How To Calculate The Per Unit Running Cost Of A Generator

How To Calculate The Per Unit Running Cost Of A Generator_Generator Pro

In the UK we’re very fortunate to have a consistent supply of electricity from the National Grid. However, for those times when you might need a back-up – during a power cut for example – a generator is a great option. They are also useful if you need power where there isn’t access to mains power.

Is Running A Generator Expensive?


The cost of installing a generator can vary from anything to £650-£15,000 and sometimes more. It all depends on your power requirements. There are many types of generator available for domestic and commercial use, from Hyundai diesel generators and Kohler petrol generators to name a few.


To decide on the best type of generator for you, consider what you need it for. Will you be using it as back-up power for your home, using it at your business, or only on occasion. Such as a party or other event.

The wattage of a generator is part of what will affect the running cost. The larger the power output of your generator, the larger the cost.

To work out how much wattage you need, make a note of what you would need to run with the generators, such as lighting and heating. If you will be running any appliances you can usually find information on watts on the appliance itself. If not, a search online should help you find it. For example, a TV uses up to 400 watts an hour.

The website, Popular Mechanics, has a chart of rough estimates of energy loads of typical home appliances which you may find useful.

Once you have decided what you want to power with a generator and the wattage, it’s sensible to add approximately 20-30% extra to ensure that you have excess capacity. This will give you the total amount of watts (W) required. If you divide this by 1,000 you get the amount of kilowatts (kW) (e.g. 8,000 W is 8 kW).

Operating Costs

When deciding between generators it’s important to factor in fuel consumption.

Diesel powered generators tend to be large and therefore suitable for business use or large homes. The initial cost to buy is more expensive but long-term running costs are fairly low.

Using a petrol generator is cheaper than diesel and more suitable for a home environment. Fuel economy isn’t as efficient though and they can be quite noisy.

You can find a guide to the pros and cons of each fuel here. Depending on the fuel used and size of the home it can cost around £40-100 a day to run a generator.If you’re unsure which type of generator is right for your needs, we’re happy to help. Contact us today.

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