Generators
Diesel vs Petrol Generator: Which Should You Buy?
Short answer
Petrol generators are cheaper and lighter and suit small, occasional loads. Diesel generators cost more upfront but are more fuel-efficient, more durable for long running and available in much larger sizes, so they suit businesses, standby power and anything running for many hours.
Comparison
| Petrol | Diesel | |
|---|---|---|
| Purchase price | Lower | Higher |
| Fuel efficiency | Lower | Higher |
| Typical size | Small, up to a few kVA | Small to very large |
| Durability for long running | Moderate | Better |
| Noise | Often noisy (portable) | Quieter with a canopy |
| Fuel storage | Evaporates, more flammable | Safer and keeps longer |
Which should you choose?
- Petrol: a few hours of use occasionally, small loads, portability.
- Diesel: frequent or long outages, businesses, higher loads, automatic standby.
Other considerations
- Sizing: see what size generator you need.
- Automatic changeover for standby use.
- Canopy, exhaust and ventilation for safe installation.
- Running cost compared with solar. See solar vs generator.
Common questions
Which uses less fuel?
Diesel generators generally use less fuel for the same output.
Can I run a generator indoors?
Never. Exhaust contains carbon monoxide. Install outdoors or in a ventilated generator room.
How long can a generator run continuously?
Standby units are designed for hours of use; check the manufacturer rating for continuous operation.