Power outages don't just turn off the lights. When the grid goes down for hours or days, food spoils, internet vanishes, heating stops, and daily life grinds to a halt. In Europe, extreme weather events are becoming more frequent – from flooding in Germany to heatwaves in the Mediterranean. Grid reliability is no longer something you can take for granted.
But what size battery does your home really need? This guide walks you through how to calculate your actual power requirements, which appliances matter most, and how Purmars off‑grid storage systems (5 kW to 30 kW) provide a clean, silent and reliable backup solution – whether you are in the UK, Germany, France, or anywhere else in Europe.
Quick Answer
List all the devices you want to keep running during an outage. Add their running watts and account for starting surges. Then add a safety margin.
| Backup Goal | Typical Power | Recommended Purmars Model |
|---|---|---|
| Essentials only (fridge, lights, router, phone) | 3 000–5 000 W | Purmars 5 kW |
| Extended comfort (+ freezer, microwave, pump, home office) | 6 000–10 000 W | Purmars 10 kW |
| Partial home (+ heat pump, well pump, multiple appliances) | 10 000–15 000 W | Purmars 15 kW |
| Whole‑home backup (HVAC, electric cooking, EV charging) | 15 000–25 000 W+ | Purmars 20 kW – 30 kW |
A typical UK household consumes around 8–10 kWh per day. For essential backup, 5–15 kWh usable capacity is often enough; for full operation or off‑grid living, 20–30 kWh or more is advisable.
Why Getting the Size Right Matters
Too small – and you are left in the dark. If the battery cannot handle the combined load of your appliances – especially the startup surge of a refrigerator compressor or a heat pump – it will trip. In a European winter, that often means no heating; in summer, no cooling.
Too large – and you are wasting money. An oversized system costs more, takes up more space, and burdens the budget. For battery systems, this means paying for capacity you may rarely use – money that could be better spent on additional solar panels or extra features.
The right size depends on your backup strategy. Some want only the bare essentials, others want to maintain most of their daily routine, and some aim for a near‑seamless grid‑like experience. Each goal requires a different power level.
Europe adds its own complexity: homes range from compact Berlin flats to sprawling French farmhouses. The surge in heat pumps, electric vehicles and induction hobs is driving rapid electrification – your backup system must keep pace.
Typical Loads in a European Home
Refrigeration & Freezing
A modern A+++ fridge runs on 150–400 W and peaks at 600–1 200 W when the compressor kicks in. A separate freezer behaves similarly.
Communication & Work
Routers, modems, phones and laptops keep you connected – for work, emergencies and peace of mind. Together they draw 50–200 W, but they are non‑negotiable for many.
Lighting
LED bulbs consume only 50–150 W for the entire home, yet they make a huge difference during a night‑time outage.
Heating & Cooling (European reality)
More and more homes use heat pumps (air‑to‑water) with 2 000–5 000 W running and startup surges that can double that. Electric radiators or underfloor heating are even more demanding. Portable AC units and split systems are also gaining popularity – they draw 1 000–2 500 W.
Water Pumps
For well pumps (common in rural areas), backup is not a luxury. A 1 HP pump needs 1 000–1 500 W running and 2 500–3 500 W surge. Sump pumps for basements have similar values.
Cooking
Induction hobs (1 500–2 500 W per zone) and electric ovens (2 000–4 000 W) are power‑hungry but used intermittently. Plan not to run them all at once.
Electric Vehicles
Charging an EV at 7 kW (Level 2) is a significant continuous load – it must be included in your sizing.
“Phantom” Loads
Smart meters, security cameras, Wi‑Fi speakers and standby devices add 50–150 W around the clock – which adds up over multi‑day outages.
How to Size Your System in 5 Steps
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Decide: essentials‑only or whole‑house? Define what absolutely must run.
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List: write down every appliance you want to back up – with model and type.
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Find running watts: check the label (W). If only amps (A) are given, multiply by 230 V (European voltage).
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Account for startup surges: motor‑ or compressor‑driven devices have a surge (2‑3× running). If several start at once, the peak will be higher.
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Add a 20 % safety margin – for aging, unexpected loads and future expansions.
Purmars Off‑Grid Storage Systems – for Every European Home
Purmars is a Chinese manufacturer with its own production and offers a full range from 5 kW, 10 kW, 15 kW, 20 kW and 30 kW – tailored to every backup goal.
Ideal for flats and small homes. Powers fridge, lights, router, laptop and phone.
For families with freezer, sump pump, microwave and home office.
For air‑to‑water heat pumps, well pumps and medium‑sized houses.
For large homes, EV charging, central heat pump and all appliances simultaneously.
For villas, multiple heat pumps, two EVs or small businesses – a second grid.
Why Purmars?
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Full power range (5–30 kW) – one line for all needs.
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OEM/ODM customisation – from design and software to branding.
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Factory prices – no middlemen, direct savings.
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Integrated quality – cell selection, BMS development and final assembly under strict control.
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Global compatibility – systems for 230 V (single‑phase and three‑phase) per European standards.
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Flexible order quantities – from trial batches to full containers.
Purmars systems are already operating in North America, Europe, the Middle East, Southeast Asia and regions with frequent outages.
Quick Selection Guide
| Your Home Profile | Recommended Model | Typical Supported Loads |
|---|---|---|
| Flat / apartment / basic | 5 kW | Fridge, lights, internet, laptop, phone |
| 2–3‑bedroom house with basement | 10 kW | + freezer, sump pump, microwave, home office |
| With heat pump / well | 15 kW | + heat pump, well pump, portable AC |
| Large home / EV / whole house | 20 kW | Central heat pump, EV charging, full kitchen |
| Villa / multiple EVs | 30 kW | Multiple heat pumps, two EVs, all appliances simultaneously |
FAQ
For essentials, 3 000–5 000 W often suffice. With a heat pump or water pump, 10 000–15 000 W is realistic. For whole‑home, 20 000–30 000 W+.
Yes for basic loads (fridge, lights, router). Not for heat pumps, electric ovens or EV charging.
Heat pumps require 2 000–5 000 W running and up to 10 000 W surge. Recommendation: at least 15 kW, preferably 20 kW+ for simultaneous use.
Power (kW) determines what runs, energy (kWh) determines how long. With a daily consumption of 8–10 kWh, you need at least that much usable capacity for 24 hours. Purmars systems are configurable.
Yes for many loads, especially indoors, being silent and emission‑free. For very long outages, larger systems like 20 kW or 30 kW are better. They can also be recharged by solar panels.
Yes, as a manufacturer we offer full customisation – from hardware to software. Contact us for details.
Purmars – Chinese manufacturer with in‑house production. Specialist in off‑grid home storage. OEM/ODM available. Partners worldwide – from North America, Europe, Middle East to Southeast Asia.
