Marsun MHD40 40 kW Three-Phase Diesel Generator with ATS

The Marsun MHD40 is a 40 kW (44 kW maximum) three-phase diesel generator with a built-in ATS and a heated fuel unit, meant for a load of up to about 30–32 kW. Compared with the 30 kW MHD30 it has 10 kW more power, a heated fuel unit, a higher weight (850 kg) and larger dimensions (2400 × 1000 × 1300 mm), but the same 70 l tank. That is why the rough calculation for the full 40 kW load gives only about 7.2 h per tank, less than the manufacturer’s 8 h; for longer running without refuelling, consider the optional auxiliary tank or the MHD50 with its 120 l tank.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MHD40 differs from the MHD30 and MHD50

The manufacturer states up to 8 h of running for all of these models; the times in the table are rough calculations from the fuel consumption at full load, not guarantees.

Choose the MHD40 when your load approaches 30–32 kW and you want the heated fuel unit. If 30 kW is enough, the MHD30 is lighter (720 kg) and smaller but has no heated unit; if you need 50 kW and a 120 l tank, look at the MHD50.

How much fuel does the MHD40 use, and how long does it run on a full tank?

The manufacturer states fuel consumption below 205 g/kWh and up to 8 h of continuous running on a 70 l tank. It does not say what load that figure applies to.

A rough calculation at the full 40 kW load: 205 g/kWh × 40 kW = 8.2 kg of diesel per hour, or about 9.8 l/h (diesel density 0.84 kg/l). On that basis a 70 l tank lasts about 7.2 h at full rated power, which is shorter than the manufacturer’s 8 h. If the generator will run close to full power, plan your fuel for 7.2 h; this is an indicative figure, not a guaranteed one. At a lower load it uses less fuel. If you need longer running without refuelling, an auxiliary fuel tank is available as an option.

How does a generator with ATS work with a hybrid inverter?

The MHD40 has a built-in ATS and a factory-fitted Two-Wire Switch connection with a voltage-free contact, so the generator can start and stop by itself without anyone having to step in.

• On a site without solar panels, the ATS watches the grid: when the voltage drops it starts the generator and switches the site over, and when the grid returns it stops the engine and switches back to grid power.
• With a hybrid or off-grid inverter, the generator connects to the inverter’s generator input, and the inverter decides when it needs extra energy.
• When the battery is flat, the inverter sends a signal to the Two-Wire Switch connection and the generator takes over the loads and charges the batteries.

Closing the contact starts the generator; opening it shuts the engine down safely. The manufacturer states compatibility with Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters. Connecting the generator to the building’s wiring and configuring the ATS must be done by a certified electrician.

How do you connect a backup generator to a house or business?

A generator is connected to the building’s internal network through a permanent connection. This model already has the ATS built in, so the changeover between grid and generator is automatic and no separate ATS unit is needed. 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

The same ESO page advises choosing the power according to your connection capacity, and, when connecting single-phase loads to a three-phase generator, checking the single-phase limit, because the datasheet gives the total power of all three phases.

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

How do you split the load across phases, and what should you know before buying?

The MHD40 supplies three-phase 230 V / 400 V and powers both three-phase and single-phase loads. It does not deliver its full power on a single phase, so spread single-phase loads as evenly as possible across all three phases and avoid large imbalance.

When calculating the load, allow for starting currents: inductive loads such as pumps or compressors draw 2–5 times more current at start-up than when running. Running at 100 % power for long periods is not recommended. The optimal load for engine and alternator life is 75–80 % of rated power, which for the MHD40 is about 30–32 kW. In a system with storage, add the power the generator will use to charge the batteries to the building’s demand.

The manufacturer states a noise level of 72 dB, so it is worth planning the position in advance if the generator will stand near homes. It weighs 850 kg and measures 2400 × 1000 × 1300 mm, so unloading and moving it takes certified straps or lifting equipment of suitable capacity. The ATS is built in, so you do not need to buy a separate changeover unit. The fuel is diesel. A heated fuel block makes cold starts easier, and an auxiliary fuel pump is fitted at the factory.

Frequently asked questions

How long does the Marsun MHD40 run on a full tank?

The manufacturer states up to 8 h of continuous running on the 70 l tank. At the full 40 kW load, a rough calculation from 205 g/kWh gives about 7.2 h, so if you run near full power, plan for that figure.

How much fuel does the MHD40 use?

The MHD40 uses no more than 205 g/kWh; at the full 40 kW load that is about 9.8 l of diesel per hour. At a lower load consumption is lower.

Does the Marsun MHD40 have a built-in ATS?

Yes, the MHD40 has a factory-fitted ATS. When the grid voltage drops it starts the generator and switches the power over, and when the grid returns it shuts the generator down.

Which hybrid inverters is the MHD40 compatible with?

The manufacturer states Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters; the inverter controls automatic starting through the Two-Wire Switch connection. Hybrid Energy matches the exact wiring to your system.

Can a generator be connected straight to the house fuse board?

No. According to ESO, only through a permanent connection with measures that stop voltage reaching the ESO grid, and only by qualified specialists. On the MHD40 the changeover is done by the built-in ATS.

Is a 40 kW diesel generator suitable for a home, farm or building site?

Yes, the MHD40 is intended for backup power for homes and farms, building sites, solar PV systems with storage and off-grid systems. Hybrid Energy delivers anywhere in Lithuania, installs and commissions it.

How loud is the MHD40?

The manufacturer states a noise level of 72 dB, so it is worth planning the position in advance if the generator will stand near homes.

Can I connect single-phase appliances to the MHD40?

Yes, 230 V single-phase loads can be connected, but the model does not deliver the full 40 kW on a single phase, so single-phase loads need to be spread evenly across the three phases.

What is the optimal load for the MHD40?

For long running, 75–80 % of rated power is optimal, which is about 30–32 kW. Hybrid Energy helps you work out the real load of your site, including starting currents.

How much does the MHD40 weigh?

The generator weighs 850 kg and measures 2400 × 1000 × 1300 mm, so unloading and moving it takes lifting equipment or certified straps.

Sources

• Marsun MHD40 manufacturer datasheet (PDF), checked 2026-10-26
• ESO — Recommendations for installing a backup source, checked 2026-10-26