Victron SmartSolar MPPT 250/100 and 250/85 Guide

The Victron SmartSolar MPPT 250/100 and its smaller sibling, the 250/85, are Victron’s biggest standard solar charge controllers. They’re built for large arrays wired in long, high-voltage strings. The 250V input lets you put more panels in series, which keeps PV cable thin over long runs. Here’s what they offer, from Victron’s datasheet for the SmartSolar 250/70 up to 250/100.

Victron SmartSolar MPPT 250/100 and 250/85: Specs

	250/85	250/100
Rated charge current	85A	100A
Nominal PV power, 12V	1,200W	1,450W
Nominal PV power, 24V	2,400W	2,900W
Nominal PV power, 36V	3,600W	4,350W
Nominal PV power, 48V	4,900W	5,800W
Max PV short-circuit current	70A (max 30A per MC4 connector)	70A (max 30A per MC4 connector)
Max PV voltage	250V	250V
Max efficiency	99%	99%
Weight	4.5kg	4.5kg

Source: Victron SmartSolar MPPT 250/70 up to 250/100 datasheet (VE.Can version). Check the datasheet for your exact model.

Both detect 12, 24 or 48V batteries automatically, and 36V can be set manually. The battery terminals take 35mm² (AWG2) cable.

Features

Built-in Bluetooth for VictronConnect.
Programmable relay (240V AC/4A, or DC 4A up to 35V and 1A up to 60V) and remote on/off.
Parallel sync: up to 25 units over VE.Can, or up to 10 over Bluetooth.
Tr or MC4 PV connections. MC4 models have two pairs of connectors.
Optional plug-in display.
IP43 electronics, IP22 connection area. Victron rates it from -30°C to +60°C, with full output up to 40°C.

Who It’s For

48V off-grid cabins and homes with 4kW to 6kW of panels on one controller.
Long cable runs from a ground-mount array, where a higher string voltage cuts losses.
Large RV or boat arrays, but at 12V the 250/100 uses only 1,450W of PV, so 24V or 48V is the better match.

Sizing Example

With 48V batteries and 5,800W of panels, the 250/100 runs at its full 100A. Check the cold-weather open-circuit voltage of your strings against the 250V limit, using Victron’s MPPT calculator.

Monitoring

The VE.Direct port (VE.Can on the VE.Can versions) connects to a Cerbo GX for VRM remote monitoring and DVCC, so a CAN-bus lithium battery can set the charge limits. VictronConnect also shows the controller’s daily yield history over Bluetooth.

Good to Know Before You Buy

It’s heavy at 4.5kg. At 12V, most of its PV capacity goes unused. Above 250V, step up to the MPPT RS 450.

You can download the SmartSolar MPPT 250/85 and 250/100 manual and datasheet from Victron Energy’s website.

Worked Example: Designing Strings for a 48V Cabin

A 48V cabin with 15 panels rated around 400W and about 41V open-circuit voltage (Voc):

Five panels in series give roughly 205V Voc at 25°C.
On a -10°C winter morning, Voc rises. With a typical temperature coefficient around -0.28%/°C, that’s about 10% higher, or roughly 225V, still under the 250V limit (estimate).
Six in series would start at about 246V at 25°C and pass 250V in the cold, so five is the safe string length here (estimate).
Three strings of five make 6,000W of panels. The 250/100’s nominal 5,800W at 48V means a little clipping at peak sun, which is normal and harmless (estimate).
Each string’s short-circuit current of around 10.5A adds to about 32A, well within the 70A limit, and split across the two MC4 pairs it stays under 30A per connector (estimate).

Use Victron’s MPPT calculator with your actual panel datasheet and your coldest local temperature before finalising.

Worked Example: Why High Voltage Helps Long Runs

A ground-mount array 30m from the cabin, delivering 6kW:

At about 200V string voltage, current is roughly 30A. Over a 60m round trip in 6mm² copper, the loss is about 5.5V, under 3% (estimate).
At 100V on a 150V controller, the same power needs about 60A, doubling the current and quadrupling the loss in the same cable (estimate).

That’s the main reason to choose a 250V controller for distant arrays.

Worked Example: The 250/85 on 24V

A 24V off-grid workshop with 2,400W of panels suits the 250/85, which lists exactly 2,400W nominal at 24V. At 85A charge current, it puts about 2kW into a 24V bank in full sun (estimate). Moving the same workshop to 48V later would let the 250/85 handle up to 4,900W.

Using the Programmable Relay

The relay can switch an alarm, a vent fan or a generator start signal based on battery voltage or controller state. Victron rates it at 4A up to 35V DC, or 1A up to 60V DC, so a 48V circuit should only drive small loads or a relay coil through it.

Setup Steps

Connect the battery first, using 35mm² (AWG2) cable and the correct fuse.
Let the controller detect 12, 24 or 48V, or set 36V manually.
Connect the PV strings with the PV isolator off, then switch it on.
Pair over Bluetooth in VictronConnect and set the battery charge profile.
Connect VE.Direct or VE.Can to a GX device for VRM and DVCC.

Parallel Controllers

For arrays beyond one controller, add more units. They synchronise over VE.Can (up to 25 units) or Bluetooth (up to 10), so they move through bulk, absorption and float together.

250/100 vs Two Smaller Controllers

One 250/100 keeps the wall tidy and needs one set of battery cables. Two smaller controllers, such as a pair of 150/45 units, split the array into separate inputs, which helps when panels face different directions or sit on different roofs, since each controller tracks its own array. For a single, evenly lit ground-mount array, one large controller is usually the simpler choice.

Cooling and Placement

The 250/100 delivers full output up to 40°C. Mount it vertically with space above and below so air can flow across the heatsink, and keep it out of direct sun. In a hot shed, a small vent fan driven by the programmable relay can help on summer afternoons.

FAQ

What’s the difference between the 250/85 and 250/100?

Charge current (85A vs 100A) and the PV power that goes with it.

Can I use the Victron SmartSolar MPPT 250/100 on 12V?

Yes, but it’s limited to 1,450W of nominal PV power.

What happens if PV voltage exceeds 250V?

It can damage the controller, so design strings with cold-weather margin. Above 250V, look at the MPPT RS 450.

Does the 250/100 need a GX device?

No. It works alone. A GX device adds VRM, DVCC and coordination with a CAN-bus battery.

Can I mix panel types on one controller?

Keep each string made of identical panels. Strings in parallel should have matching voltages.

Sources: Victron SmartSolar MPPT 250/70 up to 250/100 datasheet; product page, victronenergy.com, accessed Oct 2026.