Marsun MHD25W 25 kW Diesel Generator with Built-in ATS

The Marsun MHD25W is a three-phase 25 kW (26 kW maximum) liquid-cooled diesel generator with built-in ATS and Modbus monitoring. Compared with the MHD25 it has a different engine (WP2.3D33E200, 2300 cm³ vs 2500 cm³), a smaller 60 l tank instead of 70 l, 11 l of oil instead of 9.5 l and a higher weight of 700 kg (the MHD25 weighs 680 kg). The manufacturer states up to 8 h of continuous running; a calculation from 205 g/kWh at full power gives about 9.8 h for the 60 l tank, against about 11.5 h for the MHD25’s 70 l.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MHD25W differs from the MHD20, MHD20H and MHD25

Choose the MHD25W when you need a 25 kW-class generator and a 60 l tank is enough (up to 8 h by the manufacturer, about 9.8 h theoretically at full power). If you want the 70 l tank (about 11.5 h theoretically), 27 kW maximum power and 20 kg less weight, take the MHD25. If the long-term load stays within 15–16 kW, the 20 kW-class MHD20 is enough, and only the MHD20H has a heated fuel block.

How much fuel does the MHD25W use and how long does it run on a full tank?

According to the manufacturer, the Marsun MHD25W with its 60 l tank runs continuously for up to 8 hours. Use that figure when planning backup power.

A rough calculation from the specific consumption: 205 g/kWh × 25 kW is about 5.1 kg of diesel per hour, or roughly 6.1 l/h (diesel density 0.84 kg/l). By that formula a 60 l tank would last about 9.8 hours at full rated power. That is a theoretical upper limit, not a guaranteed run time: the manufacturer gives consumption as “less than 205 g/kWh”, and real consumption depends on load, temperature and engine condition.

Diesel generator with ATS: automatic start from a hybrid inverter

The MHD25W has a built-in ATS and a factory Two-Wire Switch dry-contact connector, so it can start and stop on its own without anyone present. There are two typical setups:

• 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 reconnects the grid.
• With a hybrid or off-grid inverter. The generator is connected to the inverter’s generator input. When the battery runs flat, the inverter sends a signal to the Two-Wire Switch connector and the generator takes over the load and charges the batteries.

Closing the contact starts the engine; 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 to connect a backup generator to a house

A generator is connected to the site’s internal network through a fixed connection. The MHD25W already has the ATS built in, so switching 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

ESO also 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.

3-phase diesel generator: how to spread the load across phases

The MHD25W powers both three-phase 400 V and single-phase 230 V loads, but it does not deliver full power on a single phase. Spread single-phase appliances as evenly as possible across all three phases and avoid large imbalance.

• Starting currents. Inductive loads such as pumps and compressors draw 2–5 times more current when starting than when running.
• Optimal load. Running at 100 % for long periods is not recommended. The recommended range for the engine and alternator is 75–80 % of rated power, for the MHD25W about 18.8–20 kW (25 % reserve).
• With battery storage. Add the power the generator will use to charge the batteries to the building’s demand.

Frequently asked questions

How long does the MHD25W run on a full tank?

According to the manufacturer, the Marsun MHD25W with its 60 l tank runs continuously for up to 8 hours. A theoretical calculation from 205 g/kWh at the full 25 kW gives about 9.8 hours, but plan around the manufacturer’s figure.

How much fuel does a 25 kW diesel generator like the MHD25W use?

The Marsun MHD25W has a specific consumption of less than 205 g/kWh, so at the full 25 kW it uses about 5.1 kg, or 6.1 l, of diesel per hour. At lower load consumption is lower.

Is the MHD25W a generator with ATS?

Yes. The Marsun MHD25W has a factory-fitted ATS: when the grid voltage drops it starts the generator and switches the supply, and when the grid returns it shuts the generator down.

Which inverters is the MHD25W compatible with?

The manufacturer states that the Marsun MHD25W is compatible with Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters. The start signal is passed through the Two-Wire Switch connector.

Can I connect the generator straight to my house’s distribution board?

No. The MHD25W must be connected to the building’s network only through a fixed connection with measures that stop voltage from reaching ESO’s networks, and only by qualified specialists. Hybrid Energy does this for you: we deliver anywhere in Lithuania, install and connect it.

Is the MHD25W suitable for a house, a farm or a building site?

Yes. The 25 kW Marsun MHD25W is made for backup power for homes and farms, building sites, solar systems with batteries and off-grid setups. Hybrid Energy helps you work out whether this power is enough for your site.

How loud is the MHD25W?

The manufacturer states a noise level of 72 dB for the Marsun MHD25W. Near homes, choose the generator’s location with the neighbours in mind.

Can I connect single-phase appliances to the MHD25W?

Yes. The MHD25W supplies 230 V single-phase as well, but you will not get the full 25 kW on one phase. Single-phase loads should be spread evenly across the three phases.

What is the optimal load for the MHD25W?

The optimal load for the Marsun MHD25W is 75–80 % of rated power, which is about 18.8–20 kW. Running at 100 % for long periods is not recommended.

How does the MHD25W differ from the MHD25?

Both Marsun models are 25 kW three-phase diesel generators with built-in ATS and Modbus. The MHD25W has a WP2.3D33E200 engine (2300 cm³), 26 kW maximum power, a 60 l tank and weighs 700 kg. The MHD25 has a YCV2.5T45-G20 engine (2500 cm³), 27 kW maximum power, a 70 l tank and weighs 680 kg.

Sources

• Marsun MHD25W manufacturer datasheet (PDF), checked 2026-10-26
• ESO — Recommendations for installing a backup power source, checked 2026-10-26