Over its life a generator costs far more in diesel than it did to buy. These are the consumption figures for the sets in our catalog, at 75% load, followed by what pushes the number up or down on a real site.
How to read the figures
Each figure below is litres per hour at 75% load — a realistic working point for a correctly sized set. Multiply by your daily running hours and the price of diesel, and you have the running cost that matters far more than the purchase price.
| Generator | Output | Litres per hour | Fuel tank |
|---|---|---|---|
| Perkins 20 kVA | 20 kVA / 16 kW | 4 L/h | 60 L |
| Perkins 30 kVA | 30 kVA / 24 kW | 5.8 L/h | 80 L |
| Cummins 40 kVA | 40 kVA / 32 kW | 7.6 L/h | 110 L |
| Perkins 60 kVA | 60 kVA / 50 kW | 11 L/h | 150 L |
| Cummins 60 kVA | 60 kVA / 50 kW | 10 L/h | 150 L |
| Deutz 80 kVA | 80 kVA / 64 kW | 14.5 L/h | 180 L |
| Cummins 100 kVA | 100 kVA / 80 kW | 18 L/h | 230 L |
| Perkins 150 kVA | 150 kVA / 120 kW | 27 L/h | 300 L |
| Deutz 200 kVA | 200 kVA / 160 kW | 36 L/h | 400 L |
| Cummins 250 kVA | 250 kVA / 200 kW | 45 L/h | 450 L |
| Deutz 350 kVA | 350 kVA / 280 kW | 63 L/h | 600 L |
| Cummins 350 kVA | 350 kVA / 280 kW | 54 L/h | 570 L |
| Cummins 500 kVA | 500 kVA / 400 kW | 90 L/h | 900 L |
| Perkins 650 kVA | 650 kVA / 520 kW | 118 L/h | 1100 L |
| Cummins 1000 kVA | 1000 kVA / 800 kW | 180 L/h | 1600 L |
What changes fuel consumption
- Load — a set burns more as it works harder, but uses fuel most efficiently when it is properly loaded
- Sizing — an oversized set running lightly burns more fuel per unit of power delivered
- Engine brand — at part load, Perkins has the lowest consumption of the three we carry
- Maintenance — clogged air and fuel filters make any engine thirstier
- Ambient heat — a set that is not specified for the climate works harder to make the same output
How to keep the fuel bill down
Buy the right size. That is most of it — a set matched to the measured load, rather than one bought large to be safe.
Then keep it serviced on running hours, typically every 250 hours for oil and filters, so it stays as efficient as the day it was commissioned.
More buying guides.
Quick answers.
Not covered here? Send us your appliance list or a photo of your distribution board and we will size it for you at no cost.
Ask an engineerThe consumption for each rating we stock, including the 100 kVA set, is listed in the table on this page at 75% load. The exact figure on your site depends on how heavily the set is loaded.
Yes. A larger engine has more of itself to keep turning, so an oversized set burns more fuel for the same output — one more reason not to oversize.
Divide the tank size by the litres per hour. Both figures are on each product page, so you can work out the running time for any set in the catalog.
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