Marsun MVBG3.5PI 3 kW Petrol and LPG Generator

The Marsun MVBG3.5PI is a single-phase dual-fuel generator that runs on unleaded petrol or LPG (propane-butane): 3 kW rated power (3.5 kW maximum), 230 V, 50 Hz, an air-cooled engine, AVR voltage regulation and manual start. With the 13 l petrol tank the manufacturer states up to 6.5 hours of running at 100% load. It is meant for backup power, off-grid and hybrid solar systems, building work and the garden plot.

Technical specifications

Download the manufacturer datasheet (PDF)

What is a 3 kW petrol and LPG generator used for?

The MVBG3.5PI is a 3 kW portable generator for places where the grid fails or does not exist. Typical uses:

• Backup power for a home when the grid goes down
• An extra source for a solar PV system and energy storage in off-grid and hybrid systems
• Power tools on building and renovation work
• A summer house or garden plot
• Camping, a camper van and outdoor events
• Running on whichever fuel you have to hand: petrol or an LPG cylinder

How much fuel does the MVBG3.5PI use and how long does it run on a full tank?

The manufacturer states that on a full 13 l petrol tank the MVBG3.5PI runs for up to 6.5 hours at 100% load. Plan on this manufacturer figure; it matters more than the calculation below.

A rough calculation on petrol: ≤ 395 g/kWh × 3 kW = about 1.19 kg of petrol per hour, or about 1.6 l/h (1.19 kg ÷ 0.74 kg/l). At that rate the 13 l tank would last about 8 hours, but this is only a theoretical result, so the manufacturer’s 6.5 hours is the safer figure to plan with. At a lower load it burns less fuel.

The manufacturer does not give LPG consumption, so we do not calculate it. On LPG the generator is fed from a separate cylinder through a dedicated pressure regulator, so running time depends on the cylinder size.

Can the MVBG3.5PI be used with a hybrid inverter?

The manufacturer states compatibility with Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters. In a hybrid system, when the solar PV system produces too little and the battery runs flat, the generator powers the building’s appliances and charges the batteries.

Note: the MVBG3.5PI is started by hand on both petrol and LPG, so it does not start by itself on an inverter signal. If you need automatic start, choose a model with electric start and an ATS.

How do you connect a generator to a house or site?

A generator must never be plugged into the house’s wall sockets. It is connected to the site’s internal wiring only through a fixed connection with a grid/0/generator changeover switch, and that must be done by a qualified electrician. ESO (Lithuanian grid operator) states:

“A generator may be connected to the internal electrical network of a whole building only by installing a fixed connection and measures that ensure the voltage produced by the generator is not fed into ESO’s networks… Entrust this work only to qualified specialists.”

ESO — Recommendations for installing a backup power source

On the same page ESO advises choosing the power according to your connection capacity and real load.

We handle it for you. We select the equipment for your site, deliver anywhere in Lithuania, install and connect it.

What load can you connect to a single-phase 3 kW generator?

The MVBG3.5PI supplies only single-phase 230 V, and all of its power comes from that one phase. The total power of everything connected, including starting currents, must not exceed the 3 kW rated power.

Pumps, fridges and compressors draw 2 to 5 times more current when they switch on than when running, so allow a margin for them. Running at 100% load for a long time is not recommended: the optimum for engine and alternator life is 75 to 80% of rated power, which for the MVBG3.5PI is about 2.25 to 2.4 kW.

If the generator charges batteries, add the charging power to the building’s demand and multiply the result by 1.25. For the MVBG3.5PI the combined demand of the building and battery charging should come to no more than about 2.4 kW.

On LPG the engine output is about 10% lower than on petrol, because LPG has a lower heating value. If the generator will mostly run on gas, keep an extra 10% margin in your calculation. Temperatures above 25 °C and high altitude can also reduce the maximum power.

The manufacturer states inverter technology and a clean sine wave suitable for sensitive electronics such as laptops.

What to know before buying

• The manufacturer states a noise level of ≤ 97 dB. A sound-insulating canopy is not mentioned in the manufacturer’s data, so choose the position with neighbours and rest areas in mind.
• Weight is 27 / 30 kg and dimensions are 485 × 450 × 495 mm. The frame has integrated handles, so it is easy to carry.
• There is no ATS and no electric starter: start is manual with the recoil cord. After starting, let it run for 3 to 5 minutes without a load.
• Petrol must be clean unleaded with an octane rating of at least 95; up to 10% ethanol is permitted. For gas use only clean LPG (propane-butane) and the dedicated pressure regulator.
• Stand the gas cylinder upright, at least 1 m from the generator and out of the stream of hot exhaust gases, and do not keep it in a cellar or other below-ground room. Check the oil level and the gas system for leaks before every start.
• When you finish running on gas, first close the cylinder valve, wait for the engine to stop by itself, and only then switch off the engine switch.
• The generator is delivered without oil: before the first start fill 0.6 l of SAE 10W-30. Use it outdoors only, and not in rain or snow.

Frequently asked questions

How long does the Marsun MVBG3.5PI run on a full tank?

The manufacturer states up to 6.5 hours of continuous running at 100% load, with a 13 l petrol tank. On LPG the running time depends on the cylinder size.

How much fuel does the MVBG3.5PI use?

According to the manufacturer, no more than 395 g/kWh. On petrol at a full 3 kW load that is roughly 1.19 kg, or 1.6 l, per hour. LPG consumption is not given.

Can the MVBG3.5PI run on LPG?

Yes. The MVBG3.5PI runs on unleaded petrol or LPG (propane-butane) through a pressure regulator, but its output on gas is about 10% lower.

Does the MVBG3.5PI have an ATS or automatic start?

No. The MVBG3.5PI is started by hand and has no built-in automatic transfer switch (ATS). For automatic backup you need a model with electric start.

Which inverters is the MVBG3.5PI compatible with?

The manufacturer lists Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters. Hybrid Energy matches the exact connection to your system.

Can a generator be connected straight to the house’s distribution board?

No. Only through a fixed connection with a changeover switch so that voltage cannot reach the ESO grid, and only by a qualified specialist. Hybrid Energy installs such a connection.

Is a 3 kW generator suitable for a house, a garden plot or building work?

Yes, the 3 kW MVBG3.5PI suits backup power for a home, a summer house, power tools on building sites and camping.

How loud is the MVBG3.5PI?

The manufacturer states ≤ 97 dB, and a sound-insulating canopy is not mentioned in its data. The generator is used outdoors only.

How much single-phase load can be connected to the MVBG3.5PI?

Up to 3 kW from one 230 V phase, including starting currents. For long running, about 2.25 to 2.4 kW (75 to 80% of rated power) is optimal.

Do you deliver and install the MVBG3.5PI?

Yes. Hybrid Energy delivers the MVBG3.5PI anywhere in Lithuania, selects the changeover solution, installs and commissions it. The consultation before buying is free.

Sources

• Marsun MVBG3.5PI manufacturer datasheet (PDF), checked 2026-10-26
• ESO, recommendations for installing a backup source, checked 2026-10-26