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Why are diesel generators better than petrol?

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One of the biggest choices you’ll have when choosing the right generator is the choice between petrol and diesel generators.

There are several pros and cons to both types of generators that we get into further down in this article, but one of the biggest advantages of diesel engines is they are more energy efficient than petrol engines.

Although petrol is a lower cost than diesel in the UK, a diesel generator’s power production uses less fuel to produce the same power output as its petrol counterparts, making diesel engines more cost-effective to run than petrol engines in the long term.

They are also more powerful than other generators, such as inverter generators. Their diesel engine will be able to produce greater energy supplies making them more popular in commercial industries, construction, and large events.

The disadvantages such as noise levels and the fact they tend to smell more with the fumes they produce can be unwelcome features, especially for use closer to homes and populated areas.

As with any decision, it’s worth weighing up the pros and cons before purchasing so you can make an informed decision.

Read on as we look further into why a diesel generator may be better than petrol, and which one would best suit your needs.

Throughout this article, we look at why diesel-powered generators may be a better choice over petrol engine generators.

We’ll look at the pros and cons of diesel and petrol generators and cover the major advantage of diesel generators vs petrol generators.

Diesel generators vs petrol generators

The type of generator you need depends greatly on what you need the generator to supply power production for.

If your generator will have higher power demands, such as for use on construction sites, industrial companies, large events, or powering farming equipment, you’ll need a generator suitable for heavy commercial use that’s capable of running for long periods with a heavy load.

If you need a generator for low-load applications such as domestic appliances, recreational vehicles, and smaller loads, you’ll want a generator suited for infrequent or temporary use.

At a glance: diesel generators

Diesel generators are better for larger power needs with high demand for generator use.

For example, an outdoor project site may have very high demands for a generator to run equipment and power vehicles and tools, in this instance, a portable diesel generator is most likely to be the preferred choice.

On average, diesel generators burn at a rate 50% less than petrol-powered engines. Making a diesel engine more fuel efficient over time.


  • Less maintenance is needed – Diesel engines have fewer components and a simpler fuel delivery system so although they still need regular generator maintenance, there is less they need maintenance on.
  • Fuel efficient – they have a longer running time and are more cost-effective to run than petrol generators.
  • Longer life span – compared to a petrol generator, on average the lifespan of a diesel generator is three times as long.
  • Greater power output – Diesel generators can produce more power and handle larger loads than petrol generators, making them the more obvious choice for most industrial companies.
  • Safer to store – Although it’s still flammable because diesel fuel is less flammable than petrol, it makes storing and running diesel generators safer.


  • The cost of diesel – Diesel fuel is more expensive than petrol in the UK.
  • Noise – Diesel generators are noisier when running than petrol generators.
  • Harmful carbon dioxide fumes – Diesel generators produce more harmful fumes. They need to be run in well-ventilated areas.
  • They tend to be bigger and heavier – Although you can get portable diesel generators, they are bulky due to the size of their fuel tanks.

Fuel efficiency

A diesel motor’s higher compression means it’s generally burning fuel slower than a petrol engine.

During its optimum operating range, you can expect a diesel generator to run at about 40% efficiency and up to 80% during total load capacity.

At a glance: petrol generators

A petrol generator has various pros and determining factors that lead people to choose petrol over generators with diesel engines, let’s look at the pros and petrol generator cons.


  • Petrol is cheaper – The cost of petrol is cheaper than diesel in the UK so filling the tank on a petrol generator will cost less.
  • They are quieter – On the whole, a petrol generator will run quieter than a diesel generator, making them more preferred for home use, and portable petrol generator better for activities such as camping.
  • Less expensive to buy – Price ranges for a petrol generator tend to be less than a diesel generator.
  • Less noise pollution – Petrol generators produce less harmful carbon dioxide fumes compared to diesel generators, although you still need to be mindful of running them in well-ventilated areas.


  • Require more frequent maintenance – because petrol generators use a spark ignition system they require more maintenance, for example, to change spark plugs.
  • Shorter lifespan – Petrol generators don’t tend to last as long as diesel generators, although regular maintenance will help improve their lifespan.
  • Flammable risks – Because petrol is more flammable, you need to make sure you take measures such as draining all petrol from the tank before you put the generator into storage.
  • Not as fuel efficient – A petrol generator’s fuel efficiency is lower than a diesel generator, meaning you’ll burn more fuel.

Fuel efficiency

Petrol engines are not as efficient as a diesel engine. Generally, petrol generators burn approximately 50% more energy over extended periods than diesel generators.

Why is a diesel generator better?

A diesel generator is better because a diesel engine gets much better fuel economy. Diesel engines do not have to burn as much energy to produce the same about of electricity.

If you are thinking of choosing petrol, there are a few benefits that outweigh the efficiency of diesel, but a lot of the decision comes down to your needs.


Can a diesel generator power a house?

To put it simply, yes. Diesel generators can handle large loads such as heavy machinery and powering portable construction equipment, so in terms of generating power for a whole house, a diesel generator should be more than capable.

When choosing your generator look at things such as the load the generator can manage and think about what you’ll be powering in your home, lights, appliances, etc.

Why do diesel generators not have inverters?

Diesel generators are designed to produce high levels of power, they have larger fuel tanks for greater power production.

Inverter generators are designed to generate energy using lower amounts of fuel, which makes them more energy efficient but less powerful, they are better for reduced power and are not suitable for diesel generators.


Although they are noisier to run, we tend to defend diesel generators because of their efficiency and ability to generate large amounts of power.

If you’re looking to supply power for large commercial use or even to power a house, a diesel generator is going to be cheaper to run in the long term.

If you are looking to power smaller loads and appliances on occasions such as camping, a portable petrol generator will do the trick.

If you’d like to discuss which generator is best for you, contact Solent Power, our team will be happy to help.

We are also one of the leading suppliers of generators, so be sure to check out our range of generators in our online shop.

Paul Phelps Solar Power Owner
Paul Phelps
Paul is the MD of Solent Power and specialises in emergency power solutions, helping to protect your facilities from power loss. Get in touch with us today to discuss the different power brands that we can offer and how they can suit your needs.
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