MPPT solar charger manual

4. Installation

In this section:


The DC (PV) input is not isolated from the battery circuit. Therefore the PV, battery and control circuit are considered hazardous and should not be user accessible.


For proper temperature compensated battery charging the ambient temperature of the solar charger and the battery must be within 5°C (9°F).


The battery and PV connections must be guarded against inadvertent contact. Install the solar charger in an enclosure or install the optional WireBox.

4.1. Mounting

Mount the solar charger vertically on a non-flammable substrate, with the electrical terminals facing downwards.

If the optional MPPT WireBox is used, affix the steel WireBox base to the solar charger before the solar charger is mounted into its final position. For more information see the MPPT WireBox manual.

The Appendix of this manual contains the dimension drawing of the solar charger, this drawing also indicates the mounting holes.

Observe a minimum clearance of 10cm under and above the solar charger for optimal cooling.

Mount the solar charger close to the battery, but never directly above the battery. This to prevent damage to due to gassing of the battery.


Avoid ambient temperature differences of more than 5°C between the solar charger and the battery. These temperature differences can lead to incorrect temperature compensated charging, which can reduce the battery lifetime.

If large temperature differences or extreme ambient temperature conditions are expectedd use a direct battery temperature sense source like the Smart Battery Sense or a BMV or SmartShunt equipped with a temperature sensor.

4.2. Battery

The battery supply must be protected by a fuse as per below table.

Solar charger type

Minimum battery fuse rating

Maximum battery fuse rating

MPPT 150/70 and 250/70



MPPT 150/85A and 250/85



MPPT 150/100 and 250/100




For Canada the battery fuse must comply with the C22.2 standards.


The battery installation must be done in accordance with the local storage battery rules. For Canada this is the Canadian Electrical Code, Part I.


Use flexible multi stranded copper cable for the battery connections Also see chapter Wiring safety precautions.

4.3. PV array

The solar charger can be used with a PV configuration that satisfies both these two conditions:

  • The maximum open circuit PV voltage can not exceed 150 or 250V, depending on the solar charger model.

  • The nominal PV voltage should be at least 5V higher than the battery voltage.

The PV array can consist of mono- or poly-crystalline panels.

The solar panels are connected in series, in parallel or in series/parallel. See below figure for examples of these configurations.

Solar array configurations

Examples of series, parallel and series/parallel solar arrays.

To help calculate the size of the PV array configuration use the MPPT sizing calculator. Alternatively, use one of these PV array configurations:

PV array example 24V battery with 150V solar charger:

  • Minimum number of cells in series: 72 (2x 12V panel in series or 1x 24V panel).

  • Recommended number of cells for highest controller efficiency: 144 cells (4x 12V panel or 2x 24V panel in series).

  • Maximum: 216 cells (6x 12V or 3x 24V panel in series)

PV array example 48V battery with 150V solar charger:

  • Minimum number of cells in series: 144 (4x 12V panel or 2x 24V panel in series).

  • Maximum: 216 cells (6x 12V or 3x 24V panel in series).

PV array example 48V battery with 250V solar charger:

  • Minimum number of cells in series: 144 (4x 12V panel or 2x 24V panel in series).

  • Maximum: 360 cells (10x 12V or 5x 24 panel in series).


  • Provide a means to disconnect all current-carrying conductors of a photo-voltaic power source from all other conductors in a building or other structure.

  • Be aware that at low temperatures and depending on local conditions and cell specifications the open circuit voltage of a solar array may exceed the array's rated maximum open circuit voltage. In that case the number of cells in series must be reduced.

  • A switch, circuit breaker, or other device, either AC or DC, shall not be installed in a grounded conductor if operation of that switch, circuit breaker, or other device leaves the grounded conductor in an un-grounded state while the system remains energized.

  • Do not use solar panels with optimizers. In worst case, the use of optimizers will cause irreparable damage to the solar charger.

  • Use flexible multi stranded copper cable for the screw connections (Tr model). See chapter Wiring safety precautions.

  • For MC4 models: several of the solar charger's MC4 pairs may be needed to parallel solar panel strings. Be aware that the maximum current through a MC4 connection cannot exceed 30A.

4.4. Grounding

Battery grounding

The solar charger can be installed in a positive or in a negative grounded system.

Apply a single ground connection, preferably close to the battery, to prevent system issues or ground loops.

Chassis grounding

A separate ground path for the chassis ground is permitted because the chassis is isolated from the positive and the negative terminals.

PV array grounding

The positive and negative of the PV array should not be grounded.

Ground the frame of the PV panels to reduce the impact of lightning.

Do not connect the solar charger to a grounded PV array. Only one ground connection is allowed, and this should be near the battery.

Ground fault detection

The solar charger does not have internal ground fault protection.

The USA National Electrical Code (NEC) requires the use of an external ground fault protection device (GFPD).

The system electrical negative should be bonded through a GFPD to earth ground at one (and only one) location.


When a ground fault is indicated, battery terminals and connected circuits may be un-grounded and hazardous.

4.5. Electrical connections

Make all electrical connections in the following order:

  • Confirm correct battery polarity, then connect the battery (this will allow the solar charger to recognize the system voltage).

    Torque moment 2.4Nm.

  • Connect the remote on/off terminal (if applicable).

  • Connect the programmable relay terminal (if applicable).

  • Connect the VE.Direct communication cable (if applicable).

  • Connect the VE.Can communication cable and VE.Can terminator (if applicable).

  • Confirm correct PV polarity, then connect the solar array.

    Torque moment TR model 2.4Nm

    If accidentally connected in reverse polarity, the PV voltage will drop and the controller will heat up but will not charge the battery.

  • In case a MPPT WireBox is used:

    First: Secure all electrical cables as indicated in the WireBox installation instructions

    Then: Place the WireBox plastic cover over the solar charger connection area and secure it.

See below figure for an example of the solar charger connections:


4.6. Install the optional SmartSolar Control display

To install the optional SmartSolar Control display follow these steps:

  1. Remove the two screws of the plastic cover. Keep the screws, they are needed again when securing the display.

  2. Remove the plastic cover. The display terminal is now exposed.

  3. Remove the two plastic plugs on either side of the display plug.

  4. Remove the paper backing of the double sided tape on the back of the display.

  5. Insert the display into the plug and make sure it has been inserted all the way in.

  6. Screw the display down by using the two screws that were used for the plastic cover.

Installing a SmartSolar Control display

How and where to connect the SmartSolar Control display

For more information, see the SmartSolar Control display manualSmartSolar Control display manual


The display is hot-swappable, this means that the display can be plugged in or removed while the solar charger is operating.

4.7. Connect the MPPT Control display

Connect the (optional) MPPT Control display to the VE.Direct port of the solar charger using a VE.Direct cable.

Note that it is not possible to extend the VE.Direct cable, the maximum length can not exceed 10 meter.

For more information, see the MPPT Control display manualMPPT Control display manual


Connect the display to the solar charger via a VE.Direct cable