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How to Choose the Right Generator for Your Power Needs?

Before purchasing a generator, one often wonders what to consider when selecting a power unit. Here, you will find out what questions to answer and what to pay attention to when choosing the right generator.

Diesel, gasoline, or perhaps gas-Powered? Choosing a generator based on the type of fuel.

The engine plays a crucial role in a generator. Its design and reliability determine the lifespan of the generator. In this regard, either a diesel or gasoline engine is suitable. Generators with gasoline engines are more affordable, relatively space-saving, and produce less noise, although the lifespan of a gasoline engine is shorter compared to a diesel engine. Moreover, a gasoline engine can be retrofitted with a special gas system, allowing it to run on liquefied gas (propane-butane). In comparison to a regular gasoline generator, such an LPG/petrol generator enables a more environmentally friendly and cost-effective operation by utilizing liquefied gas.

The diesel engine, on the other hand, boasts significantly longer lifespan. Key advantages of diesel generators include cost-effectiveness and durability. Furthermore, diesel fuel is cheaper and safer than gasoline. Diesel generators can also operate continuously for longer periods compared to gasoline generators. However, there is a notable drawback: diesel generators are much more expensive than gasoline generators with the same rated power, even though the price difference is offset over time due to the cheaper diesel fuel. It should also be noted that diesel generators have a higher noise level. Hence, it is recommended, budget permitting, to opt for models with a sound-insulated casing or choose an appropriate location for the generator to avoid noise disturbances. Additionally, due to their larger size and higher weight, diesel generators require more space.

Inverter generator or conventional generator: Which one to choose?

Among gasoline and LPG/petrol generators, there are both conventional generators and inverter generators. The main difference between an inverter generator and a conventional generator lies in the fact that the latter directly draws voltage from the windings, while the inverter generator electronically generates voltage and regulates it with a built-in inverter module with microprocessor control. This results in a pure sine wave with a stable frequency of 50 Hz and a voltage of 230 V in the socket. This high-quality power is especially crucial for electronics and electronically controlled devices such as gas heating boilers and other sensitive equipment. Other advantages of Könner & Söhnen inverter generators include their smaller size and lighter weight, as well as the ECONOMY mode, available in most models, which reduces fuel consumption by up to 50% under light loads.

How to calculate the power requirement of the generator?

Before choosing a generator, you must first calculate the total power of the electrical appliances that your generator will simultaneously supply with electricity. When calculating the total power of the electrical appliances, always consider the starting power of each electrical device. This is especially important for power tools, air conditioners, pumps, and other devices with an electric motor. For some of these devices, the starting power can be several times higher than the rated power and must be taken into account. To determine the starting power (or starting current) of your device, you can follow these steps:

  1. Obtain it from the user manual or the manufacturer;
  2. Determine it with a special measuring device;
  3. Approximate it using the table below (to calculate the starting power, find the corresponding factor from the table and multiply it by the rated power of your electrical appliance).


Device Rated Power (W) Correction Factor Starting Power (W)
Iron 1200 1 1200
Hair Dryer 1000 1 1000
Coffeemaker 800-1500 1 800-1500
Electric Stove 800-2000 1 800-2000
Gas Oven 1000-2000 1 1000-2000
Toaster 600-1500 1 600-1500
Grill 1200-2300 1 1200-2300
Refrigerator 100-150 3.5 350-525
Water Pump 500-1000 5 2500-5000
Vacuum Cleaner 800-1500 1.3 1040-1950
Television 100-400 1 100-400
Electric Kettle 1200-2000 1 1200-2000
Gas Boiler 150-250 2.5 375-625
Heater 1000-2000 1 1000-2000
Air Conditioner 1000-5000 3.5 3500-12250
Fluorescent Lamp 30-120 1.5 45-180
Incandescent Lamp 100-500 1 100-500
Hammer Drill 600-1600 1.2 720-1920
Electric Drill 400-800 1.3 520-1040
Grinder 300-1100 1.3 390-1430
Circular Saw 750-1600 1.3 1000-2000
Jigsaw 250-600 1.3 325-900

After calculating the total power, you must also consider the power reserve. When using the generator, pay attention to the power factor. As this cannot be determined without special measuring devices and is not always specified in the technical data by manufacturers, we recommend not to load the generator with more than 70-80% of its rated power. The generator must cover both the active and reactive power of the consumers.

For more information on this topic, please refer to the Facebook post and the video "How powerful should a generator be?"

Starting type. Which one should I choose?

There are three starting types:

  • Manual start (with a recoil starter). To manually start the generator, pull the starter cord quickly and forcefully. The manual starter is only used in generators with low power, as manually starting a generator with a power of over 5 kW requires significant effort.
  • Electric start. The generator can be started by turning the ignition key on the control panel. The electric start is suitable for continuous operation, making it much more convenient to use.
  • Auto start with an ATS unit. This starting type is required when the generator functions as an emergency power source with automatic start. In this case, the built-in or external ATS unit (automatic transfer switch to emergency power) starts the generator automatically in the event of a main power failure and shuts it off when the power is restored. Important! Generators with automatic start must be placed in a heated room. In low temperatures (below +5°C), it can be difficult to start a generator manually, and the automatic start may fail!

An electric starter and an automatic start provide more convenience when using a generator. Therefore, when choosing a powerful generator, make sure it has an electric start since it is challenging to start a high-powered generator manually.

Which generator is better: Three-Phase or Single-Phase?

Some buyers believe that three-phase generators are versatile. There is also an opinion that a three-phase power generator is the best choice because what is more expensive is also better. However, this is not the case here. When deciding between a single-phase and three-phase generator, consider the consumers you will connect to the generator. If only single-phase consumers will be connected to the generator, then you only need a single-phase generator! Single-phase generators are ideal for holiday homes since all electrical household appliances used there (televisions, refrigerators, microwave ovens, kettles) are single-phase consumers. It should be noted that electrical consumers such as an electric stove, a powerful instantaneous water heater, air heaters, an electric boiler, or a sauna are only connected to the normal three-phase household power grid and, in principle, are a series of single-phase heating elements, so they must be powered by a 230V generator.

Three-phase generators should only be used to supply three-phase consumers that require a three-phase power supply or other consumers that symmetrically load all three phases of the generator. These include motors or pumps that require exclusively three-phase power (400 V). Heat pumps usually use mixed internal power consumers, the supply of which through a three-phase generator is generally not safe.

To prevent high-powered 400V consumers (especially those with phase-angle control) from damaging sensitive 230V consumers, we generally recommend providing a separate power supply for single-phase (230 V) and three-phase (400 V) consumers in the household.

However, if you need a universally applicable generator that is suitable for both single-phase and three-phase consumers, consider Könner & Söhnen models with the code "1/3" (KS 7000E 1/3, KS 10000E 1/3, etc.) in their name. They are equipped with a VTS function for switching between single-phase and three-phase operation.

Air cooling or water cooling

Air-cooled generators are cooled by normal heat exchange between the motor surfaces and ambient air. These generators have engines with a speed of about 3000 rpm.

Water-cooled generators are more powerful. They are equipped exclusively with a diesel engine, which has a significantly longer lifespan. These units can also be operated continuously for much longer periods than conventional generators. Due to their high weight, these power units are used as permanent, independent power sources in country houses or facilities.

Synchronous generator or asynchronous generator

Before choosing a generator, you should consider the devices you want to power with it.

Asynchronous generators cannot maintain a stable voltage and frequency when switching on and off high-power consumers. However, they can withstand short-term short circuits and have a large output current range. These properties are particularly advantageous when operating certain devices (e.g., welding machines). Asynchronous generators are also used in power generation plants.

Synchronous generators produce a more stable voltage and can handle the starting currents of household appliances with electric motors. These generators are excellent for providing emergency power to homes, offices, vacation homes, cooling systems, and construction sites. While they can tolerate short-term overloads, they should be protected from dirt and water. A synchronous generator, whose power is lower than that of an asynchronous generator, is sufficient for operating electronic household appliances and construction tools.

Asynchronous generators are specific to certain tasks, so most household generators are synchronous generators. Therefore, we recommend choosing these generators for your household use. All conventional (non-inverter) generators from Könner & Söhnen are synchronous generators.

Noise level

The sound level of the generator should be considered when choosing a location for installation. Diesel generators usually produce more noise than gasoline models. Additionally, inverter generators have an ECONOMY mode that, when activated, reduces the engine speed and noise level.

Könner & Söhnen generators comply with all European standards, including noise levels. For comfort reasons, generators should be installed in a location away from people. To reduce noise, you can place the generator in a special container equipped with a foundation, ventilation, and an exhaust gas extraction system. However, it is easier and more economical to choose a diesel or inverter generator with a factory-fitted soundproof enclosure.

Purpose of a generator: How to choose a generator for your needs

If you need a generator for camping, then a lightweight and space-saving inverter generator (up to 2 kW) with a low noise level is the right choice.

For your vacation home where you spend most of the summer or renovate (extensions), a gasoline generator with a power of up to 5 kW is sufficient. For a country house, a gasoline or diesel generator with air cooling is the best alternative power source (in case of a power outage).

If your country house or business premises require long-term power supply, you will need a powerful diesel generator with water cooling (up to 30 kVA).

Watch our video on "For whom are Könner & Söhnen generators suitable? Top 10 application scenarios."

Selecting a generator for a solar power system

To ensure uninterrupted power supply to the solar power system during shortages or emergencies, different types of generators are used. Diesel generators are suitable for large solar power systems due to their power, high reliability, and long lifespan. However, for typical household solar power systems, conventional or inverter-controlled gasoline generators are the right choice. However, if a generator is needed for a household solar station with 48V batteries, the KS 48V-DC Direct Current Generator from Könner & Söhnen is the optimal solution. This generator has many advantages and is specifically designed for this application.

For more information about the generator for a solar power system and the design of the connection scheme depending on the availability of batteries and the type of inverter, you can refer to the article "Emergency Power Supply for Solar Power Systems" (Note: The link provided here is not functional as it is a relative link within the context of the original website).

Assistance with generator selection

Now you know what to consider when choosing a generator. As mentioned in the article, there are several aspects to consider in selecting the right power generator. However, it's essential to exercise caution during this process because choosing the wrong generator may render it useless for its intended purpose and could even damage connected devices. Therefore, we always recommend seeking assistance from knowledgeable sales representatives when purchasing a generator.

If you have any further questions about generators or are unsure if our generator is suitable for your specific needs, please contact our support team. On the Contact page, you will find phone numbers and email addresses to help you with choosing the right generator.

Wishing you a successful purchase!