Best Generators for Home Backup UK 2026

Storm-driven power cuts have become a routine part of a British winter, and a backup generator is the difference between an inconvenience and a freezer full of spoiled food. These are the five generators we rate for UK home backup, judged on output, runtime, noise and how easily they slot into a real household setup.

What size generator do you need?

Work from the appliances you actually need running, not the size of your house. A fridge-freezer, boiler, router, a few lights and phone charging comes to roughly 1.5–2.5 kW of continuous load — comfortably inside a 3 kW generator. Add an electric shower, kettle or immersion heater and you are into 5 kW or more.

Watch the difference between running watts and starting watts. Motors in fridges, freezers, pumps and boilers draw two to three times their running figure for a second or two at start-up. Size to the largest starting surge, or the generator will trip every time the freezer cycles.

Petrol, diesel or dual fuel?

Petrol is cheapest to buy, easy to source and fine for occasional use, but the fuel goes stale in months. Dual fuel units run on petrol or LPG, and bottled gas stores indefinitely — a genuine advantage for a machine that might sit unused for two years between outages. Diesel costs more up front but is the choice if you need long runtimes or expect frequent use.

Inverter or conventional?

An inverter generator produces clean, stable sine wave power safe for laptops, TVs, modern boilers and anything with a circuit board, and it throttles down under light load so it is far quieter and more economical. A conventional open-frame generator gives more raw watts per pound but produces dirtier power and runs flat out regardless of demand. For home backup, an inverter is almost always the better answer.

Connecting a generator safely

Never plug a generator into a wall socket to feed the house. Backfeeding is illegal, and it puts lethal voltage onto the network for anyone working on the line. The safe options are running appliances directly from the generator on heavy-duty extension leads, or having a qualified electrician fit a manual changeover switch or interlock so the property is isolated from the grid before the generator is connected.

Generators must always be run outdoors, well clear of doors, windows and air bricks. Carbon monoxide from a generator in a garage or porch kills people in the UK every year.

Runtime and running costs

Manufacturer runtime figures are quoted at 25–50% load — expect noticeably less at full output. For overnight cover, look for at least 8 hours at half load, and check tank capacity rather than trusting the headline hours. A 3 kW inverter running a fridge, lights and a boiler typically burns under a litre of petrol an hour.