Diesel Stromerzeuger: Der ultimative Kaufratgeber 2026

Diesel Generators: The Ultimate Buying Guide 2026

Alexander Harlinghausen

Table of contents
Key facts at a glance What is a diesel generator? How it works and how it is built, simply explained Diesel vs. petrol generator: an honest comparison How much power do I need?

Last updated: January 2026 | Reading time: 22 minutes

Looking for a reliable diesel generator but not sure which model suits your requirements? This buying guide covers everything you need to know before you buy – from choosing the right size and the technical differences to specific product recommendations for different applications.

Key facts at a glance

In a hurry? A diesel generator is the first choice if you:


  • - Need to generate power regularly or over long periods
  • - Need high output (5 kW and above)
  • - Value low running costs
  • - Are looking for a robust, long-lasting generator

Our top recommendations for 2026:

Application
Model
Power
Ideal for
Private/camping
FME XG-SF 5600D
5.5 kW
Motorhome, summer house, emergency preparedness
Detached house
FME 8000iD
8 kW
Home backup power, sensitive electronics
Business/trades
FME SP7000D
7 kW
Building sites, mobile use
Industry
FME SimpleGen B20
20 kVA
Continuous operation, standby power systems

Before we go into detail, here is a compact overview of recommended diesel generators for different requirements:


Model
Type
Power
Key features
Price
Who is it for?
FME XG-SF 5600D Carbon
Diesel inverter
5.0 kW / 5.5 kW max
Heating oil compatible, ECO mode, electric start
1.889,95 €
Camping, leisure, light backup power
FME 8000iD
Diesel inverter
8 kW
230V & 400V Same Power, ATS input, CO shutdown
2.999,95 €
Detached houses, sensitive devices
FME SP7000D
Diesel AVR
7 kW
Same Power technology, runs on diesel/heating oil
1.799,95 €
Building sites, trades, heavy-duty applications
FME SimpleGen B20
Industrial generator
20 kVA (16 kW)
Baudouin engine, 4-stage protection, water-cooled
6.569,95 €
Business, continuous operation, standby power systems

All prices incl. VAT, as of January 2026

What is a diesel generator? How it works and how it is built, simply explained

A diesel generator – often also called a diesel generator set or diesel backup generator – converts the chemical energy in diesel fuel into electrical energy. At its heart is a diesel engine that drives an alternator.


How a diesel generator works in detail


  1. 1. Fuel supply: Diesel is pumped from the tank to the injection pump
  2. 2. Combustion: The diesel engine compresses air so much that it heats up. Injected fuel droplets ignite on their own (compression ignition)
  3. 3. Mechanical energy: Combustion drives the pistons, which turn a crankshaft
  4. 4. Power generation: The crankshaft drives the alternator, which generates electricity by electromagnetic induction
  5. 5. Voltage regulation: An AVR (automatic voltage regulator) or, on inverter models, electronic control ensures a constant output voltage

The main components of a diesel generator


  • Diesel engine: Usually air-cooled (small models) or water-cooled (industrial generators)
  • Alternator: Generates the electrical power
  • Voltage regulator: AVR or inverter technology for a stable voltage
  • Fuel system: Tank, pump, filter, injectors
  • Cooling system: Air or water cooling
  • Soundproof enclosure: Reduces operating noise (optional)
  • Control unit: Control panel, fuses, protective circuits

Good to know: Modern diesel generators have several protective mechanisms – overload protection, low-oil shutdown, overheating protection and, on inverter models, often an automatic CO shutdown for safe operation.

Diesel vs. petrol generator: an honest comparison

The most common question when buying a generator: should I go for diesel or petrol? The answer depends on exactly what you need it for. Here is the full comparison:


Fuel efficiency and running costs


Diesel wins clearly:


  • - Diesel engines are more efficient (approx. 35–40% vs. 25–30% for petrol)
  • - At the same output, diesel uses around 30–40% less fuel
  • - In Germany, diesel is often cheaper than petrol

Example calculation (at 5 kW continuous power):


  • - Diesel: approx. 1.5–2.0 L/h → cost: ~3,00–4,00 €/h (at 2,00 €/L)
  • - Petrol: approx. 2.5–3.0 L/h → cost: ~4,50–5,40 €/h (at 1,80 €/L)

Over 100 operating hours, diesel saves you 150–240 € in fuel costs.


Service life and durability


Diesel lasts longer:


  • - Diesel engines are designed for 15,000–20,000 operating hours
  • - Petrol engines typically manage 5,000–10,000 hours
  • - Diesel engines run at lower speeds (less wear)
  • - More robust construction designed for continuous operation

Purchase costs


Petrol is cheaper to buy:


  • - Diesel generators cost 50–100% more than comparable petrol models
  • - However, the higher purchase price pays for itself through lower running costs

Break-even calculation: Assuming a diesel generator costs 1.000 € more:


  • - With savings of 1,50 € per operating hour
  • - Break-even after approx. 670 operating hours
  • - With weekly use (4 h): pays for itself after ~3.2 years

Servicing and maintenance


Diesel needs more attention:

  • - Regular oil changes (every 100–200 h)
  • - Fuel filters need replacing
  • - Cleaning the air filter is important
  • - Petrol generators need less maintenance, but wear parts need replacing more often

Noise level


Petrol tends to be quieter:

  • - Petrol generators: 55–75 dB(A)
  • - Diesel generators: 65–97 dB(A)
  • - BUT: Modern diesel inverters (e.g. FME XG-SF 5600D) with sound insulation achieve similar levels to petrol models

Environment and emissions


Modern diesel is cleaner than its reputation:


  • - Modern Stage V engines have very low emission levels
  • - CO₂ emissions per kWh are lower with diesel (better efficiency)
  • - Petrol generators produce more CO and unburnt hydrocarbons
  • - Diesel soot is minimised by particulate filters

Cold-weather performance


Petrol starts better in sub-zero temperatures:


  • - Petrol stays liquid down to -30°C
  • - Diesel can gel from -10°C (summer diesel) or -20°C (winter diesel)
  • - Solution: use winter diesel or fuel additives

Which fuel when?


Choose a diesel generator if:


  • - You need to generate power regularly (weekly/monthly)
  • - You need high output (5 kW and above)
  • - You are planning continuous operation or long runtimes
  • - Low running costs are important
  • - The generator will be used professionally/commercially

Choose a petrol generator if:


  • - You only need power occasionally (1–2 times a year)
  • - Low output (under 3 kW) is enough
  • - Maximum portability is important
  • - Your budget for the purchase is limited
  • - You plan to use it in winter in severe frost

How much power do I need?

The most important question before you buy: how much power does my diesel generator need? A machine that is too small will be overloaded, one that is too big is unnecessarily expensive. Here is how to work out what you need:


Step 1: List all appliances


Write down all the devices you want to run at the same time, together with their rated power (you will find this on the rating plate or in the operating manual).


Example: detached house (backup power):


  • - Fridge: 150 W
  • - Chest freezer: 200 W
  • - LED lighting (10 lamps): 100 W
  • - Router/internet: 20 W
  • - Laptop: 65 W
  • - Heating circulation pump: 80 W
  • - TV: 120 W
  • - Total: 735 W

Step 2: Allow for starting currents


Many devices with electric motors (fridges, pumps, circular saws) need 2–7 times their rated power for a few seconds when switched on.


Starting current multipliers:


  • - Refrigeration appliances: factor 3–4
  • - Pumps: factor 3–5
  • - Compressors: factor 4–6
  • - Circular saws: factor 5–7
  • - LEDs/heaters: factor 1 (no starting current)

Example calculation:


  • - Fridge: 150 W × 3 = 450 W starting power
  • - Chest freezer: 200 W × 3 = 600 W starting power
  • - Largest starting current: 600 W

Step 3: Add a safety margin


Add the largest starting current to the total rated power and multiply by 1.2 (20% reserve):


Our example calculation:


  • - Total rated power: 735 W
  • - Largest starting current: 600 W
  • - Subtotal: 1,335 W
  • - With 20% margin: 1,335 W × 1.2 = 1,602 W


→ A generator with at least 2,000 W (2 kW) would be recommended.


Typical power requirements at a glance


Application
Recommended generator output
Camping/motorhome
1.5–3 kW
Summer house
2–4 kW
Detached house (essential supply)
5–8 kW
Detached house (full supply incl. cooker)
10–15 kW
Small building site
5–10 kW
Large building site
15–30 kW
Business (continuous operation)
20 kVA and above


kW vs. kVA: what is the difference?


On larger generators you will often see the figure given in kVA (kilovolt-amperes) instead of kW (kilowatts):


  • - kW = active power: The electrical power you can actually use
  • - kVA = apparent power: The maximum power produced by the generator

Conversion: kW = kVA × cos φ (power factor, usually 0.8)


Example: A 20 kVA generator delivers around 20 × 0.8 = 16 kW of usable power.


Important note on inverter generators


Thanks to their electronic control, inverter generators such as the FME 8000iD have a higher overload tolerance. They handle starting currents better, so you can calculate with a smaller safety margin.

Key buying criteria for diesel generators

Now that you know how much power you need, look out for these technical features when choosing your generator:


1. Inverter vs. AVR – which voltage regulation is right for you?


AVR (automatic voltage regulator):


  • - Mechanical/electromagnetic voltage regulation
  • - Stable voltage ±5%
  • - More robust, less prone to faults
  • - Cheaper to buy
  • - Ideal for: tools, building site equipment, lighting, heaters

Inverter technology:


  • - Electronic conversion into clean sine wave power
  • - Extremely stable voltage ±1%
  • - Less noise (ECO mode possible)
  • - Safer for sensitive electronics
  • - Ideal for: laptops, TVs, medical equipment, UPS systems, IT equipment

Our recommendation: If you mainly want to run household appliances, computers or other sensitive electronics, invest in an inverter such as the FME 8000iD. For building sites and heavy-duty applications, an AVR model such as the FME SP7000D is sufficient.


2. Single-phase (230V) vs. three-phase (400V)


230V single-phase power:

  • - Standard in households
  • - For normal household appliances
  • - Simpler installation

400V three-phase power:


  • - For high-power appliances (cookers, instantaneous water heaters, workshop machines)
  • - Higher outputs possible
  • - Required for many commercial devices

Same Power technology (e.g. FME 8000iD):


Modern models provide both voltages at the same time – you can run 230V and 400V devices in parallel without splitting the power. This is particularly handy for mixed applications.


3. Noise level and sound insulation


Diesel generators have a reputation for being noisy. Modern models, however, are much quieter:


Typical noise levels:


  • - Without sound insulation: 85–97 dB(A) at 7 m
  • - With soundproof enclosure: 65–75 dB(A) at 7 m
  • - Diesel inverter (ECO mode): 60–70 dB(A) at 7 m

For comparison:


  • - 60 dB: normal conversation
  • - 70 dB: vacuum cleaner
  • - 80 dB: road traffic
  • - 90 dB: lorry

Tip for quieter operation: The FME XG-SF 5600D has an ECO mode that automatically adjusts the engine speed to the load. At low load, the engine runs more slowly and much more quietly.


4. ATS (automatic transfer switch) – automatic changeover


For home backup power systems, an ATS input is worth its weight in gold:


  • - In a power cut, the generator starts automatically
  • - After 10–30 seconds, the supply switches over to generator power
  • - When mains power returns, the system automatically switches back
  • - The generator idles for another 5–10 minutes (cooling down) and then switches off

Models with ATS function: FME 8000iD (integrated), FME SimpleGen series (can be retrofitted as an option)


5. Fuel consumption and tank size


Guide consumption figures for diesel generators:


  • - At 50% load: approx. 0.25–0.35 L/kWh
  • - At 75% load: approx. 0.30–0.40 L/kWh
  • - At 100% load: approx. 0.35–0.45 L/kWh

Runtime calculation:


Example FME XG-SF 5600D (20 L tank, 5 kW):


  • - At 2.5 kW load (50%): approx. 1.5 L/h consumption → 13 h runtime
  • - At 5 kW load (100%): approx. 2.0 L/h consumption → 10 h runtime

Tip: For longer power cuts, external fuel tanks or tank connections are important. The FME SimpleGen industrial generators have tanks from 62 L to 820 L.


6. Electric start vs. recoil start


Electric start:


  • - More convenient, especially with large engines
  • - Battery required (maintenance!)
  • - Can be combined with an ATS
  • - Recommended from 5 kW output

Recoil start:


  • - Reliable, no battery needed
  • - More physically demanding
  • - Sufficient for small generators up to 3 kW

Our recommendation: For regular use or backup power applications, electric start is a must.


7. Emission standards: Stage IIIA, Stage V


Stricter emission standards for diesel engines have applied in the EU since 2021:


  • - Stage IIIA: Older standard, still found on many existing models
  • - Stage V: Current EU standard (since 2021), very low emissions
  • - Particulate filter: Reduces fine dust by up to 97%

Important: In Germany, private diesel generators do not need to be registered or approved, but Stage V is recommended for environmental reasons.


8. Safety features


Modern diesel generators should have at least the following protective functions:


  • - Overload protection: Automatic shutdown in the event of overload
  • - Low-oil shutdown: The engine stops if the oil level is too low
  • - Overheating protection: Temperature monitoring
  • - RCD (residual current device): Protection against electric shock (for permanently installed systems)
  • - CO shutdown: On inverter models, for safety in enclosed spaces

Which diesel generator is right for you?

Diesel backup generator for detached houses


Requirements:


  • - 5–10 kW output (essential supply) or 10–15 kW (full supply)
  • - Three-phase (400V) for an electric cooker and instantaneous water heater
  • - ATS function for automatic changeover
  • - Inverter technology for sensitive electronics
  • - Low noise (75 dB maximum)

Our recommendation:


FME 8000iD

-> Click here to view the FME 8000iD


  • - 8,000 W output
  • - 230V AND 400V at the same time (Same Power)
  • - Integrated ATS input
  • - Inverter quality for computers, TVs, routers
  • - Automatic CO shutdown

In a power cut, this generator supplies all the important appliances in an average detached house. Fridge, chest freezer, heating, lighting, internet and even the cooker can all run at the same time.


Installation tip: Have the connection to your home's electrical system carried out by an electrician. A transfer switch (changeover device) prevents dangerous backfeeding into the public grid.


Diesel generators for building sites and trades


Requirements:

  • 5–15 kW depending on the tools
  • Robust and dust-protected
  • 400V for circular saws, cement mixers, compressors
  • Durable engine for frequent use
  • Wheel kit/carrying handles for portability

Our recommendation:


FME SP7000D

-> Click here to view the FME SP7000D


  • - 7,000 W with AVR technology
  • - Same Power: 230V and 400V
  • - Runs on diesel OR heating oil
  • - Robust steel frame
  • - Electric start

For larger building sites or continuous operation:


FME SimpleGen B20


  • - 20 kVA (16 kW) continuous power
  • - Professional Baudouin engine
  • - Water-cooled design for 24-hour operation
  • - 62 L tank
  • - 4-stage protective circuit

Practical tip: A 7 kW generator can typically run the following building site equipment at the same time:


Circular saw (2,000 W) + hammer drill (1,200 W) + lighting (500 W) + compressor (2,000 W) = 5,700 W


Diesel generators for camping and motorhomes


Requirements:


  • - Compact design
  • - Quiet (70 dB maximum)
  • - Lightweight (under 100 kg)
  • - 2–5 kW is sufficient
  • - Inverter for laptops and smartphones
  • - Fuel compatibility (diesel/heating oil)

Our recommendation:


FME XG-SF 5600D Carbon

-> Click here to view the FME XG-SF 5600D Carbon


  • - Compact: 840 × 570 × 700 mm
  • - 5,000 W continuous power, 5,500 W short-term
  • - Runs on diesel AND heating oil
  • - ECO mode for quiet operation
  • - Electric start
  • - 20 L tank (up to 13 h runtime)

Perfect for off-grid camping – you can run an air conditioner, fridge, coffee machine, kettle and laptop at the same time.


Camping tip: Use ECO mode at night. At a load of 1–2 kW, the generator runs much more quietly and saves fuel.


Diesel generators for business and industry


Requirements:


  • - 20 kVA and above
  • - 24-hour continuous operation possible
  • - Water cooling
  • - Automatic control (ATS)
  • - Remote monitoring
  • - Easy to maintain
  • - EU Stage V compliant

Our recommendation:


FME SimpleGen series (20–2,750 kVA)


  • - European quality engines (Baudouin)
  • - Nekra or Linz alternators
  • - Water-cooled for continuous operation
  • - 4-stage protective circuits
  • - Optional soundproof enclosure
  • - Custom configuration available

Reference projects: FME SimpleGen generators supply power to, among others:


  • - Upper Bavaria Police (Polizeibehörde Oberbayern)
  • - German Federal Ministry of the Interior
  • - THW (German Federal Agency for Technical Relief)
  • - Hanseatic City of Wismar

Not sure what kind of generator you need? Get in touch at any time and we will give you personal, tailored advice.
-> Contact us here

Maintenance and care: how to make your diesel generator last 20+ years

A diesel generator is a long-term investment. With proper maintenance, it will last for decades. Here are the most important maintenance tasks:


Regular maintenance


After every use (0–5 h):


  • - Check the fuel level
  • - Visual check for leaks
  • - Clear dirt from the cooling air inlets

Every 50 operating hours or 6 months:


  • - Change the engine oil (after 20 h during running-in)
  • - Check the oil level
  • - Clean/replace the air filter
  • - Check the fuel filter

Every 100–200 operating hours or 12 months:


  • - Change the engine oil (under moderate conditions)
  • - Replace the fuel filter
  • - Check the spark plugs (if fitted)
  • - Charge and check the battery (electric start models)
  • - Check that all bolts are tight

Annually (even if not used):


  • - Run the generator under load for at least 30 minutes
  • - Flush the fuel system
  • - Check all seals
  • - Check the coolant (water-cooled models)

Engine oil: which type and how much?


Recommended oil specifications:


  • - Classification: API CF-4 or higher (diesel engine oil)
  • - Viscosity: 15W-40 (all-round) or SAE 30 (warm climates)
  • - Synthetic oil: 5W-40 for winter operation

Oil capacity of typical models:

  • - FME XG-SF 5600D: approx. 1.6–1.8 L
  • - FME 8000iD: approx. 1.8–2.0 L
  • - FME SimpleGen B20: approx. 6–8 L

Important: Never overfill with oil! Check the oil level with the dipstick when the engine is cold (do not run the generator).


Fuel storage and stability


Shelf life of diesel:


  • - Fresh diesel: 6–12 months
  • - With stabiliser: up to 24 months
  • - After 12 months: oxidation and algae growth possible

Tips for long-term storage:


  1. - Fill the tank completely (reduces condensation)
  2. - Add fuel stabiliser
  3. - Store in a cool, dark place
  4. - Before using after storage: replace the fuel filter

For longer periods out of use (>3 months):


  • - Empty the tank or run the fuel completely dry
  • - Treat the carburettor/injection system with preservation spray

Winter operation: how to start your diesel in frost


Problem: Diesel contains paraffins that crystallise (gel) in the cold.


Solutions:


  1. 1. Use winter diesel (available at filling stations from November to March) – flows down to -20°C
  2. 2. Anti-gel additives for extreme frost
  3. 3. Store the generator frost-free (garage, shed)
  4. 4. Let it warm up: In cold weather, idle for 5 minutes before applying a load

When to go to a specialist workshop?


You should leave the following work to a professional:


  • - Injection pump adjustment
  • - Valve clearance adjustment
  • - Cylinder head work
  • - Electrical fault-finding
  • - ATS installation

Conclusion: the right diesel generator for every need

​​​​​

Diesel generators are the most economical and reliable solution for regular power generation, backup power and professional applications. The higher initial investment pays for itself through low running costs, a long service life and high fuel efficiency.


With the right sizing, regular maintenance and high-quality components, your diesel generator will be a reliable companion for 20+ years.


Why buy from Kipor.org?


✅ 18+ years of experience – specialising in generators since 2007

✅ Direct advice – personal contact, no call centres

✅ Fast delivery – delivered in the shortest possible time

✅ In-house workshop – professional service in Versmold, Germany

✅ Spare parts in stock – for models from 2007 onwards

✅ Fair prices – no middlemen

✅ Pay in instalments – flexible financing


Contact and advice


Not sure which generator suits your requirements? The Kipor team will be happy to advise you:


📞 Phone: +49 (0)5423 477400
📧 Email: info@kipor.org
🌐 Website: www.kipor.org
📍 Address: Kipor.org GmbH, Industriestraße, Versmold, Germany


Opening hours: Mon–Fri: 8:00 am–5:00 pm