LPG Generator for Home Backup and Off-Grid Use: The Complete UK Buying Guide

Last updated: May 2026

In 30 seconds:

• Home backup — Greengear 3kW (essentials only) or 5kW (whole-house basics)
• Off-grid living, narrowboats, caravans — Greengear 5kW handles most setups
• Rural property with electric heating or borehole pump — Greengear 7kW

Not sure which? Use our LPG generator sizing calculator. It takes 2 minutes and works for home, off-grid, and mobile catering setups. Why LPG over petrol or diesel? LPG (propane) stores indefinitely in a sealed cylinder. Petrol degrades within months — bad news for a generator that may sit unused for a year between outages. Propane is also cleaner-burning, quieter, and produces no carbon soot. Why Greengear? Greengear is the only “dedicated LPG” generator brand sold in the UK. Every other LPG generator is a petrol engine with an LPG kit added on. Greengear builds the engine for propane from the start — better fuel economy, full rated power, longer engine life. The brand is made in Brescia, Italy by the Cavagna Group. Cavagna has been making LPG parts — valves, regulators, hoses — for 70 years. Greengear is their generator brand. The engines use the ENERKIT BASIC LPG management system, jointly engineered by Greengear and Cavagna for propane combustion. Two more trust signals worth knowing:

• Greengear partnered with the United Nations on clean-fuel projects
• Greengear sent LPG generators to Brazilian hospitals during the 2020 COVID response

The honest summary Most buyers oversize their generator “to be safe” and waste fuel for years. This guide tells you what each Greengear actually runs, what it costs per hour, and how to pick one without guessing.

Why Choose an LPG Generator Over Petrol or Diesel?

Petrol generators are cheap to buy but expensive to live with. Petrol goes stale within 3–6 months, gums up carburettors, and leaves you with a machine that won’t start when you actually need it. Diesel generators last longer but they’re heavy, noisy, and expensive — overkill for most home setups. LPG (propane) solves the biggest problem with home backup generators: you never use them until you need them, and when you need them, the fuel has to work. Propane doesn’t degrade. A cylinder you filled five years ago will run a generator exactly as well as a fresh one. That alone makes it the obvious choice for standby power. The other advantages stack up quickly:

Dual fuel generators — which run on both petrol and LPG — give you the best of both worlds. You can run on propane day-to-day and keep petrol as a backup fuel if your LPG runs out. Every generator MobCater sells is either dedicated LPG or dual fuel.

What Size LPG Generator Do You Need for a Home?

This is where most people either massively overspend or dangerously undersize. The answer depends on what you want to keep running during a power cut — not your total household consumption. Start by listing the essentials. Here’s a realistic UK home backup scenario:

For this scenario, a 3,000W–3,500W generator handles everything comfortably, including the microwave surge. If you add an electric kettle (2,000–3,000W) or immersion heater, you’ll need to step up to 5,000W+. The key rules for sizing:

• Running watts = what the appliance draws continuously
• Starting watts = the surge when a motor kicks in (fridges, pumps, compressors — typically 2–3× running watts)
• Your generator’s rated (continuous) output must exceed your total running watts
• Your generator’s peak output must handle the highest starting surge
• Never run a generator above 75% of rated capacity for extended periods — it shortens engine life and wastes fuel

Best LPG Generators for Home Backup and Off-Grid Use

MobCater stocks generators from 2kW to 12.8kW, all capable of running on LPG. Here’s how they map to common home and off-grid scenarios:

For most UK homes that just need the essentials running during a power cut, the Champion Atom Fusion or GP3500i hits the sweet spot — enough power for heating controls, fridge, lighting, and a microwave, at a noise level that won’t get your neighbours complaining. If you want to run a kettle or portable heater too, step up to the GP5500E-DF.

Off-Grid Use: Caravans, Narrowboats, and Rural Properties

Home backup is one use case. The other big market for LPG generators is people who live or work off-grid permanently or semi-permanently. The requirements are different because you’re running the generator daily, not just during emergencies.

Static Caravans and Holiday Lets

Most static caravans already run on propane for heating and cooking. Adding an LPG generator means one fuel source for everything. A 3,000–3,500W inverter generator (GP3500i or Champion Atom Fusion) handles lighting, fridge, TV, heating controls, and phone charging. The key requirement is clean power — inverter generators produce a pure sine wave that’s safe for electronics, which conventional generators don’t.

Narrowboats and Liveaboards

Space and weight matter on a boat. The GP2000i (22kg) or Champion Atom Fusion (27.7kg) are popular choices because they’re compact and can be mounted in a cockpit locker or stern deck. Many boaters already carry propane for cooking, so adding a dual fuel generator that runs on the same supply makes sense. Watch the ventilation — generators must NEVER run in an enclosed space. CO kills in minutes.

Rural and Agricultural Properties

If you’re on a farm or rural property where power cuts regularly last 6–12 hours, you need a larger unit that can run all day. The GP5500E-DF or GP6500E-DF dual fuel models handle continuous loads well and have large fuel tanks (25 litres petrol). On LPG, a standard 47kg propane cylinder will run a 5kW generator at 75% load for approximately 12–15 hours — enough for a full day.

Shepherd’s Huts, Glamping, and Garden Offices

Low power requirements (lighting, laptop, phone, maybe a small heater) mean a 2,000W inverter generator is plenty. The GP2000i is near-silent at 58 dB and light enough to carry with one hand. For glamping sites, noise matters more than power — your guests won’t thank you for a roaring diesel set at 6am.

LPG Generator Running Costs

Propane costs roughly 65–80p per litre in the UK (bulk delivery is cheaper; bottled gas from a forecourt is more expensive). Here’s what that translates to in generator running costs:

At 75p/litre (roughly £1.46/kg for propane at 1.96 litres per kg), a 3,500W generator running 4 hours during a power cut costs about £3.44. Compare that to the cost of a fridge full of spoiled food (easily £100+), and the economics are obvious. For off-grid daily use, a 47kg propane cylinder costs around £40–60 delivered. At 75% load on a 3,500W generator, that’s roughly 42 hours of running time — about 5 days if you run it 8 hours daily. Budget £40–50 per week for propane if you’re running a generator as your primary power source.

Installation, Safety, and Legal Requirements

LPG generators are straightforward to set up but there are safety rules you must follow. Carbon monoxide from generator exhaust is lethal — every year, people die from running generators in enclosed spaces.

Placement Rules

• ALWAYS outdoors, at least 3 metres from any window, door, or vent
• Under a canopy or generator cover — not in a shed or garage
• On a firm, level surface — concrete slab or paving
• Dry ground with drainage — generators and standing water don’t mix

LPG Connection

• Use a proper LPG regulator set to 37 mbar (UK standard for propane appliances)
• Copper or armoured rubber hose rated for LPG — never PVC or garden hose
• Check all connections with leak detection spray before every use
• The propane cylinder must stand upright and be at least 1 metre from the generator exhaust

Electrical Connection

• Never back-feed into your house mains — this is illegal and can electrocute utility workers
• Use extension leads rated for the generator’s output (13A for loads up to 3kW, 16A or 32A commando for larger)
• For permanent home backup, a qualified electrician can install a transfer switch (also called a changeover switch) that safely isolates your home from the grid when running on generator power
• An RCD (residual current device) must protect all circuits supplied by the generator

Regulations

There’s no UK law preventing you from owning or running a home generator. However:

• Noise — local council noise nuisance rules apply. Keep it below 65 dB at your boundary
• Planning — permanent installations with concrete bases or enclosures may need planning permission
• Insurance — tell your home insurer you have a generator. Some policies exclude damage from generator use if not declared
• Gas Safe — if you’re connecting an LPG generator to a fixed propane supply (bulk tank or piped system), the installation must be done by a Gas Safe registered engineer

Maintenance: Keeping Your LPG Generator Ready

The whole point of an LPG standby generator is that it starts when you need it. That only works if you maintain it properly. LPG engines need less maintenance than petrol, but they’re not maintenance-free.

The single most common reason a standby generator fails to start is a dead battery (electric start models) or stale petrol in the carburettor (dual fuel models left on the petrol setting). If you’re only using yours for emergencies, switch to LPG mode before storing it and run the petrol side dry. That way the carb stays clean and the LPG is always ready.

Inverter vs Conventional: Which Type for Home Use?

This matters more than most buyers realise. There are two fundamentally different types of generator, and choosing the wrong one can damage your equipment. Conventional (AVR) generators produce power directly from the alternator. The voltage and frequency fluctuate slightly with engine speed and load. They’re fine for power tools, heaters, and anything with a simple motor. They’re NOT safe for sensitive electronics — laptops, TVs, smart home systems, or medical equipment. Inverter generators convert the raw AC power to DC, then back to a clean AC sine wave using electronics. The result is power as clean as (or cleaner than) mains electricity. Total Harmonic Distortion (THD) is typically under 3%, compared to 10–25% for conventional generators. They’re also quieter because the engine speed varies with load instead of running at a fixed 3,000 RPM. For home backup, an inverter generator is almost always the right choice. Your fridge, boiler controls, TV, router, and anything with a circuit board needs clean power. The only exception is if you’re exclusively powering resistive loads (heaters, incandescent lights) or industrial motors — then a conventional generator is cheaper and works fine. MobCater’s inverter range includes the GP2000i, GP3500i, GP3800iE, GP5000i, GP8000iE, and Champion Atom Fusion. The open-frame dual fuel models (GP5500E-DF, GP6500E-DF) are conventional generators suited to workshops, building sites, and powering heavy equipment.

Frequently Asked Questions

Can I run my whole house on an LPG generator?

It depends on what you mean by “whole house.” If you want to keep the essentials running — fridge, heating controls, lighting, TV, and charging — a 3,000–3,500W generator handles that easily. If you want to run an electric shower (8,000–10,000W), electric cooker (7,000W+), or multiple high-draw appliances simultaneously, you’d need an 8,000W+ model and a transfer switch installed by an electrician. Most people find that backing up the essentials with a mid-range generator is far more cost-effective than trying to replicate their full mains supply.

How long will a propane cylinder last on a generator?

A standard 47kg propane cylinder will run a 3,500W generator at 75% load for approximately 40–43 hours. At half load, you’ll get closer to 55–60 hours. A smaller 19kg cylinder gives roughly 16–18 hours at 75% load on the same generator. Consumption varies significantly by generator size and load — the table in the running costs section above gives specific figures for each model.

Are LPG generators safe to use at home?

Yes, provided you follow basic safety rules. The generator must run outdoors (never in a garage, shed, or conservatory), at least 3 metres from any opening into your home. The LPG cylinder must stand upright on a firm surface. Use proper LPG-rated hoses and fittings, and check connections with leak detection spray. The biggest risk with any generator is carbon monoxide poisoning from exhaust fumes — keep it outside and you eliminate that risk entirely.

Do I need a transfer switch for a home generator?

Legally, you must not connect a generator directly to your home’s mains wiring without a transfer switch (also called a changeover switch). Back-feeding electricity into the grid is illegal and potentially lethal — it energises power lines that utility workers believe are dead. For occasional use, running extension leads from the generator to individual appliances is the simplest approach. For a permanent setup, pay an electrician £300–500 to install a manual transfer switch. Automatic transfer switches (which start the generator and switch over automatically during a power cut) cost £800–1,500 installed.

Is an inverter generator worth the extra cost for home backup?

Almost certainly yes. If you’re powering anything with electronics — fridge, boiler, TV, laptop, router — you need the clean sine wave output that only an inverter generator provides. A conventional generator’s “dirty” power can damage circuit boards, corrupt data, and shorten appliance life. Inverter generators are also significantly quieter, which matters when you’re running one next to your house at 2am during a power cut. The price premium is typically 20–40% over a conventional generator of the same wattage, but you avoid the risk of damaging hundreds of pounds worth of household electronics.

What’s the difference between dual fuel and dedicated LPG generators?

Dual fuel generators can run on either petrol or LPG, switched by a valve or control panel. Most generators MobCater sells are dual fuel. The advantage is flexibility — you can use whichever fuel is available. Dedicated LPG generators (like the Greengear range) run only on propane, which means simpler fuel systems and optimised combustion for LPG. If you have a permanent propane supply and no need for petrol, a dedicated LPG model is slightly more efficient. If you want flexibility, dual fuel is the way to go.

Can I use a generator to charge a battery storage system instead of powering appliances directly?

Yes, and it’s increasingly popular. Instead of running a generator whenever you need power, you run it for a few hours to charge a battery bank (like the EcoFlow DELTA series or a lithium leisure battery setup), then use the stored energy throughout the day. This approach means the generator runs at optimal load (75–80%) for a shorter period rather than ticking over at low load all day — which is better for the engine and more fuel-efficient. For narrowboats and off-grid homes, a combination of solar panels, battery storage, and an LPG generator as backup is the most practical and economical setup.