Site power is one of those things you do not think about until the day there is none. First fix on a new build, a barn conversion with the supply not yet energised, a shopfit at 6am before the landlord turns anything on – and suddenly the difference between a productive day and a wasted one is whether somebody remembered to put a generator in the van.
The trouble is that the word “generator” covers two completely different machines. There is the quiet suitcase inverter that runs a laptop, a couple of lights and a chop saw without upsetting the neighbours. And there is the yellow-framed 110V site machine that lives on a main contractor job and will happily run a 110V breaker all day. Buy the wrong one for your work and you will either be stood next to something far too loud for a domestic street, or you will be nursing a transformer and an extension reel trying to get a 110V grinder going off a 230V socket.
This guide is for UK trades buying a site generator in 2026. All prices are approximate UK street prices including VAT and move about with retailer, fuel prices and promotion, so treat them as a guide rather than a quote.
Our quick verdict
For most UK trades who work on managed sites, the Stephill SE34003S at around GBP 720 is the machine to beat. It is 3.4kVA, it runs a Honda GX200 engine, and critically it gives you 110V 16A and 32A outlets straight off the panel with no transformer in the van. That last point is the whole argument. If your tools are 110V, buy a 110V generator.
If you work domestic, refurb and shopfit, and the kit you need to run is 230V – lights, laptops, a track saw, a vacuum – the Honda EU22i at around GBP 1,095 is still the one that earns the money back. It is 21kg, it is quiet enough to run on a residential street at 7am without a conversation, and it produces genuinely clean power. It is expensive and it is worth it.
If GBP 1,095 is not happening, the Hyundai HY3200SEi at around GBP 764 gives you more output (3.2kW peak) for less money, with a 3-year UK warranty and parts you can actually get. It is heavier and it is not a Honda, but for a machine that gets used a dozen times a year it is the sensible buy.
How to choose a site generator
110V or 230V – decide this first
This is the single decision that matters and everything else is detail. If you are on main contractor sites, your tools are 110V because CDM-era site rules and most principal contractors demand it. A 230V-only generator on that job is useless to you unless you carry a step-down transformer, and running a transformer off a small generator eats capacity you have already paid for.
A proper site generator gives you 110V 16A and 32A yellow sockets on the panel, usually alongside a 230V socket for the kettle and the chargers. That is what the Stephill machines and the trade-focused Hyundai and Evolution units do. Domestic and shopfit trades who never see a 110V tool can ignore all of this and buy a 230V inverter, which will be lighter, quieter and cheaper to run.
Sizing – kVA, kW and the starting surge
Generators are sold in kVA and rated in kW, and the two are not the same. A 3.4kVA machine typically gives you about 2.7kW of continuous real-world output. Work out what you actually need to run at once, not the total of everything in the van.
The catch is inrush. Anything with an induction motor – a cement mixer, a bench saw, a compressor, an older SDS drill – draws several times its running current for the first second or two. A 1.5kW mixer can pull 4kW or more on start-up. Size for the surge, not the label. A rough rule that has served plenty of trades well: take your biggest motor tool, double it, then add everything else you want running at the same time.
Inverter or conventional AVR
Inverter generators produce a clean sine wave and vary engine speed to match load. That means quieter running, better fuel economy at part load, and power that will not upset a laptop, a battery charger or the electronics inside a modern brushless tool. Conventional AVR generators run at a fixed 3,000rpm regardless of load – noisier, thirstier, but usually cheaper per kW and generally more rugged in a knockabout site frame.
If you are charging batteries, running lighting or plugging in anything with a circuit board, get an inverter. If you are running a mixer and a breaker on a groundworks job, a conventional site machine is fine and will cost you less.
Noise, and the neighbours
Noise is a practical constraint, not a nicety. A Honda EU22i in Eco mode sits around the high 40s dBA at seven metres; a Hyundai inverter is quoted around 54-59 dBA at seven metres; an open-frame site generator is comfortably into the 70s. On a domestic job at 7:30am, an open-frame machine will get you a phone call. On a site with hoarding up, nobody cares.
Running costs and fuel
Fuel is the cost people forget. A small inverter at part load will do four to eight hours on a tank and cost you very little; a 6kVA open-frame machine at full chat will drink a jerry can in a day. Eco or smart throttle modes are worth having for that reason alone.
Also plan for the machine sitting idle. Petrol left in a carburettor over winter is the most common reason a generator will not start in spring. Either drain it, use a fuel stabiliser, or run it dry before it goes in the container.
Electric start, wheels and the boring stuff
Recoil start is fine on a 21kg inverter and a genuine irritation on a 40kg-plus machine on a cold morning. Electric start with a key fob costs a little more and you will be glad of it in January. Likewise wheels and a proper frame handle: a 35kg generator with no wheel kit is a two-man lift into a van every single day, and that adds up.
The best site generators at a glance
Approximate UK street prices including VAT for 2026. Prices vary by retailer and promotion.
| Generator | Output | 110V outlets | Best for | Approx. price |
| Stephill SE34003S | 3.4kVA / 2.7kW | Yes – 16A + 32A | Best overall / main contractor sites | GBP 700-760 |
| Honda EU22i | 2.2kVA / 1.8kW | No – 230V only | Quietest / domestic and shopfit | GBP 1,050-1,095 |
| Hyundai HY3200SEi | 3.2kW peak / 2.8kW cont. | No – 230V only | Best value inverter | GBP 740-790 |
| Honda EU32i | 3.2kVA / 2.6kW | No – 230V only | Big quiet 230V output | GBP 1,970-2,045 |
| Honda EU10i | 1.0kVA / 0.9kW | No – 230V only | Lightest / lights and chargers | GBP 769-795 |
| Stephill SE3400+ | 3.4kVA / 2.7kW | Yes – 16A + 32A | Economy site machine | GBP 650-720 |
The picks in detail
Best overall – Stephill SE34003S
At around GBP 720 the SE34003S is the machine most UK trades on managed sites should be buying. It is 3.4kVA / 2.7kW, built around a Honda GX200 6.5hp four-stroke engine, and it puts 110V 16A and 32A sockets on the panel alongside a 230V outlet. That combination means you turn up, plug in, and work – no transformer, no borrowed extension off somebody else’s board.
Stephill build in the UK and the frames are made for being thrown in and out of a van, which is not something you can say about every import at this money. The GX200 is about as proven as small petrol engines get, parts are everywhere and any small-engine shop will look at it. The trade-off is that this is a conventional AVR machine, not an inverter: it runs at fixed revs, it is loud, and it will drink more fuel at low load than an inverter of the same size.
It is a site machine and it behaves like one. Do not buy it for a quiet residential job.
Quietest and cleanest – Honda EU22i
The EU22i at around GBP 1,095 is the generator everyone else gets compared to, and after years on the market it has still not really been beaten on the things that matter to a working tradesman: noise, weight and reliability. It is 2,200W peak, 21kg, and the Eco Throttle system drops the revs to match the load so it is barely audible on a light load.
The inverter output is clean enough for laptops, test equipment and battery chargers without a second thought, which matters more than people expect – sparks running test kit and anyone charging a stack of 5Ah packs on a job should be paying attention here. Fuel economy at part load is excellent, and resale is famously strong, which quietly closes some of the gap on the purchase price.
The honest limitations: 1.8kW continuous is not a lot, it is 230V only, and it costs more than double a comparable Hyundai. If you need to run a 110V breaker, this is the wrong machine no matter how good it is.
Best value – Hyundai HY3200SEi
At around GBP 764 the HY3200SEi gives you 3,200W peak and 2,800W continuous from a 210cc four-stroke, in a closed-case inverter design with electric start, a remote key fob and a built-in wheel kit. Two 230V 13A sockets and a 12V DC outlet. Quoted at 54-59 dBA at seven metres, so noticeably louder than the Honda but not in open-frame territory.
The real argument for Hyundai is the support: a 3-year UK warranty, UK parts and service backup, and next-day availability on consumables. That is a materially different proposition from a no-name import at the same price. It is 35kg, so the wheel kit is not optional in practice.
It is not a Honda. Long-term durability under daily commercial use is not in the same league, and the engine is not going to see fifteen years. But for a machine that comes out of the container a couple of dozen times a year, you can buy three of these for the price of one EU22i, and that maths is hard to argue with.
Biggest quiet output – Honda EU32i
If you need real 230V output without the noise of an open frame, the EU32i at around GBP 2,045 is the answer. 3.2kVA of clean inverter power, still genuinely quiet, and it will run a small compressor or a decent site light rig alongside your tools. It is expensive enough that it only makes sense if you are using it weekly – hire is cheaper for occasional work at this level.
Lightest – Honda EU10i
At around GBP 795 and 13kg, the EU10i is the one-hand-carry option. 1kVA is not going to run a chop saw, but it will run lighting, chargers, a laptop and small hand tools all day on very little fuel. Surveyors, inspection work and anyone who needs power rather than grunt should look at it before spending more.
Economy site machine – Stephill SE3400+
The SE3400+ is the Super Economy version of the same 3.4kVA platform, usually a little cheaper at around GBP 680 and aimed squarely at fuel cost per day. Same 110V outlet arrangement, same site-frame approach. If you are running a generator most days rather than occasionally, the fuel saving is the part of the spec sheet worth reading.
Getting the most out of a site generator
Run it outside, always, and never in a van with the doors shut or in a part-enclosed space. Carbon monoxide from a petrol generator kills people every year and it does it quickly and without warning. If the machine is running, it is outside and there is airflow around it.
Keep it level and keep it dry. Most small generators will not run reliably on a slope, and a soaked panel is an electrical problem you do not want. A cheap generator cover and a scaffold board are five minutes of setup that save a call-out.
Do not run it at 100 percent load all day. Sizing so the machine sits around 50-75 percent means better fuel economy, less heat, less noise and a longer engine life. If you are constantly maxing it out, you bought too small a machine.
Service it like a tool, not a spare. Oil change at the intervals in the book, air filter kept clean, fresh fuel. And run it under load for twenty minutes every month or two if it is otherwise sat in the container – generators that die are almost always generators nobody started.
Finally, chain it. A generator is a two-man lift with a strong second-hand market and it walks off sites constantly. Chain it to something that does not move, and if it lives in the van, it goes in the site box or gets bolted down.
Frequently asked questions
Do I need a 110V generator for site work?
If you work on main contractor sites, almost certainly yes – most principal contractors mandate 110V tools, and a 230V-only generator will not power them without a step-down transformer. If you work domestic, refurb or shopfit, 230V is fine and you will get a lighter, quieter, cheaper machine for it.
What size generator do I need for power tools?
For lights, chargers, a laptop and small hand tools, 1-2kVA is plenty. For a track saw, chop saw or vacuum, 2.5-3.4kVA is the sensible band. If you are running a mixer, a breaker or a compressor, go 5kVA-plus and size for the starting surge – motors can draw several times their running current at start-up.
Are cheap generators worth buying?
For occasional use, a budget machine from a brand with UK parts and warranty support will do the job. What you lose is engine longevity, noise performance and clean power – which matters if you are charging batteries or running electronics. What to avoid is the unbranded end of the market where nobody stocks a carburettor and the warranty is a web form.
Can I run a generator inside a van?
No. Petrol generators produce carbon monoxide and running one in an enclosed or part-enclosed space is genuinely dangerous. Run it outside, on level ground, with clear air around the machine, and keep it away from open windows and doorways.
Should I buy or hire a site generator?
If you need one more than about a dozen days a year, buying wins – hire on a 3kVA machine will typically cover the purchase price inside a couple of months of regular use. For a one-off pour or a single week without supply, hire is cheaper and somebody else deals with the servicing.
Is an inverter generator worth the extra?
For anything with electronics in it, yes. Clean sine-wave output protects chargers, test kit and laptops, and the variable engine speed means less fuel and far less noise at part load. For a mixer and a breaker on an open site, a conventional AVR machine is fine and cheaper per kW.
