Whether you are buying your first or next diesel power generator, you will likely be asked what size you need. For those that are unaware, the size of a diesel generator is measured in kVA, which isn’t a measurement typically known outside of the generator industry, as most power applications are measured in kilowatts(kW). 

For that reason, when people are searching for diesel generators, they will come across as two very similar terms, such as 20kW and 20kVA generator, but what is the difference between the two? 

What is kW?

The abbreviation for kilowatts, kW is the actual amount of power that is converted into useful power which can be used by a diesel generator. Due to that reason, kW often has two additional names, being ‘actual power’ or ‘working power’, as it’s the amount of power supply required to make appliances function. 

To keep it simple before we explain kVA, kW is the most important part to look at – going back to the example above, it might be much easier to simply look at the 20kW generator for sale over the 20kVA alternative. 

What is kVA?

That being said, kVA is still useful for those that have a better understanding of the diesel generator set they are looking to purchase. Most commonly known as ‘apparent power’, the kVA tells you how much total amount of power is being used by in the system overall. 

Another way to think of it, if the efficiency of an appliance is 100%, then the kW will be equal to the kVA – though this is rarely the case as no appliance is ever fully efficient, meaning not all apparent power will be converted into useful output. 

The power factor

Before we look at converting the two different power measurements, you will need to know the efficiency of the electrical system. This is typically measured as a power factor, between 0 and 1 – with the closer to the power factor of 1, the more efficiently the kVA is being converted into useful kW. For reference, all standard diesel generators have a power factor of 0.8, making diesel generators highly efficient. 

How to convert kW to kVA

Now that we have the power factor, it is much easier to convert the kW to vKVA and vice versa. 

  • To convert kW to kVA

Actual power (kW) / power factor (pf) = apparent power (kVA)

  • To convert kVA to kW

Apparent power (kVA) x power factor (pf) = actual power (kW)

What to look for when you are purchasing a diesel generator 

If you are just beginning your search for a diesel generator for sale, it’s important to consider the differences in these power rates, especially when looking at your power requirements. It’s also worth noting that the USA predominantly uses kW when referring to power generators, whereas the UK and many European countries prefer kWA.

For those that are searching for one of the best diesel power generators, fear not, Generators OnLine is here to help. Our specialist team will be more than happy to recommend the most suitable generator for your specific power demands, enabling you to have suitable backup power in the chance of a power failure. Our generator range starts from as low as 1kW, but for reference, the 20kVA generator is one of our most popular products available.