DIY Manual

8 | P a g e 10-543-1 REV A
DIY Manual
Which Classic is right for you? 150? 200? 250?
The Classic’s name refers to the maximum input voltage limit in terms of open-circuit voltage, or
Voc. For the Classic 150, the limit is 150V; 200V for the Classic 200, and of course, 250V for the
Classic 250.
A higher input voltage allows the system to be designed with more PV panels wired in a series
string. Remember, voltages add in series and current stays the same. The advantage of wiring
more panels in a series string is to keep the total PV current low, which allows the PV array to be
physically located a greater distance from the charge controller using smaller physical size wire.
The KID and the Brat charge controllers
The KID is a 30A MPPT controller with a 150V input limit. Perfect for RVs, boats, cabins, and small
systems. The Brat is a 30A PWM controller with a 60V input limit. Perfect for small, cost-
conscious systems. Both controllers offer advanced features such as load control and
equalization of flooded batteries. The KID has an excellent auto generator start function.
Panel wiring considerations for the KID are similar to the Classic, as mentioned above. As for the
Brat, match up nominal panels to nominal battery bank voltage. For example, with a 12V battery
bank, select a nominal 12V panel, usually about 100W with 21Voc and 17-18Vmp. The 17-18Vmp
is what the Brat will drag down to battery voltage to make power. Almost always you will wire
panels in parallel with the Brat, exception being the use of small (35W or 50W) panels.
Remember, the input voltage to the Brat needs to be slightly higher than battery voltage.
For the PWM Brat controller, select a PV module with a Vmp rating that is a few volts higher than
the highest charging voltage for your battery bank. For example, say you have a nominal 12V
bank and your battery charges to 16.2V in the EQ mode. Source a PV module with a Vmp rating
of at least 18-19V for optimal performance. You can use larger panels, such as a nominal 24V,
250W panel with a 34Vmp rating, for example. Just know - with a Vmp that high above bank
voltage the system will be less efficient as the PWM controller has to pull that higher voltage
down to the battery charging voltage. Also, wire the panels in parallel to keep Vmp the same,
otherwise you will add the voltages and the PWM controller will not be as efficient.
How many panels can a charge controller accommodate?
The MidNite Classic 150 charge controller in 12V can process up to 96A. What is the maximum
number of panels that a Classic 150 in 12V can handle?