MNPV2, 3, 4 and 6 Combiner Manual

MNPV2, MNPV3, MNPV4, MNPV6 Instructions (continued)
6 | P a g e 10- 0 1 0 - 1 R E V : G
Combiner wiring.
Caution! Always ensure that the disconnect means is turned off. Never do any wiring or cleaning/maintenance
while there is power in the combiner. Death, fire or serious injury can result.
There are numerous ways to hook up a PV array. There are no “best” or “correct” ways to accomplish this. They
all have merit. For instance if the battery bank is 24 volts and you have six 24 volt PV modules, what would be
the best way to wire them? For this installation we will assume a Classic 150 or similar charge controller that
allows the freedom to change PV array voltages.
1. This array could have all 6 panels hooked in parallel using the MNPV6 combiner and 6 MNEPV15
breakers. This array would be ok if situated close to the battery bank. It requires larger wires than would a
higher voltage array, but has the advantage of being directly connected to the battery bank in case the
controller fails. You can also substitute a PWM controller for the MPPT in the event it becomes necessary.
2. The array could be wired in three strings of two panels in series for a 48 volt nominal array. This is a very
common installation and could be made in the MNPV3. This hook up is safe from a cold VOC standpoint, but
you cannot directly connect it to the battery bank. You cannot easily hook up a PWM controller either. If the PV
array is between 30 and 100 feet from the battery bank, this hook up may offer the best power production.
3. The array could also be hooked up in two strings of three modules in series. The MNPV3 and two
breakers will accommodate this array. You have room to grow this system without adding another combiner if
only three more modules are added later. Combiners can also be combined for additional power, so if six
modules or more get added later, you can simply add an additional MNPV3. When putting three 24 V modules
in series you must pay attention to VOC during cold spells so that you do not over voltage the controller.
MidNite Solar breakers are rated for 150 and 300VDC. This configuration works very well especially when the
array is far away from the battery bank. You can sometimes save enough money on reduced wire size to pay for
an MPPT charge controller. The following wiring diagrams are intended to help you decide which type of
combiner installation to do.
Be sure to comply with all local and national code requirements including National Electrical Code, ANSI/NFPA
70. Use Class 1 wiring methods for field wiring connections to terminals of a Class 2 circuit. Use only 14-1/0
gauge AWM wire. Select the wire gauge used based on the protection provided by the circuit breakers/fuses.
Combiners should be mounted with #10 or larger stainless steel hardware.
MNPV3 With circuit breakers
MNPV3 With fuseholders
MNPV6 With circuit breakers
Always install the busbar with the box lug to
the left of the fuseholders as shown above.
This is necessary to maintain safe spacing.