Marsun MVB3.5PI 3 kW Inverter Petrol Generator, 22 kg

The Marsun MVB3.5PI is a 3 kW (3.5 kW maximum) single-phase inverter petrol generator, more powerful than the MVB2PI: 2.25–2.4 kW of sustained load (75–80% of rated power), a 6 l tank and a 163 cm³ engine. The trade-off is weight (22 kg against 19 kg for the MVB2PI) and noise (≤ 75 dB against ≤ 73 dB), so choose it when your sustained demand is above 1.44 kW. Start is manual, the 6 l tank runs up to 3.5 hours at 100% load, and the manufacturer states compatibility with Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MVB3.5PI differs from the MVB2PI

Both models are single-phase inverter generators with manual start, AVR and 3.5 hours of running at 100% load. They differ in power, tank size, weight and noise:

Choose the MVB3.5PI if you need 3 kW of rated power, 2.25–2.4 kW of sustained load, or want to run the building and charge batteries at the same time. Choose the Marsun MVB2PI if your sustained load stays within about 1.35–1.44 kW and the lower weight (19 kg) and noise (≤ 73 dB) matter more. At 100% load the tank lasts the same time (3.5 hours), but the MVB3.5PI burns more fuel in that time: at rated load roughly 1.6 l/h against 0.96 l/h for the MVB2PI.

How much fuel does the MVB3.5PI use and how long does it run on a full tank?

The manufacturer states plainly that on a full 6 l tank the MVB3.5PI runs for up to 3.5 hours at 100% load. Plan on this manufacturer figure; it matters more than the calculation below.

A rough calculation from the datasheet: ≤ 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 6 l tank lasts about 3.7 hours. That is close to the manufacturer’s figure, but the stated 3.5 hours is the safer one to plan with. At a lower load it burns less fuel and the tank lasts longer.

Can the MVB3.5PI 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 MVB3.5PI is started by hand, so it does not start by itself on an inverter signal. You start the generator yourself; 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 MVB3.5PI 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 MVB3.5PI 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 MVB3.5PI the combined demand of the building and battery charging should come to no more than about 2.4 kW. Temperatures above 25 °C and high altitude can reduce the maximum power.

The manufacturer states inverter technology and a clean sine wave, so sensitive electronics such as laptops, desktop computers and precision measuring instruments can be connected.

What to know before buying

• The noise level is ≤ 75 dB. A sound-insulating canopy is not mentioned in the manufacturer’s data, so choose the position with neighbours in mind.
• The generator weighs 22 kg and measures 560 × 380 × 585 mm, so it is easy to take to the garden, a building site or a campsite.
• There is no ATS and no electric starter: start is manual with the recoil handle.
• The fuel is clean unleaded petrol with an octane rating of at least 95; up to 10% ethanol is permitted. Do not mix petrol with oil.
• The generator is delivered without oil: before the first start fill 0.45 l of SAE 10W-30. The first oil change is after 5 running hours, then every 50 to 100 hours or once a season, and the air filter and spark plug are checked every 50 hours.
• Use it outdoors only, leaving at least 1 m of free space on all sides, and not in rain or snow: the exhaust gas contains carbon monoxide.

Frequently asked questions

How long does the Marsun MVB3.5PI run on a full tank?

The manufacturer states up to 3.5 hours of continuous running at 100% load, with a 6 l tank. At a lower load the tank lasts longer.

How much fuel does the MVB3.5PI use?

According to the manufacturer, no more than 395 g/kWh. At a full 3 kW load that is roughly 1.19 kg, or 1.6 l of petrol, per hour.

Does the MVB3.5PI have an ATS or automatic start?

No. The MVB3.5PI 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 MVB3.5PI 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.

How loud is the MVB3.5PI?

The manufacturer states ≤ 75 dB. The generator is used outdoors only, with at least 1 m of free space around it.

How much single-phase load can be connected to the MVB3.5PI?

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.

How does the MVB3.5PI differ from the MVB2PI?

The MVB3.5PI has 3 kW of rated power, weighs 22 kg and is rated ≤ 75 dB, while the MVB2PI has 1.8 kW, 19 kg and ≤ 73 dB. The manufacturer states up to 3.5 hours of running at 100% load for both.

Do you deliver and install the MVB3.5PI?

Yes. Hybrid Energy delivers the MVB3.5PI anywhere in Lithuania, selects the changeover solution, installs and commissions it. The consultation before buying is free.

Sources

• Marsun MVB3.5PI manufacturer datasheet (PDF), checked 2026-10-26
• ESO, recommendations for installing a backup source, checked 2026-10-26