Marsun MHD25H 25 kW Diesel Generator with ATS and Heated Fuel Unit

The Marsun MHD25H is a 25 kW (27 kW maximum) three-phase diesel generator with a built-in ATS and a heated fuel unit, meant for sites that realistically need up to about 18.8–20 kW (75–80 % of rated power). Of the MHD25H, MHD30, MHD40, MHD50 and MHD50S it is the lightest (680 kg) and it shares its 2000 × 900 × 1200 mm dimensions with the MHD30, while the heated fuel unit, which helps cold starts, is something the 30 kW MHD30 does not have. The manufacturer states a 70 l tank and up to 8 h of running, and the Two-Wire Switch connection lets a hybrid inverter start the generator, so it suits backup power for a house or farm and solar systems with batteries.

Technical specifications

Download the manufacturer datasheet (PDF)

How the MHD25H differs from the MHD30 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 MHD25H if your real load stays within about 18.8–20 kW and a heated fuel unit matters for cold starts. If you need more power in the same dimensions, look at the MHD30 (30 kW, but without the heated unit); if you need both more power and the heated unit, the MHD40 (40 kW, 850 kg, larger dimensions) is the next step. Hybrid Energy sizes the model to your actual load.

How much fuel does the MHD25H use and how long does it run on a full tank?

According to the manufacturer, the Marsun MHD25H with its 70 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 70 l tank would last about 11.5 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. The generator shuts off automatically when 10 % of the fuel is left, and an additional fuel tank is available as an option for longer running.

Diesel generator with ATS: automatic start from a hybrid inverter

The MHD25H 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 MHD25H 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 MHD25H 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 MHD25H 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.
• Noise. The manufacturer states 72 dB, so think about placement near homes.
• Weight and handling. 680 kg, 2000 × 900 × 1200 mm. Unload and move it with certified straps or lifting equipment of suitable capacity.

Frequently asked questions

How long does the MHD25H run on a full tank?

According to the manufacturer, the Marsun MHD25H with its 70 l tank runs continuously for up to 8 hours. A theoretical calculation from 205 g/kWh at the full 25 kW gives about 11.5 hours, but plan around the manufacturer’s figure.

How much fuel does a 25 kW diesel generator like the MHD25H use?

The Marsun MHD25H 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 MHD25H a generator with ATS?

Yes. The Marsun MHD25H 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 MHD25H compatible with?

The manufacturer states that the Marsun MHD25H is compatible with Deye, Solis, Solplanet, GoodWe, Victron Energy and Sungrow hybrid inverters. The start signal is passed through the Two-Wire Switch connector. Hybrid Energy matches the exact wiring to your system.

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

No. The MHD25H 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 MHD25H suitable for a house, a farm or a building site?

Yes. The 25 kW Marsun MHD25H 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 MHD25H?

The manufacturer states a noise level of 72 dB for the Marsun MHD25H. Near homes, choose the generator’s location with the neighbours in mind.

Can I connect single-phase appliances to the MHD25H?

Yes. The MHD25H 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 MHD25H?

The optimal load for the Marsun MHD25H is 75–80 % of rated power, which is about 18.8–20 kW. Running at 100 % for long periods is not recommended.

Does the MHD25H have a heated fuel unit?

Yes. The Marsun MHD25H has a heated fuel unit, which makes starting the engine easier at low temperatures.

Sources

• Marsun MHD25H manufacturer datasheet (PDF), checked 2026-10-26
• ESO — Recommendations for installing a backup power source, checked 2026-10-26