool for the money. It's louder, it needs fuel, it lives outside and it will kill you if you run it in the garage. But it makes power indefinitely, and a battery only ever gives back what you put in.

Buy the battery for quiet, for indoors, and for the first thirty-six hours. Know which problem you're solving before you spend.