EN / FR
home

Portable Power Stations for EU Homes: Sizing for Blackouts and the Specs That Matter

Watt-hours decide how long, watts decide what you can run at all, and the two are not interchangeable. A specs-first guide to sizing a portable power station for EU blackouts and camping.

christophe

— 8 min read

A portable power station is a big rechargeable battery with sockets on the front. In a blackout it can keep the router alive, charge phones and laptops, run a few lights, and in some cases hold a fridge over a short cut. Unlike a petrol generator it makes no fumes and almost no noise, so it can be used indoors. The hard part is not deciding that you want one. It is reading the specs well enough to buy the right size, because the wrong size either fails to start your appliances or costs far more than your actual needs.

This guide is a decision framework for a European household, whether the goal is blackout backup or camping power. It is about the numbers that matter and how they relate to each other, not about any specific product.

The two numbers that decide everything: watt-hours and watts

Almost every sizing mistake comes from confusing two specs that sound similar and mean completely different things.

Capacity is measured in watt-hours (Wh). It is how much total energy the battery holds, and it decides how long the station can run a given load. Output is measured in watts (W). It is how much power the station can deliver at one instant, and it decides what you can plug in at all. A plain way to hold the two apart: watt-hours are how big the fuel tank is, watts are how wide the fuel pipe is. A unit with a 2,000W output and only 500Wh of capacity can start a 2,000W appliance but will empty in roughly a quarter of an hour. A unit with 500W output and 2,000Wh of capacity will run a 100W device for many hours but cannot power a 1,500W kettle at all, because the load is wider than the pipe.

So you read the two numbers in order. First check that the station's continuous output in watts is higher than the running wattage of the thing you want to power. Only then use the watt-hours to estimate how long it will last.

Surge versus continuous output

There is a second output number that catches people out. Anything with a motor or compressor, a fridge being the classic home example, draws a brief spike of power at the moment it starts, often two to three times its running wattage for a second or two. Manufacturers list this as surge or peak watts, separate from the continuous rating. If the surge demand is higher than the station can momentarily supply, the station trips and the appliance never starts, even though the running wattage was comfortably inside the continuous figure. For lights, routers, and laptops this rarely matters. For a fridge, a pump, or a power tool, you size against the surge number, not just the steady one.

What a given size can realistically run

This is where the watt-hours math becomes concrete, and you can do it for your own home without trusting any product's marketing. The method is device wattage multiplied by hours. A device drawing 60W for five hours uses about 300Wh. In the real world the inverter and conversion losses mean you should not expect to extract the full nameplate capacity, so a common rule is to multiply by roughly 0.85 to estimate usable runtime rather than assuming a perfect figure.

Group your devices by how hungry they are, because that grouping is what determines the size you need. Low-draw electronics are the easy, long-running category: a wifi router pulls only a handful of watts, a laptop somewhere in the tens of watts, LED lights a few watts each, a phone charger barely registers. A modest power station can keep that whole communications-and-light cluster going for many hours or across a night, which for most short EU blackouts is the real job.

Heating with electricity is the opposite category. A kettle, a toaster, an electric hob, a hair dryer, or a fan heater can each draw on the order of one to three kilowatts. That demand is wide enough to need a high-output station, and because the draw is so large it drains capacity in minutes rather than hours. Treat resistive heating as the thing portable power stations are worst at.

The fridge sits in between and deserves honest framing. A domestic fridge does not run continuously, it cycles, so its average energy use over a day is far lower than its running wattage suggests, but it has that startup surge to clear. A mid-sized station with adequate surge headroom can often nurse a fridge through a blackout of a few hours, but it is not a calculation to guess at. Read the appliance's own label and size against both its surge and its daily energy.

Battery chemistry: why LiFePO4 has become the default

Two lithium chemistries dominate these products, and the difference is worth understanding because it affects how long the unit lasts and how safe it is sitting in your home.

Older and cheaper units often use a nickel-based lithium chemistry, commonly NMC. Newer ones increasingly use lithium iron phosphate, written LiFePO4 or LFP. The headline advantage of LiFePO4 is cycle life. Where conventional lithium-ion cells are often rated for a few hundred to perhaps a thousand full charge cycles before fading, LiFePO4 cells are commonly rated for several thousand. Manufacturer specifications for current LiFePO4 power stations cluster in the range of roughly 2,500 to 4,000 cycles, and sometimes higher, before capacity falls to about 80 percent of the original. One maker rates its LiFePO4 packs at over 3,000 cycles to the 80 percent point. In practical terms a unit charged weekly can last many years before its capacity noticeably drops.

The second advantage is safety. LiFePO4 is more thermally stable than nickel-rich chemistries. The iron phosphate cathode resists releasing oxygen when it gets hot, which is the reaction that feeds a runaway fire, and its thermal runaway onset temperature is far higher than that of cobalt or nickel-based cells. No lithium battery is immune to abuse, and overcharging, deep physical damage, or extreme heat can still cause problems, but for a battery that lives indoors and may sit on standby for months, the more stable chemistry is the sensible default.

Pure sine wave, not modified

The inverter inside the station turns the battery's direct current into the alternating current your sockets expect, and the shape of that alternating current matters. A pure sine wave is the smooth waveform the grid delivers. A modified sine wave is a cheaper, blockier approximation. Simple resistive loads tolerate the modified shape, but modern electronics with switched-mode power supplies, laptops, medical devices such as CPAP machines, and some motors, can run hotter, buzz, misbehave, or in the worst case be damaged on a modified waveform. For a station whose whole point is keeping sensitive electronics alive, a pure sine wave output is the specification to insist on. Most reputable home units now provide it, but it is worth confirming rather than assuming.

Recharge paths: mains, solar, and car

A power station is only as useful as your ability to refill it, and there are three common paths. Mains charging from a wall socket is the fastest and the one you will use most, topping the unit back up between events. Solar charging, using portable panels, is what turns the station from a one-shot battery into something that can ride out a longer outage or a multi-day camp, provided you have sun and the panel wattage to make meaningful progress in a day. Car charging from the 12V socket is the slowest of the three and is best thought of as a trickle top-up while driving rather than a primary method. When comparing units, check the maximum input each path accepts, because that sets how quickly you can recover.

EU voltage, plugs, and pass-through

Buy for the grid you actually have. Continental European mains is harmonised at 230 volts, 50 hertz, under the CENELEC standard, with a tolerance band around that nominal value. A station sold for the North American 120-volt, 60-hertz market is the wrong appliance, so confirm the unit outputs 230V at 50Hz and carries the right socket type for your country. Many stations also offer pass-through, charging from the wall while simultaneously powering your devices, which lets the unit sit inline like an uninterruptible supply. Pass-through is convenient, but check the manufacturer's guidance, as continuous charge-and-discharge is not ideal for every unit and some advise against running it permanently that way.

The real safety case: why this beats a petrol generator indoors

The single biggest practical advantage of a battery power station is that it is safe to use inside. A petrol or diesel generator is not. Engine exhaust contains carbon monoxide, a poison you cannot see or smell, and the US Consumer Product Safety Commission is unambiguous that portable generators must never be used indoors or in garages, basements, or sheds, and should run outside well away from windows, doors, and vents. The agency notes that a single portable generator can produce as much carbon monoxide as hundreds of cars, that opening doors and windows does not provide enough ventilation to prevent lethal buildup, and that on the order of a hundred people die each year in the United States from generator carbon monoxide. A battery power station produces no combustion gases at all, which is precisely why it can run your essentials indoors through a blackout. That single difference, more than any spec, is why these units have become the default home backup for people who want power indoors safely.

Size it with the two numbers first, output then capacity, confirm the surge headroom for anything with a motor, prefer LiFePO4 and a pure sine wave, and match it to a 230V European grid. Do that and you buy a unit that fits the blackout you are likely to have, not the one on the box.

This article is independent analysis by House of Agile. It reflects public energy and safety guidance, manufacturer technical documentation, and general electrical principles, not professional electrical or purchasing advice. Verify the capacity, output, surge rating, and certifications of any specific unit, and read its manual, before buying or relying on it.

Sources

Safety bodies

Standards and grid

Battery chemistry and manufacturer technical pages

Sizing and inverter waveform

Read more