Yes, you can use red diesel in most diesel generators - but only under certain conditions. Red diesel is legally permitted for off-road and non-road uses, which includes many backup generators, construction site power, and agricultural applications. However, it cannot be used for generators that power equipment or vehicles used on public roads.

Keep in mind that red diesel is taxed differently than standard white diesel, and its use is closely regulated in the UK. It's important to check your specific use case to ensure you are not using it incorrectly.

Whether a diesel generator is cheaper than grid electricity comes down to how often you use it, current fuel prices, and the efficiency of your generator.

In remote or off-grid locations, running a diesel generator can be more cost-effective, especially where connecting to the mains is expensive or not possible. Diesel generators are also ideal for temporary power needs, emergency backup, events, or powering tools on construction sites.

However, for regular, long-term power supply - especially in areas with reliable and affordable grid electricity - using a diesel generator will usually cost more over time. That’s because of ongoing fuel costs, maintenance, and potential downtime.

To decide what’s more economical for you, consider:

• Your average power consumption (kWh)
• Current diesel prices vs local electricity rates
• How many hours per day/week the generator will run
• Maintenance and servicing costs

No, it's not safe to refuel a diesel generator while it’s running. Although diesel fuel is less flammable than petrol, refueling a hot or running generator still poses serious fire and safety risks.

When a generator is in use, it generates high heat, and spilled fuel or vapours can ignite if they come into contact with a hot engine or exhaust components. There’s also a risk of static discharge or splash-back, which could cause burns or other injuries.

For safe refuelling:

• Always switch off the generator
• Allow it to cool down fully
• Refuel in a well-ventilated area, away from ignition sources
• Follow the manufacturer’s safety instructions

The amount of diesel a generator uses per hour depends on its size, load, and efficiency. On average:

• A 5kW diesel generator will use around 1–1.5 litres of fuel per hour at 50–75% load
• A 20kW generator may use 3–4 litres per hour
• Larger commercial units can consume 10+ litres per hour, depending on usage

Fuel consumption increases with higher loads, so running a generator at or near full capacity will burn more diesel per hour.

Tip: For better fuel efficiency, choose a generator that matches your power needs closely - running a generator too large for your usage wastes fuel.

Need help estimating your running costs? Contact our team for a personalised usage breakdown based on your setup.

Choosing the right size diesel generator depends on the total wattage of the appliances or equipment you want to power.

Here’s a quick guide:

• For home backup power (lights, fridge, boiler, Wi-Fi, sockets): a 5kW to 8kW generator is typically sufficient. But you may need a larger one depending on what you need to run
• For small businesses or offices (computers, lighting, security systems): look at 10kW to 20kW models
• For industrial or site use (machinery, welders, compressors): you may need a 30kW+ three-phase generator

To avoid under-sizing or over-spending, calculate your peak load requirements or speak to our generator experts for tailored advice.

Tip: Always allow a 20–30% buffer above your expected load for safe and efficient operation.

The main difference lies in engine speed, durability, and intended use:

1500rpm generators:

• Run at a slower engine speed,
• Designed for longer,
• continuous use,
• Quieter and more fuel-efficient ideal for backup power, 
• Commercial, or off-grid setups

3000rpm generators:

• Run at a higher speed
• Typically lighter
• More compact and lower cost
• Best for occasional or short-term use
• Common in portable or mobile applications

Tip: If you need a generator for regular use or extended runtimes, go for a 1500rpm model. For occasional backup or DIY jobs, a 3000rpm unit may be more budget-friendly.

Still unsure? Browse our collection of 1500rpm and 3000rpm generators, or speak to our support team for expert help.