Generators
Generator Fuel Consumption Chart: How Much Diesel Does a Generator Use per Hour?
Short answer
A diesel generator typically uses about 0.25 to 0.3 litres per kWh produced. A 20 kVA unit (about 16 kW) at 75% load produces around 12 kW and burns roughly 3.2 to 3.6 litres an hour. Always check the manufacturer's datasheet, because engine and load affect consumption.
Approximate consumption
| Generator | Real power (at 0.8 power factor) | At 50% load | At 75% load | At 100% load |
|---|---|---|---|---|
| 10 kVA | 8 kW | ~1.5 L/h | ~2.0 L/h | ~2.6 L/h |
| 20 kVA | 16 kW | ~2.7 L/h | ~3.6 L/h | ~4.8 L/h |
| 30 kVA | 24 kW | ~4.0 L/h | ~5.4 L/h | ~7.2 L/h |
| 50 kVA | 40 kW | ~6.5 L/h | ~9 L/h | ~12 L/h |
| 100 kVA | 80 kW | ~12 L/h | ~17 L/h | ~23 L/h |
Rounded estimates from about 0.3 L per kWh. Real figures vary by engine; use the datasheet.
Estimate your running cost
Cost per hour = litres per hour × diesel price. For example, 3.6 L/h at an assumed KES 200 per litre costs about KES 720 per hour, which is roughly KES 45 per kWh for a 16 kW load at 75%. Add servicing costs. Use today's pump price.
Reduce fuel use
- Right-size the generator; very lightly loaded engines waste fuel.
- Keep filters and oil in good condition.
- Run solar plus battery for daytime loads and use the generator only when needed.
Related
See generator sizing and solar vs generator costs.
Common questions
Does a bigger generator use more fuel?
At the same load, a larger engine often wastes more fuel than a properly sized one.
How long does a full tank last?
Divide the tank volume by the litres per hour at your load.
Does load affect efficiency?
Yes. Generators are usually most efficient at around 60 to 80% of rated load.