Why you need a gasoline or gas generator
Backup power has long ceased to be a luxury. In Ukraine, where power outages occur regularly, a generator has become essential equipment for a private home, cottage, small business, or construction site. Gasoline and gas generators provide independence from the main grid and keep household appliances, heating, lighting, and industrial equipment running even during extended blackouts.
Before buying a power station, it is worth understanding the differences between fuel types, how each generator works, and how to calculate the required power capacity correctly. In this article, we take an in-depth look at gasoline, gas, diesel, and inverter generators, compare their specifications, and help you choose the best option for your specific needs.
Comparison table: gasoline, gas, and diesel generators
To get a quick overview of the differences, review this summary table of the main parameters for three generator types:
| Parameter | Gasoline | Gas | Diesel |
|---|---|---|---|
| Equipment cost | Low — most affordable option | High — more complex design | Medium-high |
| Fuel cost | Medium (A-92/A-95 gasoline) | Low (natural or liquefied gas) | Medium (diesel fuel) |
| Engine life | 500–3,000 hours | 4,000–8,000 hours | 5,000–40,000 hours |
| Noise level | 65–80 dB | 55–72 dB | 75–95 dB |
| Power output | 1–15 kW | 2–20 kW | 3–200+ kW |
| Cold start | Easy, down to -20 °C | Difficult at low gas pressure | Requires preheating below -10 °C |
| Portability | High — compact and lightweight | Low — requires gas line or tank | Low — large and heavy |
| Continuous operation | 6–10 hours (breaks needed) | Unlimited when connected to gas main | Up to 24 hours or more |
| Eco-friendliness | Medium — CO, HC in exhaust | High — minimal harmful emissions | Low — soot, nitrogen oxides |
| Recommended use | Cottage, trips, short-term backup | Home, commercial property, constant power | Industrial, long-term backup |
Gasoline generators: how they work and key features
A gasoline generator is the most popular type of portable power station. An internal combustion engine drives the generator rotor, converting mechanical energy into electrical energy. The design is straightforward and proven over decades: a fuel tank, carburetor or fuel injector, four-stroke (less commonly two-stroke) engine, and a synchronous or asynchronous alternator.
Advantages of gasoline generators
- Affordable price. A 3 kW gasoline generator costs significantly less than a gas or diesel equivalent. For most household applications, this is the most cost-effective upfront investment.
- Easy cold-weather starting. Gasoline evaporates well even at sub-zero temperatures, so the engine starts without preheating down to -20 °C.
- Light weight and compact size. A 2–3 kW gasoline generator weighs 25–40 kg. It is easy to transport in a car trunk to a cottage, construction site, or campsite.
- Low noise level. Compared to diesel equivalents, gasoline generators run quieter — within 65–75 dB, which is acceptable for residential areas.
- Easy maintenance. Oil changes, spark plug replacement, and air filter cleaning — that is all the regular maintenance required. No specialized knowledge is needed.
Disadvantages of gasoline generators
- Limited engine life. Budget models require major overhaul after just 500–1,000 hours of operation. More expensive units last up to 3,000 hours, but that is still less than diesel and gas alternatives.
- Not suitable for round-the-clock operation. Manufacturers recommend shutting down a gasoline generator every 6–10 hours for cooling. Continuous operation leads to overheating and accelerated piston wear.
- High fuel consumption. At 75% load, a 3 kW generator consumes 1.2–1.5 liters of gasoline per hour. Over 24 hours, that amounts to 30–36 liters — a significant operating cost.
- Limited fuel shelf life. Gasoline oxidizes within 3–6 months. If the generator sits idle for a long time, the fuel in the tank and carburetor degrades, clogs jets, and may prevent starting.
Gas generators: savings and environmental benefits
A gas generator runs on natural gas (methane) from a main gas pipeline or on liquefied petroleum gas (propane-butane) from cylinders. The operating principle is the same as a gasoline generator — an internal combustion engine drives the alternator — but the fuel system is adapted for gaseous fuel.
Advantages of gas generators
- Low fuel cost. A kilowatt-hour of electricity from a gas generator costs nearly half that of a gasoline generator. For stationary use, this represents significant savings.
- Long engine life. Gas does not create carbon deposits on cylinder walls and valves, nor does it dilute engine oil. This means the engine wears more slowly and lasts 4,000–8,000 hours before major overhaul.
- Continuous operation capability. When connected to a gas main, the generator can run continuously — no need to stop for refueling.
- Eco-friendliness. Exhaust gases contain significantly less carbon monoxide, soot, and carcinogenic substances than gasoline and diesel counterparts. This matters when operating near residential buildings.
- Quieter operation. Gas generators typically run quieter than gasoline models — at 55–72 dB.
Disadvantages of gas generators
- High initial cost. A gas generator costs 20–50% more than a gasoline equivalent of the same power. Additionally, professional connection to the gas pipeline may be required.
- Safety requirements. Gas is an explosive substance. Installing a gas generator indoors requires thorough ventilation, a gas detector, and compliance with fire safety regulations.
- Dependence on gas pressure. At low gas network pressure (common in rural areas), generator output drops noticeably. Liquefied gas in cylinders also presents challenges at low temperatures — propane evaporates poorly below -15 °C.
- Limited portability. A main gas connection ties the generator to one location. Bottled gas is more portable, but a 50-liter gas cylinder weighs about 40 kg — not the most convenient option for transport.
Dual-fuel (bi-fuel) generators
Special attention should be given to generators capable of running on both gasoline and gas. They feature a fuel mode switch and allow you to use whichever fuel is available at the moment. These models combine the portability of a gasoline unit with the economy of a gas unit: you start the generator on gasoline, then switch to gas for extended operation.
Inverter generators: clean sine wave for sensitive equipment
An inverter generator is a separate class of portable power station with an electronic voltage converter. Unlike a conventional generator, where power quality directly depends on engine speed, an inverter generator first produces AC power, then rectifies it to DC, and converts it back to AC — but with perfectly stable parameters.
Why this matters
A conventional generator produces voltage distortion (THD) of 10–25%. An inverter generator delivers THD below 3%, comparable to mains power quality. This is critical for:
- Computers, laptops, servers, and networking equipment.
- Gas boilers with electronic control boards.
- Medical devices (oxygen concentrators, nebulizers).
- Charging stations for power tools and gadgets.
- Industrial equipment with variable frequency drives that require a clean sine wave input.
Inverter generators also feature an Eco mode: the engine automatically adjusts its speed based on current load. At 30% load, the generator consumes half the fuel compared to full speed. This reduces both fuel consumption and noise — at light loads, an inverter generator operates at 50–58 dB, quieter than normal conversation.
Backup power for your home: generator or UPS with battery
During regular power outages, the question arises: what is more effective — a generator or an uninterruptible power supply based on an inverter with battery storage? In reality, these solutions complement rather than compete with each other.
Generator as primary backup source
A generator provides extended power for heavy loads — electric heating, air conditioning, electric stove, water heater. However, it requires 10–30 seconds to start (even with ATS automation), produces noise and exhaust fumes, and needs fuel and regular maintenance.
UPS + battery as instant buffer
An uninterruptible power supply (UPS) switches to batteries in 5–10 milliseconds — practically instantaneously. This protects sensitive equipment from voltage surges when power disappears and returns. But battery capacity is limited: a standard 5 kWh system will keep a refrigerator, router, and lighting running for 4–8 hours.
Optimal setup: generator + UPS + ATS
The most reliable option is a combined system. An automatic transfer switch (ATS) instantly routes power to batteries when the grid fails, then automatically starts the generator after 15–30 seconds. When the generator reaches operating mode, it powers both the loads and recharges the batteries. When mains power is restored, the ATS switches everything back without human intervention.
Generator and variable frequency drive: compatibility and considerations
If you plan to power equipment with a variable frequency drive (VFD) from a generator, there are several technical considerations to keep in mind.
Why a conventional generator may not work
A variable frequency drive rectifies incoming AC to DC at its input, then generates regulated frequency and voltage for the motor at its output. It might seem that input power quality does not matter. But in practice:
- Inrush currents. The VFD input rectifier draws a brief inrush current at startup that can be 5–8 times the rated current. A generator with insufficient power headroom cannot handle this surge — voltage drops, and emergency shutdown may occur.
- Harmonic distortion. The VFD rectifier generates harmonics back into the power supply. In a robust utility grid, this is not a problem, but for a generator with limited capacity, harmonics can cause winding overheating and unstable operation of the automatic voltage regulator (AVR).
- Power headroom. For reliable operation, the generator should have a power rating at least 2–3 times the VFD rated power. In other words, for a 5 kW VFD, you need a generator rated at least 10–15 kW.
Connection recommendations
When powering VFD equipment from a generator, the following practices are recommended:
- Choose an inverter or diesel generator with low total harmonic distortion (THD below 5%).
- Ensure the generator power reserve is at least 200–300% of the VFD rating.
- Enable the soft start function in the VFD settings to limit inrush current.
- Use an input choke or LC filter between the generator and VFD to suppress harmonics.
How to choose a generator: step-by-step guide
Choosing a generator involves several sequential steps. Here is a straightforward algorithm to help you make the right decision:
Step 1: Determine required power
List all appliances the generator needs to power simultaneously. For each one, note the rated power (shown on the nameplate or in the manual) and the starting power. Appliances with electric motors (refrigerators, pumps, compressors) have starting power 3–5 times their rated power. Add a 20–30% margin to the total.
Step 2: Choose fuel type
- Gasoline — for portable and short-term use (cottage, trips, construction).
- Gas — for stationary long-term backup of a home or office with access to a gas main.
- Diesel — for industrial facilities, farms, and 24/7 operation with heavy loads.
- Dual-fuel (gasoline + gas) — a versatile option for those who want fuel flexibility.
Step 3: Determine operating mode
If you need a generator for a few hours during occasional outages, a gasoline model is sufficient. For extended backup of 12+ hours per day, consider a gas or diesel option with greater engine life.
Step 4: Choose start type
- Pull start — cheaper, but requires physical effort and human presence.
- Electric start — convenient push-button or key start.
- Auto-start (ATS) — the generator starts automatically when mains power is lost. The optimal choice for permanent home backup.
Step 5: Consider additional features
- Availability of 220V and 380V outlets (for three-phase equipment).
- Hour meter — helps track maintenance intervals.
- Oil level sensor with automatic shutdown — protects the engine from damage.
- Wheels and handle for easy transport.
- Overload indicator and short-circuit protection.
Common mistakes when choosing a generator
Let us review the typical mistakes generator buyers make and how to avoid them.
Mistake 1: Choosing a generator with no power headroom
A generator constantly running at 90–100% load overheats and wears out quickly. The optimal load is 60–75% of rated power. So if your needs total 3 kW, choose a generator rated at 4.5–5 kW.
Mistake 2: Ignoring inrush currents
A refrigerator consuming 150W draws 600–800W when its compressor starts. If you connect several such appliances simultaneously, the generator may trip. Always account for motor load starting power.
Mistake 3: Placing the generator in an enclosed space
Exhaust gases contain carbon monoxide (CO) — a deadly substance with no color or odor. The generator must operate only outdoors or in a well-ventilated area with exhaust routed outside.
Mistake 4: Using stale gasoline
Gasoline that has sat in a canister for more than 3 months may not provide reliable starting and operation. Before the season, drain old fuel, flush the tank and carburetor. For extended storage, add a fuel stabilizer.
Mistake 5: Neglecting grounding
A generator, like any electrical equipment, requires proper grounding. This protects against electric shock and ensures correct operation of the residual current device (RCD) in your electrical panel.
If you are looking for a reliable backup or off-grid power solution, explore our electrical equipment catalog. Our specialists will help you select the right generator for your specific requirements and calculate the required power capacity.
