PowerTech MP3741, User Manual

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Page 11
2.2 Solar Array Requirements
Serial connection (string) of Solar Panels
If you want to use more than one 12 Volt solar panel, it will be more efficient to
run them in series to produce a higher voltage. Note maximum ratings below.
If the Solar array’s power rating higher than the
MP3741’s
rated power, the
charging rate will be at the maximum a single MP3741can deliver. You cannot
add more MP3741s to utilize the extra available power from the solar panels.
You can, however, use extra MP3741’s with the same battery(s) as long as they
are fed by separate Solar Panels.
WARNING : Controller will be damaged if the Solar array maximum
open circuit voltages are exceeded. You should always measure the
open-circuit Panel voltage in bright sun before connecting anything.
2.3 Wire Size
Model MP3741
Rated Charge Current 20A
Rated Charge Power 12V: 260W
24V: 520W
Max. Solar Array Power 12V: 780W
24V: 1560W
Max. Solar open circuit voltage 92V (At 25°C)
100V (At -25°C)
Recommended minimum wire size Solar to Controller : 6mm 2 10AWG
Controller to Battery : 6mm 2 10AWG
Battery to Load : 6mm
2
10AWG
NOTE: The wire size is only for reference. If there is a long distance between the
Solar array and the controller or between the controller and the battery, larger
wires can be used to reduce the voltage drop and improve performance. The
wire size quoted above will comfortably fit the screw terminals of the MP3741;
thicker wires may require bootlace ferrules fitted. Generally, if space and budget
permit, the thicker the wire, the better.