Marstek MARS I PLUS 5.12kWh battery module (MST-MARS I PLUS-5.0KBAT)5.12kWh stackable LFP battery module with V-Boost for MARS I PLUS inverters

Overview

MST-MARS I PLUS-5.0KBAT is the battery module of the Marstek MARS I PLUS system. It stores 5.12kWh in 32 LFP cells of 50Ah, of which 5kWh is usable, and charges or discharges at up to 5kW. Its V-Boost stage presents 800V nominal to the three-phase inverters and 400V nominal to the single-phase models. One to six modules stack under one inverter for 5.12–30.72kWh, and four systems in parallel reach 122.88kWh. Each module measures 628×390×194mm, weighs 63kg and is rated IP65.

• Three-phase 8, 10 and 12kW; single-phase 3.6 to 6kW
• One to six 5.12kWh LFP modules per inverter
• Up to four systems in parallel: 48kW and 122.88kWh
• Backup switchover under 10ms, generator input
• SG-Ready heat pump control, optional EV charger with V2X
• IP65, natural cooling, below 30dB, 10-year warranty

How it works

MARS I PLUS combines PV trackers, a battery converter, on-grid and backup outputs and a local energy manager in one inverter, with battery modules stacked in a column beneath it. Each 5.12kWh module holds 32 LFP cells of 50Ah. Its V-Boost stage raises the module output to 800V nominal (650–950V) for the three-phase inverters and to 400V nominal (350–550V) for the single-phase ones, and Marstek balances the cells in real time so that a weaker module does not limit the stack.

Three-phase models have four trackers with one string each, a 200–850V MPPT range and 1,000V maximum input; single-phase models have two trackers and accept up to 550V. With a Marstek CT002 or a Shelly meter on the main panel the system avoids export to the grid, and the AI mode plans charging around time-of-use or dynamic prices. If the grid fails, the backup output takes over within 10ms.

Key features

Beyond PV and storage, the inverter manages loads that usually need separate controllers. An SG-Ready contact or RS-485 link steers a heat pump towards solar surplus. On three-phase systems the optional Marstek EV DC/AC charger adds up to 25kW DC charging and 12kW bidirectional V2X power; single-phase systems support a 7kW AC charger. A generator input supports a diesel generator in off-grid operation.

Capacity is set per inverter from one to six modules (5.12–30.72kWh). Up to four complete systems can run in parallel through the two parallel CAN ports, giving up to 48kW and 122.88kWh. On the 12kW three-phase model the backup output delivers 12kW nominal and 12.6kVA apparent power, with 150–200% peak current for 1s.

Installation and compatibility

The three-phase inverter measures 628×195×498mm and weighs 55kg; the single-phase version is 628×195×398mm and 35kg. Each battery module is 628×390×194mm and 63kg, so a full stack of six modules adds 378kg. The inverters are IP65 with natural cooling, rated for -25…+60°C and up to 4,000m with derating above 2,000m; the battery modules are also IP65 and naturally cooled.

The three-phase datasheet lists EN 50549-1:2019 and VDE-AR-N 4105:2018 as grid standards; the single-phase datasheet adds VDE 0126-1-1, EN 50438 and CEI 0-21. Battery modules carry IEC/EN 62619, IEC/EN 63056, UL 1973, UL 9540A and UN38.3. Marstek notes on its product page that design details may still change before series delivery.

Monitoring and settings

A 10.1in touchscreen on the inverter gives local access to live data, guided setup and the built-in EMS. Remote monitoring runs in the Marstek app over Wi-Fi or Bluetooth, and Ethernet is available for a wired connection. Separate RS-485 ports serve the meter, the heat pump and an external EMS, and Marstek publishes an open API for third-party energy management. Four digital inputs, two digital outputs and three CT inputs complete the interface.

Questions and answers