How to Choose a Victron Solar Charge Controller

Victron solar charge controllers all use MPPT tracking and share one naming rule: the first number is the maximum panel open-circuit voltage, the second is the maximum charge current. A 100/30 accepts up to 100V from the panels and charges at up to 30A. Once you know that, choosing one comes down to your array’s voltage, its wattage and your battery voltage.

Victron Energy explains how its MPPT controllers work.

Victron Solar Charge Controllers: Popular Models

Model	Max PV Voc	Charge current	Nominal PV at 12V	Nominal PV at 24V	Load output
SmartSolar 75/15	75V	15A	220W	440W	Yes
SmartSolar 100/20	100V	20A	290W	580W	Yes
SmartSolar 100/30	100V	30A	440W	880W	No
SmartSolar 100/50	100V	50A	700W	1,400W	No
SmartSolar 150/35	150V	35A	500W	1,000W	No

Sources: Victron SmartSolar MPPT 75/10–100/20, 100/30 & 100/50 and 150/35 & 150/45 datasheets. The 150/35 also supports 36V and 48V batteries (2,000W at 48V).

SmartSolar vs BlueSolar

SmartSolar has Bluetooth built in, so you set it up and watch harvest history in the free VictronConnect app. BlueSolar has no Bluetooth; you add the VE.Direct Bluetooth Smart dongle to get the same app access. Both have a VE.Direct port for a Cerbo GX and VRM. SmartSolar can also take battery voltage and temperature wirelessly from a Smart Battery Sense or BMV-712.

How to Pick the Right Size

Voltage first. Add up the open-circuit voltage of panels in series, then allow for cold weather, which raises Voc. Victron’s online MPPT calculator does this with local temperatures. Never exceed the first number.
Current second. Divide array watts by battery voltage for a rough charge current: 400W ÷ 12V ≈ 33A (estimate), which points to a 100/50 rather than a 100/30.
Oversizing. Victron’s nominal PV figures are guidance. More panel wattage simply gets clipped at the controller’s rated current.

Which One for Which Build

One or two small panels on a trailer or shed: 75/15 or 100/20, which also have a load output for lights.
Typical van with 200–400W: 100/30 or 100/50.
Panels wired in series for long cable runs, or a 24V/48V bank: 150/35 or larger.
Cabins with big arrays: 250V-class models such as the 250/100.

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Buy: Victron SmartSolar MPPT 100/30 on Amazon

For the complete spec sheet and current manual, see the Victron SmartSolar 100/30 & 100/50 page.

Worked Example: A Weekend Trailer With One Panel

A small travel trailer with one 100W panel and a 12V 50Ah battery:

A 100W panel at 12V gives about 8A at most, so the SmartSolar 75/15 fits with headroom (estimate).
Its load output can switch the trailer’s LED lights off at low battery voltage.
A panel with around 22V Voc sits far below the 75V limit, even on a cold morning (estimate).

Worked Example: A Van With 400W on the Roof

A van with two 200W panels and a 12V 200Ah lithium battery:

Wired in parallel: about 23V Voc, but around 22A of combined current. Fine for a 100/30 or 100/50.
Wired in series: about 46V Voc, and roughly 11A. Thinner roof cable, and still well under 100V in the cold (estimate).
400W ÷ 12V ≈ 33A, so a 100/50 harvests the full array, while a 100/30 clips the peak at 30A (estimate).

Worked Example: The Same Array on 24V

Moving that 400W array to a 24V battery halves the charge current to about 17A, so a 100/20, rated 580W at 24V, can handle it (estimate). Higher battery voltage lets a smaller controller do the same job.

Worked Example: A Cabin With Three Panels in Series

A cabin with three 300W panels at about 40V Voc each, wired in series:

Total Voc is about 120V, rising in cold weather, so a 150V controller like the 150/35 is the right class (estimate).
900W at 24V is roughly 38A, slightly over the 150/35’s 35A rating, so it clips a little at peak sun, which is harmless. On a 48V bank, the same array charges at about 19A (estimate).

Setup Steps

Connect the battery to the controller first, with a fuse at the battery.
Let it detect battery voltage, or set it in VictronConnect.
Connect the panels, ideally through a PV isolator.
Choose the battery preset or set the maker’s voltages.
Check the history tab after a few days to see daily yield and time in bulk, absorption and float.

Running More Than One Controller

Separate controllers can each run their own array, for example one for the roof and one for a portable ground panel. On a VE.Smart network, they share battery voltage and temperature, and with a GX device they share DVCC limits from a managed battery.

Reading the Name in Practice

Model	Panels it suits (estimate)
—	—
75/15	One 100–200W panel on 12V
100/20	Up to about 290W on 12V or 580W on 24V
100/30	Up to about 440W on 12V
100/50	Up to about 700W on 12V
150/35	Series strings up to 150V, about 1,000W on 24V

Based on Victron’s nominal PV figures. Your panel voltages and cold-weather Voc decide the series limit.

Mounting and Cooling

Mount the controller vertically close to the battery, with space above and below for airflow. Short, thick battery cables reduce voltage drop, so the controller reads battery voltage accurately. For longer cables, a Smart Battery Sense sends the true battery voltage over Bluetooth.

FAQ

Can two Victron MPPTs charge one battery?

Yes. Each controller runs its own array; with a GX device they can share settings and battery data.

Is BlueSolar any less efficient?

The tracking hardware is the same family. The difference is Bluetooth and Smart networking.

Do Victron controllers work with LiFePO4?

Yes. Built-in presets and a fully adjustable profile in VictronConnect.

What does the load output do?

On the 75/15 and 100/20, it powers small DC loads directly and switches them off at a set low battery voltage.

Do I need a GX device?

No. A SmartSolar works alone with VictronConnect. A GX device adds VRM remote monitoring and system coordination.

What size fuse goes between the controller and the battery?

Check the controller’s manual. It lists a fuse and cable size for each model’s charge current.

Sources: Victron SmartSolar and BlueSolar charge controller datasheets and overview (victronenergy.com, accessed Oct 2026); Victron Energy, “How does a Victron Energy MPPT Solar Charge Controller work?”.