Marsun MHD50S 50 kW Three-Phase Diesel Generator with ATS

The Marsun MHD50S is a 50 kW (55 kW maximum) three-phase diesel generator with a built-in ATS and an 80 l tank. Compared with the MHD50 of the same power it has a 4.1 l (4100 cm³) engine, an 80 l tank instead of 120 l, a mass of 1100 kg and slightly lower consumption (below 202 g/kWh instead of below 205 g/kWh), but no heated fuel unit; the manufacturer’s data lists no auxiliary fuel pump or tank. The manufacturer states up to 8 h of running, yet the rough calculation for the full 50 kW load gives only about 6.7 h, so for longer running without refuelling the MHD50 is the more reliable choice.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MHD50S differs from the MHD50 and MHD40

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 MHD50S when you need 50 kW and neither the 120 l tank nor the heated fuel unit is essential. If longer running without refuelling and a heated unit matter, take the MHD50; if 40 kW is enough, look at the MHD40.

How much fuel does the MHD50S use and how long does it run on a full tank?

The manufacturer states fuel consumption below 202 g/kWh and up to 8 hours of continuous running on the 80 l tank. The datasheet does not say at what load that figure applies.

A rough calculation for a full 50 kW load: 202 g/kWh × 50 kW = 10.1 kg of diesel per hour, or about 12 l/h (diesel density 0.84 kg/l). On that basis the 80 l tank lasts about 6.7 hours at full rated power, which is less than the manufacturer’s 8 hours. If the generator will run close to full load, plan your fuel on 6.7 hours; this is an estimate, not a guaranteed figure. At a lower load it burns less fuel.

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

The MHD50S has a built-in ATS and a factory Two-Wire Switch connection with a dry (voltage-free) contact, so the generator can start and stop on its own.

• On a site without solar, 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 is wired to the inverter’s generator input and the inverter decides when it needs extra energy.
• When the battery is depleted, 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?

A generator is connected to the building’s internal wiring through a fixed connection. The ATS is already built into this model, so switching between the grid and the generator is automatic and no separate transfer device 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

On the same page ESO advises choosing the power according to your connection capacity and, when connecting single-phase loads to a three-phase generator, taking the single-phase limit into account, because the datasheet gives the combined 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 to spread the load across phases

The MHD50S supplies three-phase 230 V / 400 V and powers both three-phase and single-phase loads. It does not provide full power on a single phase, so spread single-phase loads as evenly as possible across all three phases and avoid a large imbalance.

When sizing the load, allow for starting currents: inductive loads such as pumps and compressors draw 2 to 5 times more current at start-up than when running. Running at 100% power for a long time is not recommended. The optimum for engine and alternator life is 75 to 80% of rated power, which for the MHD50S is about 37.5 to 40 kW. In a system with energy storage, add the power the generator will use to charge the batteries to the building’s demand.

What to know before buying

The manufacturer states a noise level of 74 dB measured at 7 m, so think about where to place it if it will stand near homes. The generator weighs 1100 kg and measures 2400 × 1000 × 1300 mm; unloading and moving it takes certified straps or lifting equipment of suitable capacity. The ATS is built in. The fuel is diesel, and the model has no heated fuel block, so if it will stand outdoors in winter, discuss that before you buy.

Frequently asked questions

How long does the Marsun MHD50S run on a full tank?

The manufacturer states up to 8 hours of continuous running on the 80 l tank. At a full 50 kW load, a calculation from 202 g/kWh gives about 6.7 hours, so plan on that figure if it will run at full power.

How much fuel does the MHD50S use?

The MHD50S uses no more than 202 g/kWh: at a full 50 kW load that is about 12 l of diesel per hour. At a lower load consumption is lower.

Does the Marsun MHD50S have a built-in ATS?

Yes. The MHD50S has a factory-fitted ATS that starts the generator and switches the supply when the grid fails, and stops it when the grid returns.

Which hybrid inverters is the MHD50S compatible with?

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

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

No. According to ESO, only through a fixed connection with measures that stop voltage reaching the ESO grid, and only by qualified specialists. On the MHD50S the switching is done by the built-in ATS.

Is a 50 kW diesel generator suitable for a house, a farm and a construction site?

Yes, the MHD50S is intended for backup power for homes and farms, construction sites, solar PV systems with storage and off-grid systems. Hybrid Energy delivers anywhere in Lithuania and installs and commissions it.

How loud is the MHD50S?

The manufacturer states 74 dB at a distance of 7 m, so it is worth choosing the position carefully if it will stand near homes.

Can single-phase appliances be connected to the MHD50S?

Yes, 230 V single-phase loads can be connected, but the model does not give full 50 kW on one phase, so single-phase load must be spread evenly across the three phases.

What load is recommended for the MHD50S?

For long running, 75 to 80% of rated power is optimal, about 37.5 to 40 kW. Hybrid Energy helps calculate the real load of your site including starting currents.

How much does the MHD50S weigh?

It weighs 1100 kg and measures 2400 × 1000 × 1300 mm, so unloading and moving it needs lifting equipment or certified straps.

Sources

• Marsun MHD50S manufacturer datasheet (PDF), checked 2026-10-26
• ESO, recommendations for installing a backup source, checked 2026-10-26