Victron home backup kit 3.55kWh – MultiPlus-II 48/5000/70-50 with Pylontech US3000C, single-phase5kVA 48V single-phase backup kit with 3.55kWh LiFePO4 battery and GX monitoring

Overview

This kit pairs a Victron MultiPlus-II 48/5000/70-50 inverter/charger with one Pylontech US3000C LiFePO4 module of 3.55kWh. Two versions are offered: the MultiPlus-II 48/5000/70-50 GX with built-in GX device and display, or the standard MultiPlus-II with a separate Cerbo GX MK2 and GX Touch 50 screen. The inverter delivers 4000W continuous and 9000W peak, charges at up to 70A and passes up to 50A from the grid. One US3000C is rated 37A recommended, so for loads near 4kW Victron's sizing guide calls for more modules.

• MultiPlus-II 48/3000 or 48/5000, 230V single-phase
• Pylontech US3000C or Pytes V5°α LiFePO4 modules
• Battery BMS talks to the GX device over CAN
• Switch to battery in under 20ms on grid failure
• Battery expandable with modules of the same series
• VRM remote monitoring through the GX device

What's in the kit

• 1 × Victron Energy MultiPlus-II 48/5000/70-50 GX version with integrated GX
• 1 × Victron Energy MultiPlus-II 48/5000/70-50 version with Cerbo GX
• 1 × Victron Energy Cerbo GX MK2 version with Cerbo GX
• 1 × Victron Energy GX Touch 50 version with Cerbo GX
• 1 × Pylontech US3000C
• 1 × Battery communication cable

How the kits work

The MultiPlus-II is an inverter, battery charger and transfer switch in one case. With grid present it passes power to the loads and charges the battery; when the grid fails it takes over from the battery in less than 20ms, so computers and other electronics keep running. PowerControl and PowerAssist cap the current drawn from a weak supply or generator and add battery power when loads exceed that limit. The same unit can run as an ESS for self-consumption when the installation and grid connection allow it.

The battery's BMS reports charge and discharge limits, alarms and state of charge to the GX device over CAN, and with DVCC enabled the GX passes those limits to the MultiPlus-II. Victron's integration guides require a GX device for both brands: Pylontech US3000C connects with Victron's VE.Can to CAN-bus BMS Type A cable, Pytes batteries through the BMS-Can or VE.Can port, with DVCC on and SVS and STS off.

Sizing the battery

Victron's Pylontech guide sets minimum module counts so the battery can supply the inverter's inrush and continuous current. Its example, based on 25A modules, lists two modules for a MultiPlus 48/3000 and four for a 48/5000. A US3000C is rated 37A recommended, about 1.8kW at 48V, so a single module limits continuous battery power well below the inverter's 4000W; more modules of the series can be added. A Pytes V5°α supplies 75A recommended and 100A maximum at 51.2V.

Installation and what to add

Pylontech US modules are IP20 units for a dry indoor room at 0–50°C; Pytes specifies charging between 0°C and 45°C. The MultiPlus-II must never sit directly above the battery, whose gases would damage it. The installer adds the DC fuse or breaker, battery cables cut to length where not supplied, AC protection and earthing, and the configuration in VEConfigure or VictronConnect. For grid-parallel ESS use, check national rules; Victron publishes EN 50549-1 and VDE-AR-N 4105 certificates for the 3kVA and 5kVA MultiPlus-II.

Questions and answers