Victron energy MPPT 150/70 Manual page 16

• 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.
120 W 120 W
12 V 12 V
240 W
24 V
10 A
To help calculate the size of the PV array configuration use the
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.
• Careful: when calculating the number of panels that can be used in series, make sure to take both its Open
circuit voltage (Voc) and its Temperature coefficient into account. At ambient temperatures below 25°C, the
Voc will be higher.
• 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
precautions [1].
• 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.
Page 12
MPPT solar charger manual
120 W 120 W
12 V 12 V
240 W
12 V
20 A
Examples of series, parallel and series/parallel solar arrays.
MPPT sizing
120 W 120 W 120 W
12 V 12 V 12 V
480 W
24 V
20 A
calculator. Alternatively, use one of these PV array
120 W
12 V
Wiring safety
Installation