KID Manual Firmware 1797 REV D

The Kid Solar Charge Controller Instructions
1 5 | Page
1 0-268-1 REV D
Wiring to the KID
Centered directly above the ½” conduit holes you will find the main 30 amp 6 position terminal block.
This is where you will connect PV input, loads (if any) and the battery bank. The battery bank should use
1 0AWG wire (5.26mm2). On the included wiring diagrams you will notice an external 30 amp circuit
breaker in series with the battery plus wire. This is very important and is a requirement to meet NEC
guidelines for overcurrent and disconnect devices. The battery overcurrent device regardless whether it is
a circuit breaker or fuse must be rated for the DC voltage rating of the battery bank with a minimum of
5000 Amp interrupt rating. Fuses incorporated into the KID are not to be used as these NEC required
overcurrent devices. The internal KID fuses are for internal KID operation only. MidNite Solar
manufactures numerous circuit breaker boxes for this use.
PV input overcurrent devices should follow the NEC guidelines of 1 .56 times short circuit current.
Therefore two 250 watt modules in series results in 8.87 amps of short circuit current (Isc) X 1 .56 =
1 3.83 amps. The NEC allows 1 5 amps through most 1 4AWG wire, so in this case 1 4AWG wire is
sufficient. Long distances (over 30 feet / 9 meters) may want to use larger wire to minimize voltage drop.
Now let’s take those same two solar panels and put them in parallel. This configuration will result in 1 7.7
Isc amps. Multiply this by 1 .56 = 27.6 amps. 1 0AWG wire is rated for 30 amps, so you would need to
switch to 1 0AWG wire for paralleled operation. The NEC requires a disconnect and overcurrent protection
on the PV input. Overcurrent protection can be a fuse or circuit breaker. Thermal circuit breakers require
the same 1 .56 times Isc, but MidNite solar hydraulic/magnetic breakers require only 1 .25 times Isc. All
MidNite din rail and panel mount breakers are hydraulic/magnetic and are rated to hold 1 00% current.
The use of a breaker is typical because you also get the required disconnect at the same time. MidNite
Solar manufactures Baby, Big Baby and Quad boxes to help comply with these requirements.
The wiring diagrams included in these instructions also include another breaker in series with the PV
input breaker. This additional device is a DC-GFP. (ground fault protector). The NEC mandates the use of
DC-GFP’s in all solar systems to help eliminate fires caused from faulty wiring. We find that the best use
for these devices is to find wiring errors made during the initial installation. MidNite Solar manufactures
the MNDC-GFP63 that fits in the Baby and Big Baby box along with a MNPV30 input breaker. The Big
Baby can also hold the battery breaker as discussed above. So one Big Baby box, one MNDC-GFP63,
and two MNEPV30 breakers fit the bill for all NEC required disconnects and overcurrent devices.
This marine unit should be connected to a grounded, metal, permanent wiring system; or an equipment-
grounding conductor should be run with circuit conductors and connected to equipment-grounding
terminal or lead on unit. Connections to unit should comply with all local codes and ordinances.
Connect battery positive and negative first. Then connect array positive and negative. Then apply power
by turning on the external breaker. If the polarity is correct, the unit will power up. If the unit powers up,
and the customer wants to enable the load circuit, they can then install the load fuse. The fuse does not
need to be installed for the unit to function as a charger. If the battery cables are to be removed, remove
power by turning off the external breaker and remove the fuse. Follow this procedure each time the
battery is connected/disconnected. This fuse is supplied but not installed.