Two Victron MPPTs on One Battery: VE.Smart Networking

Running two Victron MPPTs on one battery bank is common when you have panels on two roof faces, or more solar than one controller can take. Victron’s VE.Smart Networking makes the two SmartSolars charge as if they were one big charger. Here’s the wiring and setup, based on Victron’s MPPT and VE.Smart Networking manuals.

Electrical work can be dangerous: follow the manual, fuse and size every cable correctly, and use a licensed electrician for anything connected to household wiring.

A two-MPPT setup video.

Wiring Two Victron MPPTs on One Battery

Each MPPT gets its own array. Never connect two controllers’ PV inputs together.
Each MPPT gets its own fused battery cable to the bus bar or battery.
Use the same battery settings on both.
Mount them with clearance. Victron asks for at least 10cm above and below each unit.

Why Synchronise?

Unsynchronised controllers each run their own charge cycle. One may drop to float while the other is still in absorption, or each may decide absorption differently. Victron says synchronised charging “improves the charge efficiency and battery life”.

How Synchronised Charging Works

From Victron’s VE.Smart Networking manual:

The chargers elect a master, which sets the charge state and voltage. All units switch from bulk to absorption at the same time.
Each unit still controls its own current. There’s no network-wide maximum charge current. If you need one, for example with east and west arrays on a small battery, use a GX device with DVCC.
You can’t choose the master, so all chargers must have identical battery settings.
Without a battery monitor, the chargers combine their output currents to estimate battery current for the tail-current setting.

Setup Steps

If you have a SmartShunt, BMV or Smart Battery Sense, set it up first: in VictronConnect, go to Settings, VE.Smart Networking, Create Network.
On each SmartSolar, go to Settings, VE.Smart Networking, Join Existing, and pick the network.
Check the network icon on each charger’s main page. The LED blinks every 4 seconds when it’s receiving data.

Limits to Know

Up to 10 devices per network.
Only one battery sensor per network. Every sensor and charger must be on the same battery.
Some older SmartSolar 150/85, 150/100, 250/85 and 250/100 part numbers lack the hardware. A VE.Direct Bluetooth Smart dongle works around it.
If chargers are already synchronised over VE.Can, or controlled by a GX device in ESS or by a managed battery, VE.Smart pairing is ignored or unnecessary.
The Orion XS can share sensor data but doesn’t take part in synchronised charging.

Victron lists every SmartSolar 100/30 & 100/50 variant, with datasheets, on its official product page.

Worked Example: East and West Roof Arrays

A van with 200W on the east side of the roof and 200W on the west, both on a 12V lithium battery:

MPPT 1 (east): SmartSolar 100/20, peaks in the morning.
MPPT 2 (west): SmartSolar 100/20, peaks in the afternoon.
Battery sensor: SmartShunt, creating the VE.Smart network.

In the morning, MPPT 1 does most of the charging; by afternoon, MPPT 2 takes over. Synchronised, both switch to absorption together and share one tail-current decision based on the SmartShunt’s real battery current. Combined, the two arrays spread charging over more of the day than a single flat array would.

Worked Example: Adding Solar Beyond One Controller

A cabin with a SmartSolar 100/50 on 700W of panels at 12V wants to add another 600W. Rather than replace the controller, add a second SmartSolar 100/50 on the new array. The combined maximum charge current is 100A, so check the battery’s recommended charge rate. For a 400Ah LiFePO4 battery, 100A is often within the maker’s limits (check your datasheet). If you need to cap the total, a GX device with DVCC can set a system-wide limit.

Battery Settings to Match on Every Charger

Setting	Why it must match
Absorption voltage	The master sets it, so every unit must use the same value
Float voltage	Same reason
Absorption time and tail current	So the network ends absorption consistently
Temperature compensation	Shared from the sensor; same coefficient on each unit
Low-temperature cut-off	So no charger keeps charging in the cold

The quickest way is to save a user-defined battery preset on one charger and load it on the others in VictronConnect.

Cable and Fuse Sizing for Two Controllers

Each MPPT’s battery cable is sized and fused for that controller’s maximum current. For two 100/50s on 12V, that’s two 50A circuits, each with a fuse close to the busbar or battery. Running both to a common busbar keeps the cable lengths similar, which helps both controllers see the same battery voltage.

Checking the Network Is Working

Network icon: shown on each charger’s main page in VictronConnect.
Charge state: all units should show the same state (bulk, absorption or float) at the same time.
Battery voltage: each charger should show the sensor’s voltage reading, not just its own terminal voltage.

If one charger shows a different state, check it has joined the same network and has identical battery settings.

When to Move to a GX Device

VE.Smart Networking is ideal for small systems. A Cerbo GX becomes useful when you want a single dashboard, VRM remote monitoring, a system-wide charge current limit through DVCC, or integration with a managed lithium battery or inverter-charger. Both MPPTs connect to the GX by VE.Direct cables, and the GX then coordinates them.

FAQ

Can I mix a 100/30 and a 100/50?

Yes. Each limits its own current. Keep battery settings identical.

Do I need a Cerbo GX?

No. VE.Smart Networking is designed for small systems without one.

Can a BlueSolar join?

Only with a VE.Direct Bluetooth Smart dongle.

Can three or more MPPTs share one battery?

Yes. A VE.Smart network supports up to 10 devices, all synchronised by the elected master.

Do both MPPTs need the same panel wattage?

No. Each controller works with its own array and limits its own current, so arrays can differ in size and orientation.

Sources: Victron VE.Smart Networking manual; MPPT solar charger manual (victronenergy.com, accessed Oct 2026).