Re: mixed panel question
Roughly, the maximum panel wattage your MX60 can econnomically put into the 24 volt battery bank:
Next, looking at the Outback array, what is the series/parallel combination of solar panels are you currently running?
- 60 amps * 29 volts battery charging * 0.77 system derating = 2,260 watts or so maximum
Roughly, you can connect in parallel any panel (or panel string) that is within ~10% Vmp of each other (i.e., 20 volts and 22 volts--just made up numbers to illistrate the rule). And for series connections, again Imp within ~10% of each other.
It is not to say that you cannot connection panels with specs. >>10% missmatch--but it can cause loss of array output and/or confuse the MPPT charge controller (i.e., putting Vmp=24 volt panels in parallel with Vmp=16 volt panels).
In some cases, assuming you are in a hot climate, your 15.9 volt panels, for example, may not properly equalize a 12 volt battery bank on a hot day (equalizing a 12 volt bank requires ~15 volts, and Vmp can fall on hot days below 15 volts).
For the Outback, you could put two x 15.9/17.x panels in series and just meet the nominal voltage requirement for charging your 24 volt battery bank... Or you could put 3 to around 5 or so panels in series and operate the cabling at less current, and give lots of head room for battery charging and wiring drops.
The other thing for safety, is each of these parallel connected strings should have a series protection fuse/breaker/combiner box to prevent any short in any single panel/wiring from getting fed current from the rest of the panels and possibly starting a fire.
20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.