BB. wrote: »
Assuming 3x panels in parallel with Imp-array~15 amps @ 36 volts and using a generic voltage drop calculator, with ~1-3% voltage drop on a 24' one way cable run:
36 volts * 3% = 1.08 volts max recommended drop
36 volts * 1% = 0.36 volts min cost effective drop
And using the calculator (trial and error) with 24' one way run:
24', 10 awg, 15 amp=> 0.9 volt drop
24', 8 awg, 15 amp=> 0.55 volt drop
24', 6 awg, 15 amp=> 0.34 volt drop
Wanderman wrote: »
I was just about to order marine 6/2 awg marine shielded cable when I remembered the slight confusion about wire runs
3 36v (nominal) panels each run separately to the Morningstar TS-45-MPPT controller. Connected directly to the lugs on the controller.
Assuming a max distance from the panels to the controller of 24 ft (likely a bit less)
What is the proper AWG to minimize loss? I believe its 6 AWG for .34 %loss....but before I order I would like to be sure as the cable is expensive!
Also will 3 6 AWG cables even FIT the lugs on the Morningstar controller??
The four large power terminals are sized for 14 - 2 AWG (2.5 - 35 mm2) wire. The terminals are rated for copper and aluminum conductors. Use UL-listed Class B 300 Volt stranded wire only.
Good system design generally requires large conductor wires for the solar and battery connections that limit voltage drop losses to 2% or less. The wire tables in the appendix on pages 51-54 provide wire sizing information for connecting the solar array and battery bank to the TriStar MPPT with a maximum of 2% voltage drop.
BB. wrote: »
Try to keep the wiring between Controller and Battery bank short... Voltage drop is not your friend (a couple 1/10's of volt drop can slow down the battery charging as the controller thinks it is almost charged).
However, you are in luck. The MorningStar TS family does include remote battery voltage sensing... You run a couple small wires from +/- battery to +/- Battery Sense on the controller--and it automagically adjusts for voltage drop in your heavy cabling (verify the MS TS MPPT family does have remote battery voltage sense--I don't have time at the moment to verify my memory).