DIY Manual

21 | P a g e 10-543-1 REV A
DIY Manual
PV Combiners
“Why You Need a Combiner”
Combining (Paralleling)
Shown on the right is the MidNite Solar MNPV3 Combiner,
configured on the left with 3 circuit breakers and a busbar;
and on the right with 2 fuseholders and a busbar. The busbar
combines (parallels) the PV strings into one common output.
The combiner offers over-current and reverse current
protection, to be discussed later, but it also offers a simple
and easy manner to combine PV strings. Additionally, since
each PV string has its own breaker, that breaker can act as an
ON/OFF switch to individually isolate one or more strings for
troubleshooting purposes.
MidNite circuit breakers and fuseholders are rated to carry 100% of the rated current. A MidNite
100A breaker can continuously carry 100A – no safety de-rating required. Be aware, breakers
manufactured by others may NOT be rated to carry the full current. A breaker can be opened
under load (that means when current is flowing through it) but a fuseholder CANNOT be opened
under load. It will be damaged! DC breakers from MidNite are designed to capture and
extinguish the DC arc caused by opening or closing a DC circuit under load. A fuseholder is not
designed to capture the arc, thus it has no where to go. Opening a fuseholder under load,
depending on the amount of current, can damage the fuse and the fuseholder.
Combining Busbars
Do NOT open a fuseholder under load!!!