Marsun MHD25 25 kW Three-Phase Diesel Generator with ATS

The Marsun MHD25 is the core 25 kW model of the series: a three-phase (230 V / 400 V) liquid-cooled diesel generator with 27 kW maximum power, built-in ATS and a 70 l tank. It has 5 kW more rated power than the MHD20 and MHD20H, and compared with the MHD25W it has a larger engine (2500 vs 2300 cm³), a tank 10 l larger and a weight 20 kg lower (680 vs 700 kg). Choose it when the long-term load is about 18.8–20 kW (75–80 % of rated power); the manufacturer states up to 8 h of continuous running on a full tank.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MHD25 differs from the MHD20, MHD20H and MHD25W

Choose the MHD25 if you need a 25 kW-class generator with the highest maximum power of these four models, 27 kW, and a 70 l tank. If the recommended long-term load (75–80 % of power) stays within 15–16 kW, the MHD20 is enough, and if the engine has to start in the cold, the MHD20H adds a heated fuel block. The MHD25W is worth considering when a different engine (2300 cm³) and a 60 l tank suit you; the MHD25 has the larger tank and weighs 20 kg less.

How much fuel does the MHD25 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. Use this manufacturer figure when planning your fuel supply.

A rough calculation at the full 25 kW load: 205 g/kWh × 25 kW = 5.1 kg of diesel per hour, or about 6.1 l/h (diesel density 0.84 kg/l). On that basis a 70 l tank would last about 11.5 h, but that is only a theoretical figure and is longer than the manufacturer’s, so rely on the manufacturer’s number. 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 MHD25 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 MHD25 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 MHD25 is about 18.8–20 kW. In a system with storage, add the power the generator will use to charge the batteries to the building’s demand.

The fuel is diesel. An auxiliary fuel pump is fitted at the factory, an auxiliary fuel tank is optional, and this model has no heated fuel block.

The generator and connected equipment are protected by no-load protection, automatic voltage regulation (AVR), an overcurrent breaker, overpressure protection and automatic shutdown when 10 % of the fuel is left. A panel shows voltage and frequency, and operating parameters can be monitored remotely over Modbus.

Frequently asked questions

How long does the Marsun MHD25 run on a full tank?

The manufacturer states up to 8 h of continuous running on the 70 l tank. A rough calculation from 205 g/kWh at the full 25 kW load gives about 11.5 h, but plan around the manufacturer’s figure.

How much fuel does the MHD25 use?

The MHD25 uses no more than 205 g/kWh; at the full 25 kW load that is about 6.1 l of diesel per hour. At a lower load consumption is lower.

Does the Marsun MHD25 have a built-in ATS?

Yes, the MHD25 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 MHD25 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 MHD25 the changeover is done by the built-in ATS.

Is a 25 kW diesel generator suitable for a home, farm or building site?

Yes, the MHD25 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 MHD25?

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 MHD25?

Yes, 230 V single-phase loads can be connected, but the model does not deliver the full 25 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 MHD25?

For long running, 75–80 % of rated power is optimal, which is about 18.8–20 kW. Hybrid Energy helps you work out the real load of your site, including starting currents.

How much does the MHD25 weigh?

The generator weighs 680 kg and measures 2000 × 900 × 1200 mm, so unloading and moving it takes lifting equipment or certified straps.

Sources

• Marsun MHD25 manufacturer datasheet (PDF), checked 2026-10-26
• ESO — Recommendations for installing a backup source, checked 2026-10-26